ASSIGNMENT 2 – A CASE OF DEMENTIA? ANNOTATED LECTURE NOTES

 

 

Three types of information have been presented that you must process and learn how to utilize in order to successfully complete this assignment. What follows is a written version of the material presented in lectures and the residential schools designed to achieve this goal of aiding you in mastering this material.

 

The three types of information are the introductory background material for the case, information regarding the tests that have been utilized in the assessment, and the testing results along with the standardization tables necessary to interpret them. I shall proceed in the order in which the information is presented in the assignment. As the introduction to the assignment tells us:

 

“Dr. Alvarez is a 62-year-old academic who for the past few years has been concerned about his failing memory.”

Okay, let’s start here! What have we learned so far? In addition to learning that our client is a male in his ‘60s with a high level of education, we are getting our first indication of the reason for referral – memory problems – this does not mean that he must necessarily have memory problems but rather that his perception of his difficulties are related to memory functioning.

 

 “He has had a long and distinguished career as an academic and has taught English Literature in the Faculty of Arts at the local university for the last thirty-two years.”

On the basis of this statement I would have an expectation that his verbal abilities should be at least be above average.

 

“He has found life to be considerably less enjoyable since his wife passed away just over eighteen months ago, but has found some solace in his continued love of teaching and the enjoyment he still gets from reading the great classics.”

This raises issues and concerns such as bereavement and depression, but also suggests that despite whatever grief he may experiencing, work is still rewarding for him.

 

 “Twelve years ago, Dr. Alvarez was the primary caretaker of his ailing father who died of Alzheimer’s disease. He recalls vividly that the first indication he and his wife had that anything was wrong with his father  was a persistent and worsening problem with memory. His father had been an intelligent man who, although poorly educated, had passed on his joy of reading to his son. Dr. Alvarez watched while his father, a robust vital man with a deep appreciation for life, deteriorated into a dependent, frail and confused man before his death. Dr. Alvarez now reports many of the difficulties he observed in his father and is of the opinion that he too may have Alzheimer’s disease.

It is for this reason that he has been referred for neuropsychological assessment. Dr. Alvarez was cooperative and appeared highly motivated to perform well. He found the verbal subtests of the WAIS-III particularly easy and made no pronunciation errors at all on the NART-2. You have not been provided with data from his psychosocial assessment but the results of this testing indicated clinically high levels of depression for which he is taking antidepressant medication.”

 

Ah-hah! The plot thickens. Let’s think about what may be going on here. We do not engage in speculation at this point with the intent of prejudging the case, but rather to consider alternative hypotheses and ensure that we examine each appropriately. Dr. Alvarez has been experiencing difficulties with his memory. Let’s consider some possibilities.

1.                          The first that comes to mind is that Dr. Alvarez’ abilities are unimpaired. Many individuals experience, with increasing age, changes in their life that they may misinterpret as cognitive impairment. After I have taught the same unit for more than three or four times I have a distinct feeling that my audience has already heard all the things that I have to say. I find it increasingly difficult to separate something that I have said many times before from the groups that I have said it to. I compensate behaviourally by often saying to my classes “stop me if I have already told you this” It would not be uncommon  for individuals less aware of how memory functions to mistake this for pathological forgetting and be concerned about not being able to remember to whom you said what! This, however, is a natural consequence of the increasing interference that have been laid down in the same way and in the same context. The more times I teach the material the greater confusion I will have as to exactly where and when that information was presented. Assessment of my memory should reveal no impairment with my ability to learn novel material.

2.                          The second possibility is that Dr. Alvarez has specialist knowledge regarding Alzheimer’s disease that most people do not, having been his father’s primary caretaker through his last few years. Dr. Alvarez may be accurately recognizing the similarities between his father symptoms and his own. This hypothesis essentially suggests that Dr. Alvarez has a dementing condition such as Alzheimer’s disease.

3.                          Related to the second hypothesis, is the possibility that there are little to no meaningful similarities between his father’s memory problems and his own. This can be a case of a little knowledge can be a bad thing. Dr. Alvarez may be seeing similarities that are not relevant to his condition and his fear and anxiety about ending up like his father may be causing the difficulties he is experiencing.

4.                          Another psychosocial issue we need to consider is the potential impact of depression. He lost his beloved wife only a year-and-a-half ago and suffered the witnessing of his father’s deterioration and eventual death. Depression would certainly be an understandable reaction to these events. The case history informs us that Dr. Alvarez is taking antidepressant medication supporting the presence f depressive symptomatology and raising another associated hypothesis.

5.                          The medication Dr. Alvarez is taking to treat his Depression could also be impacting upon his cognitive functioning.

6.                          The other major consideration that comes to mind is that of Age-Associated Memory Impairment. This condition was discovered primarily through longitudinal studies designed to detect early signs of Alzheimer’s disease. These studies, by the way, also established that the old idea of senility – cognitive deterioration as a normal consequence of advancing age – is not the common lot of aged mean and women. In these longitudinal studies some people were found to demonstrate over time little change in their cognitive status – normal aging. Some showed a decline in overall cognitive functioning consistent with dementing disorders such as Alzheimer’s Disease. A third group however demonstrated declines in memory functioning with increasing age but no changes in other areas of cognitive functioning. This last group seemed to show an age-related decline in memory only which has been subsequently referred to as age-associated memory impairment. It should be stressed that these individuals do not demonstrate the normal range effects of memory associated with dfferent age cohorts. Rather there is direct evidence for impairment relative to others of their age but this seems to be restricted solely to memory functioning.

 

So, why are we considering these alternatives? They make nice stories (I particularly liked the one that suggested that the examiner of this unit may be dementing!) but surely we need evidence to determine which hypothesis is most likely! EXACTLY! The above hypotheses serve little purpose if we cannot consider how we would expect them to impact upon psychological tests. Before considering that, though, we should review the last paragraph in the case introduction:

 

“Eighteen months following the first assessment, Dr. Alvarez was assessed again using the WAIS-III and WMS-III. Psychosocial testing at this time revealed a substantial reduction in depressive symptomatology. This finding was consistent with his physician’s observation of improvement in his mood and subsequent reduction in dosage of his medication.”

 

 Okay, let’s think about this. Eighteen months later Dr. Alvarez’ depressive symptomatology has reduced, interesting! But of even greater interest is that this corresponds to his physician’s observations of improved mood and REDUCTION IN DOSAGE OF HIS MEDICATION. (I’m not sure but I think this might be important later on!!).

 

 

·        Let us now consider the likely impact of the respective hypotheses in possible test performance. It is understood that at this point in your training you may feel ill-equipped to do this. We all have to start somewhere, and in this case I will be giving you lots of prompts and guides (No, no need to thank me! It comes form a deep-seated commitment on my part to  . . . erh, hmmm! But I digress!). The hypothese will be based solely around cognitive/intellectual (read WAIS-III) and memory (read WMS-III) assessments. Hypothesis 1 was that Dr. Alvarez’ abilities are unimpaired. If this is the case then we would expect that his first assessment results would fall in the normal range, be consistent with pre-morbid estimates, and that on retest there would be no change detected.

·        Hypothesis 2 was that Dr. Alvarez has a dementing condition. In terms of psychological assessment of cognitive functioning, dementia is indicated where evidence exists for a significant decline in overall cognitive/intellectual functioning with specific cognitive deficits in at least one cognitive domain, usually memory. In this case we would expect that on initial testing there would be evidence for both memory and other cognitive/intellectual impairment and that on retest these scores would indicate further decline (There is much room for variation here but for the purposes of this assignment I am maximizing the differences between each of the hypotheses). If Dr. Alvarez is experiencing the ongoing effects of a dementing disorder, then as the disease progresses so too will his abilities decline.

·        Hypothesis 3 proposes as with Hypothesis 1 that there is essentially no cognitive impairment.

·        Hypotheses 4 and 5 are related and propose that any cognitive deficits may have are a result of his depression or the medication taken to treat it. If this is the case then we would expect to see impairment on the first testing that improves on the second testing. This improvement is predicted based upon the test data indicating a reduction in depressive symptomatology and the physician’s reduction in the amount of medication Dr. Alvarez is taking. If Dr. Alvarez’ difficulties are due to his depression and/or treatment then as this condition alleviates and medication is reduced then his cognitive functioning should improve.

·        Hypothesis 6 proposes that Dr. Alvarez is experiencing age-associated memory impairment (AAMI). This condition would predict that Dr. Alvarez’ overall cognitive/intellectual functioning would be normal on both first and second testing and that only memory deficits should be indicated in his profile which would in all likelihood continue to worsen by the second testing.

 

            These hypotheses and their impact on WAIS-III and WMS-III are summarized in the table below. Again, please understand that there is tremendous variation in how these different conditions actually alter test performances. This is an idealized representation that is designed to match the data that you have been asked to analyse.

 

	First Testing		Second Testing
Hypothesis	WAIS-III	WMS-III	WAIS-III	WMS-III
1. Normal	Normal	Normal	Normal	Normal
2. Dementia	Impaired	Impaired	More Impaired	More Impaired
3. Anxiety	Normal	Normal	Normal	Normal
4&5. Depression	Impaired	Impaired	Improved	Improved
6. AAMI	Normal	Impaired	Normal	More Impaired

 

 

 

Alright, now we’re getting down to the nitty-gritty. In the data presented to you there are direct or oblique references to four tests that were administered to Dr. Alvarez. The data for only two tests have been provided but we should, nonetheless consider the implications of all four. As I have indicated in the assignment this would constitute a poor assessment if these were the only tests administered but they data presented is sufficient to enable you to test the hypotheses generated and get a taste for the marvelous detective game that psychological assessment can be.

 

The Wechsler Adult Intelligence Scale – 3^rd Edition (WAIS-III) and the Wechsler Memory Scale – 3^rd edition (WMS-III) have been administered and some of the test scores from the initial and follow-up assessments have been provided. The data from his psychosocial assessment (that you have not been provided with) was from a test called the Minnesota Multiphasic Personality Inventory-2^nd edition and includes 567 true-false questions that the respondent has to answer. The responses can be combined into more than 250 scales that can be examined for indications of psychopathology such as depression, anxiety, physical complaints, social isolation, etc. To make you learn this test would constitute cruel and unusual punishment (and this reserved for 4^th year and Master’s students). Sufficient to say, that this test revealed large numbers of depressive symptoms that is corroborated by his ongoing treatment for depression. It is important to note that eighteen months later this test indicates a substantial reduction in the number of depressive symptoms which again is corroborated by independent medical evaluation and a reduction in antidepressant medication. The second test referred to is the NART-2. Examination of this measure is not strictly necessary to complete the assignment, but this measure would be commonly employed in cases of this type. The NART-2 consists of irregular words whose pronunciation does not conform to standard rules of English pronunciation. For example, the word “drachm” would likely be pronounced as “drak-him” by those unfamiliar with the word. Those who have been exposed to it know how to pronounce it, “dram”, albeit often with a somewhat inebriated slur. Thus performance on the test is a measure of the degree to which you have been exposed to infrequent and irregular words in the English language, something which is highly correlated with the number of years of formal education one has had. Some of the original studies with this measure have indicated that, perhaps with the exception of severe impairment, declines in cognitive functioning are NOT accompanied by declines in performance on this test. Many clinicians, therefore use the measure as a way of examining word knowledge with the expectation that whatever problem you may have has had little impact upon test performance. This is a round about (but technically accurate) way of saying that it is often used as an estimate of your abilities before you began suffering from your current difficulty. An individual hypothesized to be currently experiencing a decline in cognitive functioning could be so recognized by comparing where they should be based upon their NART-2 score with where they are now! More about this later!

 

---

THE WAIS-III

 

            The WAIS-III is a cognitive/intellectual battery of tests designed to assess a variety of cognitive domains. Most notable in the battery is the omission of tests that evaluate memory beyond that of short-term recall. The battery consists of 14 subtests only 13 of which are customarily administered. The Object Assembly subtest has been included in the third edition of the battery to maintain consistency with its predecessor (the WAIS-R) and to permit the substitution of this test for a spoiled Block Design performance. In the case that you will be analyzing no data for Object Assembly has been provided.

 

            The nature of the subtests will be discussed shortly, but analysis of the WAIS-III focuses primarily around composite scores. Composite scores are combinations of subtests according to a particular theoretical framework. The two types of composites on the WAIS-III are IQ scores (which are based upon an historical framework) and Index scores (which are based upon an empirical framework). One of the things that can be somewhat confusing about the WAIS-III is that subtests are combined in ways that are similar but not identical for the two frameworks described. Let’s consider the IQ framework first.

 

            David Wechsler, the developer of the Wechsler batteries conceived of his test as measure overall cognitive/intellectual ability in the form of score, FSIQ, that included all of the subtests on the battery. This FSIQ could be divided into two sub-categories, VIQ (which encompassed those measures that were administered verbally and required verbal responses) and PIQ (which encompassed those measures that were administered visually and usually required a written, pointing, or object-manipulation response). So essentially, FSIQ represents an overall indication of performance and VIQ and PIQ are subdivisions that relate to the mode of input and output of information. This framework has been retained in the WAIS-III with IQ scores computed from the measures that have been traditionally used for this purpose.

 

            Factor analysis of the WAIS-III, however, reveals that rather than a dichotomous verbal and visual structure to the battery, four abilities or constructs are actually measured by the test. This factor structure forms the basis of the four Index scores. VCI (Verbal Comprehension) consists of those subtests that best measure verbal comprehension and expression. POI (Perceptual Organization) consists of those subtests that best measure an individual’s ability to process complex visual information and solve problems – in some ways a non-verbal reasoning measure. WMI (Working Memory) consists of those subtests that best measure attentional abilities and the degree to which an individual can efficiently perform mental operations. PSI (Processing Speed) consists of the subtests that best measure speeded visual information processing  - these measures all involve scanning of visual information and the rapid writing of responses on a page.

 

            As you are well aware, the more items that are included on a scale the higher the reliability is likely to be. Examination of the numbers of subtests that are included in each of the IQ and Index scores (in the table below) would appropriately suggest that higher internal consistency is found in composites that contain more subtests. Our approach to analyzing psychological test data is to proceed in a hierarchical fashion from the most reliable measures and work our way down to the least reliable measures. This means beginning with FSIQ, proceeding to VIQ and PIQ, then to VCI, POI, WMI, and PSI, and finally to the individual subtest level should this prove necessary.

 

---

STRUCTURE OF WAIS-III COMPOSITE SCORES

 

No. of Subtests:                                                                                    14

 

VIQ Subtests: (Number of Items)

                                                                        Information (28)

                                                                        Digit Span (15)

                                                                        Vocabulary (33)

                                    Arithmetic (20)

                                                                        Comprehension (18)

                                                                        Similarities (19)

PIQ Subtests:

                                                                        Picture Completion (25)

                                                                        Picture Arrangement (11)

                                                                        Block Design (14)

                                                                        Digit Symbol-Coding (133)

                                                                        Matrix Reasoning (26)

 

FSIQ = VIQ subtests + PIQ subtests

 

Factor Indices:

 

Verbal Comprehension

                                                                        Information (28)

                                                                        Vocabulary (33)

                                                                        Similarities (19)

 

Perceptual Organisation

                                                                        Picture Completion (25)

                                                                        Block Design (14)

                                                                        Matrix Reasoning (26)

 

Working Memory

                                                                        Digit Span (15)

                                    Arithmetic (20)

                                                                        Letter-Number Sequencing (7)

 

Processing Speed

                                                                        Digit Symbol-Coding (133)

                                                                        Symbol Search (60)

---

The following is a general description of each of the WAIS-III subtests:

 

Vocabulary

This subtest presents 33 words orally to the test-taker and requires them to supply a dictionary style definition. It is the most reliable subtest in the scale and is the best measure of g (69% of its variance). It contributes to FSIQ, VIQ, and VCI composites and is generally considered a measure of word knowledge. This measure is heavily influenced by formal education and literacy.

 

Similarities

            This subtest consists of 19 word pairs. The test-taker’s task is to indicate how the two words are similar. More points are awarded for a more abstract relationship. It contributes to FSIQ,  VIQ, and VCI composites and is generally considered to be a measure of relational word knowledge. This measure is strongly influenced by education and literacy.

 

Arithmetic

            This subtest contains 20 items requiring progressively more demanding mental arithmetic. Factor analytic studies indicate that despite the arithmetic content that this is most commonly a measure of attention or working memory. This does not mean that people with dyscalculia or specific learning disability in arithmetic will not perform poorly on this measure. The content of the subtest requires mastery of relatively simple mathematical procedures such as percentages, averages, and probability. Consequently the influence of education on this subtest is greater than for the other measures that contribute to the Working Memory Index. This measure is included in the computation of FSIQ, VIQ, and WMI composites.

 

Digit Span

            This subtest also contributes to FSIQ, VIQ and WMI composites. The Digit Span task is the prototypical immediate memory or attentional task. On Digits Forwards, test-takers are required to repeat up to eight-digit sequences back in correct order as they were presented. The Digits Backwards task requires the digit sequences to be repeated back in reverse order. It is this second task that is, perhaps, more appropriately termed working memory as mental juggling of the number sequence is required to successfully complete the task. Characteristically, individuals recall on average 2 nire digits forwards than backwards. Less than 4% of the standardization sample recalled more digits backwards than forwards.

 

Information

            This 28 item subtest measures general knowledge through a broad range of questions about science, literature, geography, and historical events. This measure is highly correlated with educational achievement. This subtest contributes to FSIQ, VIQ, and VCI.

 

 

 

Comprehension

This 18 item subtest asks questions about social knowledge and awareness of socially appropriate behaviours and responses. A critical issue with this test is that it does not ask what you would do in a particular situation but rather what should you do. Similarly it asks not why you think something is so, but what we are taught are the reasons behind issues such as taxation, or the importance of a free-press. This subtest contributes to FSIQ, and VIQ. It does not contribute to any factor indices

 

Letter-Number Sequencing

This subtest contains seven items with three trials for each item. In some ways it is similar to Digits Forwards from the Digit Span subtest. In each trial the examinee is read a series of number and letters that have been placed in a random order. The examinee is required to reorder the numbers and letters and repeat them back in the correct ascending sequence with numbers first followed by letters. This subtest contributes only to the WMI composite. It does not contribute to any IQ scores.

 

Picture Completion

This subtest consists of 25 colour drawings of objects, people, and scenes where an important elemnt is missing. The examinee is required to indicate what important element is missing from the picture. This subtest contributes to FSIQ, PIQ, and POI composites.

 

Digit Symbol-Coding

This subtest consists of a maximum of 133 items. The examinee is presented with a table containing the numbers 1 through 9 and symbols (simple line drawings) that are associated with each number. A template which contains 133 numbers (1 through 9) in a random sequence where the numbers are presented but the associated symbols have been omitted is presented to the examinee. Beginning with the first item, the examinee must fill-in as many symbols that go with each number in sequence in a two minute period. This subtest contributes to FSIQ, PIQ, and PSI composites.

 

Block Design

This subtest utilizes up to 9 blocks each with 2 red surfaces, 2 white surfaces, and 2 half red/half white surfaces. These blocks are employed by the examinee to replicate a design presented as a two-dimensional picture. Examinees manipulate the blocks and put them together in such a way so as to produce the same design with the top surfaces. The designs become progressively more complex and go from requiring 4 blocks to all 9 blocks in order to replicate the design.This subtest contributes to FSIQ, PIQ, and POI composites.

 

Picture Arrangement

This subtest consists of 11 series of line drawings that when placed in the correct order tell a story (allegedly humorous, but clients seldom laugh). The drawings are laid out in front of the examinee in an incorrect order and the examinees task is to reorder them in the correct arrangement. This subtest contributes to FSIQ, and PIQ composites. It does not contribute to any factor indices.

 

Symbol Search

This subtest was taken directly from the WISC-III and requires the examinee to look at two symbols and determine whether either symbol is present in a sequence of five symbols. There are 60 items each with two target and five test symbols. The examinee is required to verify the presence or absence of the symbols in as many items as they can in two minutes. This subtest contributes only to the PSI composite. It does not contribute to any IQ scores.

 

---

BACK TO THE CASE

 

                         When interpreting WAIS-III, WMS-III, or any psychological test data for that matter we proceed from the most reliable measures to the least reliable measures. This approach protects the clinician from being biased by an interesting, unusual, abnormal BUT unreliable finding. The most reliable measures are less prone to random variations and our decisions are more likely to be accurate if we base our interpretations on them. Now its time for me to get on to my soapbox. I will make a statement now that will seem radical but is eminently defensible through logic and basic psychometric principles. Measures of intelligence have no meaning in a clinical evaluation. This is not because the concept of intelligence does not exist (although I have seen little evidence to support it in my career) but rather that the measurement of intelligence necessarily presupposes that the individual being assessed is normal! Said another way, when you know that someone is normal then a test of intelligence may indicate that individual’s ranking relative to other normal individuals. This is not, however, the case when we use these tests in the clinical setting. Clinically, the Wecshler scales utilize tests of different cognitive abilities that are of interest to the clinician. In this context, scores such as Full Scale Intelligence Quotient FSIQ), Verbal IQ (VIQ), and Performance IQ (PIQ) cannot be construed as measuring intelligence in any way. To believe so would be to infer that a blind person is of low intelligence (VIQ = 100, PIQ = 47, FSIQ =74) (when it’s just that they can’t see any of the Performance subtests), a deaf person is of low intelligence (VIQ=48, PIQ= 100, FSIQ = 68) (when it’s just that they can’t hear the Verbal subtests), and a dead person is just profoundly intellectually impaired (VIQ = 48, PIQ = 47, FSIQ = 45). This last little gem is a consequence of the fact that despite the fact that the dead individual makes no responses to any of the questions receiving a raw score of 0 on every subtest, the scaled score associated with a raw score of 0 is 1 (surprisingly not 0). With 11 subtests constituting FSIQ, a dead person (or your favourite piece of lint if you prefer) receives a sum of scaled scores of 11 which corresponds to a FSIQ of 45.

 

                         So, having convinced you of the evils of the pragmatics of intelligence theory, what do FSIQ, VIQ, and PIQ mean? Good question. In the context of clinical assessment FSIQ represents overall performance on the majority of subtests. It functions essentially as a grand mean. It is of value to us because it has the highest reliability and has the potential for representing overall performance on the test. However, just as a grand mean may not actually be representative, we look to subgrouping of tests to determine whether the FSIQ is representative or not. VIQ and PIQ divide the subtests into two groupings based upon their input and output modalities. VIQ subtests are all administered verbally by the tester and answered verbally by the test-taker. PIQ subtests are all administered using visual stimuli and the test-taker can respond by pointing, writing, or manipulating objects. Two PIQ subtests may also involve giving verbal responses (Picture Completion and Picture Arrangement) but the scoring of each of these tests does not rely on a verbal response. These subgroupings are historical rather than empirical. By this I mean that the existence of VIQ and PIQ as scores was based upon David Wechsler’s belief that these divisions would be meaningful and not based upon research findings that support this distinction. Empirical studies (factor analyses) of the WAIS-III in fact support four composites or indices and these form the true basis of interpreting the WAIS-III in the clinical setting. What is lucky for us is that the four constructs, in principle, reflect a subgrouping of each of VIQ and PIQ into two smaller divisions. I say, in principle, because in each case one of the subtests omitted from the IQ score is included in an index score (Letter Number Sequencing is omitted from VIQ but is part of WMI, and Symbol Search is omitted from PIQ but is part of PSI).

 

                         So in proceeding from the most reliable to the least reliable measures we begin with FSIQ, proceed to VIQ and PIQ, and then to the Index scores VCI, POI, WMI, and PSI. After, and only after, that you can proceed to consider individual subtests if they address relevant hypotheses or in order to examine the integrity of index scores.

 

            Enough chatting, let’s begin looking at the table below. The primary purpose here is to teach you how to read the information in the tables. Consistent with the approach described above let’s start with FSIQ. Dr. Alvarez obtained a FSIQ Standard Score (SS) of 138. The next column, headed %ile, indicates the relative ranking of this score in the standardization sample. Standard scores have a mean of 100 and a standard deviation of 15, so this score is about two and a half standard deviations above the mean which corresponds to the 99^th percentile. How would we say this in English? Standard scores are all age-adjusted so we could describe this as “Dr. Alvarez’s overall level of cognitive functioning is estimated to fall within the very superior range and is as good as or better than 99 percent of people of his age.” Where did I get the “very superior” statement from? The table titled “WAIS-III QUALITATIVE DESCRIPTIONS FOR IQ SCORE RANGES” in your handout.

 

The next two columns contain information regarding the 90% confidence interval at the time of testing. There are two numbers the low end of the range (Lo) and the high end of the range (Hi). These numbers tell us the range in which we can be 90 percent sure that this person’s true ability lies. Remember that the score you compute on a psychological test is just an observation. We need to determine the range in which the underlying ability we are trying to measure is likely to truly fall. This is never one score but a range of scores. So while Dr. Alvarez obtained a FSIQ of 138, these two columns tell me that I can be 90% sure that the score of 138 reflects an ability somewhere between 134 and 141.

 

                The last two columns contain the 90% confidence interval for a score on that measure at retest. The Lo and Hi columns indicate the lower and upper limits of the range. So we can be 90% sure that because Dr. Alvarez got a FSIQ of 138 at his initial testing that upon retest it will fall somewhere between 132 and 142. The implication of this is that if we tested Dr. Alvarez some time later and he got a FSIQ of less than 132 or more than 142 we would have direct evidence that his score has changed (declined if less than 132, or improved if greater than 142). As you can see these last two columns would only be used if a second testing had been performed – more on this later!

 

 

So, with the information above we can describe Dr. Alvarez’ performances on the three IQ measures and four index scores of the WAIS-III indicated in the table above. Remember that only other psychologists are going to know all this jargon, so rather than referring to VCI you would talk about a measure of his verbal comprehensive and expressive abilities. Rather than WMI you would say something like a measure of attention, concentration, and the ability to efficiently perform mental operations.

 

Now the next topic relates to the detection of abnormality in the profile of scores and uses the two tables below. We have already discussed the idea of FSIQ reflecting Dr. Alvarez’ overall level of functioning. To test this idea we need to consider that FSIQ may not be made up of 11 homogeneous test scores but rather systematic differences that average out to the FSIQ score. The first way of addressing this is to examine the subsets of FSIQ, VIQ and PIQ. If VIQ and PIQ differ significantly, then FSIQ does not represent a homogeneous level of functioning. VIQ for Dr. Alavarez is 144, and PIQ is 121. The difference between these two measures is (144 – 121 = ) 23. If we consult the table of significant differences between WAIS-III composite scores for Dr. Alvarez’ age group we find that a 7.90 difference would be significant at p=.05. The 23 point difference is much larger than this so we can confidently assert that VIQ and PIQ differ significantly.

 

Differences Between IQ Scores and Between Index Scores Required for Statistical Significance at the .05 Level of Significance for the 55 to 64 Age Group

 

But what does this mean? A test of significance is testing the likelihood that the two scores came from the same distribution. Do not be swayed by the apparent size of the difference. Just looking at the significance table for the different WAIS-III composites shows differing values form 7.90 to 11.93. These values are different because of the differences in reliability of the measures involved. The more reliable two measures are, and the more intercorrelated theyare, then the less a difference needed for significance. Just remember that good reliability results in things being more easily detected and poor reliability results in things being much harder to detect. Back to our original question here, what does it mean that VIQ and PIQ are significantly different? The easiest way to understand this is to turn it around. What is the null hypothesis? That VIQ and PIQ are identical (no difference between them). A significant difference means we reject the null and infer that the two numbers are not the same. Nothing more, nothing less. Knowing that VIQ is significantly different from PIQ and knowing that VIQ is larger than PIQ means that we can infer that Dr, Alvarez has better verbal abilities than visual/graphomotor abilities (remember VIQ and PIQ reflect the modalities of the tests).

 

Disappointed? Hoping for more? What you really probably wanted to know was whether or not the difference is clinically meaningful! This is not addressed by significance (although this is not always true) but rather by abnormality. We address abnormality by doing a “head-count”. This is the testing equivalent of asking “OK! Hands up all those people who did …”. How common is a 23 point difference between VIQ and PIQ in a person who has a FSIQ in the very superior range.  That question can be answered by the table below – 4% of the standardization sample.

 

Frequencies of Differences Between WAIS-III IQ and Index Scores for Individuals with FSIQ > 120

 

 

This raises the next big question – how rare is rare? All clinicians who use psychological tests have to ultimately make a decision about this. I can tell you what I do and why. Other decisions are not wrong but like anything else in life there are consequences to what we decide. For tests of significance I use p<.05 as the standard for a statistically significant difference with a two-tailed test. For abnormality, I consider that anything that occurs with a frequency of 1 in 20 or less (5%) is sufficiently rare to call the behaviour abnormal. I will confess, however that analyses that have a frequency of 6-10% are of particular interest to me. I am not permitted to change my criterion when I have a behaviour that occurs with a frequency between 6 to 10%, but what I can do is keep it in the back of my mind and pay particular attention to any opportunities that may arise to test the hypothesis (i.e. is it abnormal or normal). One other comment here, abnormality refers only to infrequency or rarity of the behaviour, it does not tell you whether or not the behaviour is impaired. For example, an accountant is likely to be highly skilled at mental arithmetic so his score on the WAIS-III Arithmetic subtest is likely to be abnormally higher than other scores. This abnormality will be detected during data analysis, but does not signal impairment. Some abnormalities are good – we call them skills, some abnormalities are bad- we call them deficits. You will need to determine when an abnormality is signaling a skill versus an impairment. The final criterion is the confidence interval applied to test scores. I use 90% confidence because I am happy to have an error rate of 5% at either end of the distribution. Too lax a criterion (68%) will result in too narrow a band of scores while too strict a criterion (99%) will result in a band that is too wide to be of use (i.e. I can be 100% sure that the score you got on the test was one of the scores that you can get on the test! Well, duh!).

 

            So we have a significant and abnormal difference between VIQ and PIQ. VIQ is better than the 99^th %ile and PIQ is at the 92^nd %ile. Does this look like impairment? We would not really be surprised that an English professor would have abnormally high verbal abilities.

 

            We now repeat this process for the Index scores of the WAIS-III. Six comparisons can be made: VCI with POI, VCI with WMI, VCI with PSI, POI with WMI, POI with PSI, and WMI with PSI. Essentially we are looking for significant differences to indicate where performance levels differ and then for those statistically significant differences we then examine the frequency of the difference in order to detect abnormal differences. Note that all but one of the comparisons (POI with WMI) are statistically significant, again indicating that this individual has distinctly different performance levels for each of the cognitive domains assessed on the WAIS-III: verbal comprehension, visual organization, attention/concentration, and speed of information processing. Notice also that only comparisons with VCI are associated with frequencies of less than 5% in the standardization sample. This is revealing a consistent pattern – the only thing abnormal about Dr. Alvarez’s cognitive performances on the WAIS-III relate to his extraordinarily high verbal abilities consistent with his occupation.

 

            The next table, below, can be used to examine the individual subtests for relative strengths and weaknesses. The reasoning behind this analysis goes as follows. A relative strength is a performance on a subtest that is comparatively higher than other subtests. Similarly a relative weakness can be seen on those measures that are comparatively lower relative to other measures. Each subtests is usually compared to the mean of subtests. The question is how do we compute the mean? This goes back to the discussion regarding the representativeness of FSIQ. Simply put, if there is no difference between VIQ and PIQ then the average of all the subtests administered can be used. If there is a difference between VIQ and PIQ (as there is in this case) then separate means must be computed for verbal and performance subtests.

 

Differences Between Single Subtest Scaled Scores and Mean Scaled Score at the .05 Level of Statistical Significance and Magnitude of Difference Found in 5% of the Standardisation Sample

 

	Verbal	Subtests	Performance	Subtests	All	Subtests
Subtest	p<.05	5%	p<.05	5%	p<.05	5%
VO	2.10	3.00			2.30	3.38
SI	2.77	3.29			3.12	3.69
AR	2.63	3.57			2.95	3.85
DS	2.40	4.43			2.67	4.62
IN	2.34	3.29			2.59	3.69
CO	2.96	3.57			3.35	3.58
LNS	3.16	4.29			3.60	4.38
PC			3.16	3.86	3.46	4.31
CD			3.04	4.29	3.31	4.46
BD			2.94	3.71	3.19	3.92
MR			2.60	3.71	2.75	3.85
PA			3.75	4.14	4.19	4.46
SS			3.54	3.86	3.93	4.23

 

The mean for the seven verbal subtests is 15.7. The mean for the six performance subtests is 12.7. We now compare each subtest. Subtracting the verbal mean from each of the subtests and the performance mean from each of the performance subtests indicates the yields a pattern of positive and negative difference scores. A positive value means that the subtest is above that individual’s mean score, while a negative value indicates a lower performance. Comparison of these differences with those in the table above indicate which are significantly different from their respective means. Note that the two rightmost columns are not used in this case because VIQ and PIQ differ significantly. The first thing you are looking for is whether or not each number differs significantly from it’s mean, indicated by an absolute difference greater than or equal to the cut-scores indicated in the table (we are only using columns 2 and 4 here to detect significant differences). For those measures thatare significantly different from their respective means, those that are positive are “relative strengths (S)” and those that are negative are “relative weaknesses (W)”. These findings can be used to describe where Dr. Alvarez’ strengths and weaknesses lie in terms of the behaviours assessed by each subtest.

 

Verbal Subtests	SS	SS-Mn	S/W	Performance Subtests	SS	SS-Mn	S/W
Vocabulary	18	2.3	S	Picture Completion	14	.3
Similarities	18	2.3		Digit Symbol-Coding	9	-3.7	W
Arithmetic	15	-0.7		Block Design	12	-0.7
Digit Span	12	-3.7	W	Matrix Reasoning	15	2.3
Information	18	2.3		Picture Arrangement	15	2.3
Comprehension	17	1.3		Symbol Search	11	-1.7
Lett.-Num. Seq.	12	-3.7	W
Mean	15.7			Mean	12.7

 

            A note about the subtest scores. The table below reproduces the subtests scores provided fro Dr. Alvarez. Each subtest is named and two numbers are provided. In the first column of numbers the acronym SS in this case stands for Scaled Score. Scaled scores have a mean of 10 and a standard deviation of 3 and are adjusted for the age of the information (usually termed age scaled scores). The second column of numbers indicates the percentile rank of the scaled score. For example, Dr. Alvarez’ score on the Vocabulary subtest was 18 which indicates that his knowledge of the meaning of words is as good as or better than 99% of people of his age.

 

                        

            The next table adds a little to the confusion and is strictly not necessary in the current evaluation. One of the hypotheses in this case is that Dr. Alvarez could be experiencing difficulties associated with a dementing disorder. Since such a condition requires the demonstration of a decline in cognitive/intellectual functioning this would be technically possible only in the situation where you have tested the person twice (in order to show a decline). Nonetheless, clinicians will want to evaluate this hypothesis as best they can on the first assessment. Even though a second testing has not been conducted yet, the clinician still needs two numbers to examine for a change in level of functioning. A second testing would provide the second value. On the first testing, clinicians attempt to “back-generate” a hypothetical earlier value which representes where the person would be if they had no disorder or condition. This is called estimating premorbid levels of functioning. Think of it this way: I have tested the client and need a value from his past that will accurately tell me what he was like before his difficulties. There are two primary ways of getting such values. The first is to use information that is not related to the pathology such as demographic characteristics of the individual. Such an approach asks the question “What should your FSIQ be given that you are a male in your 60’s with doctoral level education and employment as an academic. The first set of figures in the table below addresses this issue. For example, based upon Dr. Alvarez’ demographic characteristics we would estimate that his FSIQ should be 120 – actually we are 90% sure that the score will be somewhere between 102 and 138. Dr. Alvarez actually got a FSIQ of 138 which is within this expected range. Consequently there is littleevidence to suggest that Dr. Alvarez’ FSIQ has gone down from where we would expect it to have been.

 

                         The second set of figures are derived from the test that was discussed earlier and represents the other main approach to estimating premorbid abilities. In this approach we use a test that we believe is unlikely to be affected by whatever is wrong with Dr. Alvarez. Although this is a current measure we are using it to “guesstimate” what he would have looked like before his difficulties. This approach is much more restricted in terms of what you can actually predict. Since the NART is a word pronunciation test it makes sense that we can only estimate verbal abilities. So, Dr. Alvarez’ score on the NART-2 estimates his premorbid VIQ to be 122 (90% sure that it falls somewhere between 108 and 136). Interestingly Dr. Alvarez’ actual VIQ is 144 which is outside that 90% confidence band. Remember that a current score LOWER than the 90% confidence interval would signal decline or deterioration. This is not the case here. Dr. Alvarez’ verbal abilities are higher than we would expect for most people of his age which merely indicates the skill in verbal ability that we have already detected (although it does supply confirmatory evidence from another source of information).

 

 

Okay, before we go on to the memory testing let’s take stock.  Ask yourself the following questions (and answer them!):

·        What range of cognitive/intellectual functioning best represent Dr. Alvarez current abilities on the WAIS-III?

·        Does this level suggest impairment?

·        Were there any abnormalities detected in the WAIS-III scores?

·        What cognitive domains were these abnormalities related to?

·        Do these abnormalities reflect skills or impairments?

·        Is there evidence at this point for deterioration in Dr. Alvarez’ cognitive/intellectual functioning from an estimated premorbid state?

 

---

STRUCTURE OF THE WMS-III

 

            The third edition of the Wechsler Memory Scale contains a number of subtests designed to assess both short-term and long-term memory functioning. The nomenclature of measures on this test can be confusing and mixes term from classical and modern memory theory. Unlike the WAIS-III there is no one overall measure comparable to FSIQ although there are measures similar to VIQ and PIQ. In this description of the test I will only focus on those measures necessary to generate the respective Index scores and will not include the optional subtests.

 

            The WMS-III essentially measures three abilities: the ability to recall information shortly after its presentation (Immediate Memory), the ability to recall this same information after a 20 to 30 minute delay (General Memory), and the ability to attend and concentrate (Working Memory). Within each of the first two measures (Immediate and General Memory) there are subdivisions that are based upon whether or not the test is verbally or visually administered and whether or not the examinee had to recall or only recognize the information that was presented. In the case of this assignment these subdivisions are not relevant to either the analysis or interpretation. They will be discussed here for the sake of thoroughness.

The Immediate Memory Index consists of two verbal subtests (comprising Auditory Immnediate) and two visual subtests (comprising Visual Immediate). The first verbal subtest, Logical Memory, involves the presentation of two stories which are then to be repeated back by the examinee in as great detail as possible. The second story is presented a second time and recall is tested to get a gross measure of learning. The second verbal subtest, Verbal Paired Associates, presents 8 pairs of words which are read aloud to the examinee. Each word pair is an uncommon pairing of words (such as flower-paperclip) and recall is tested by the examiner supplying the first word of the pair (flower) and the examinee must supply the second word of the pair (paperclip). Four trials are administered with the examiner rereading the list of word pairs each time and testing cued recall.

 

            The two visual subtests are Faces and Family Pictures. In Faces, the examinee views 24 photographs of faces and is then asked to determine which 24 out of a further 48 faces they have seen before. The Family Pictures subtest introduces the examinee to seven characters (Grandmother, grandfather, father, mother, son, daughter, and dog – I know, I know, blatant discrimination against cat people!). The examinee is then shown four scenes in which different family members are doing differenmt in things in different parts of the picture. After seeing all four scenes, the examinee is required to indicate who was in each picture, where were they, and what they were doing.

 

            The General Memory Index consists of the delayed recall trials (administered approximately 20 to 30 minutes after the immediate recall) of these same subtests. Auditory Delayed consists of delayed recall of the Logical Memory stories and the Verbal Paired Associates. Visual Delayed consists of the delayed trials of the Faces and Family Pictures tests. A third measure Auditory Recognition Delayed consists of the recognition trials of Logical Memory and Verbal Paired Associates that are presented after their delayed recall. General Memory Index is therefore made up of Auditory Delayed, Visual Delayed, and Auditory Recognition Delayed measures.

 

            The Working Memory Index consists of the Letter-Number Sequencing subtest of the WAIS-III and a visual span task called Spatial Span. This task is very much like digit span except that rather than repeating forwards or backwards number sequences read by the examiner, the examinee taps out (forwards or backwards) a series of patterns tapped out by the examiner on a board with ten blocks in various positions. One thing to note is that the Letter-Number Sequencing score used in this Working Memory Index is not from a second administration of the test but rather is exactly the same number as was used in the WAIS-III. I know it seems insane, the reasons are too complicated to discuss here – sufficient to say that the WMI on the WAIS-III and the WMI on the WMS-III are far from independent assessments of the same construct.

 

---

 

BACK TO THE CASE

 

Let’s now look at Dr. Alvarez’ scores on memory testing. I am going to make this section a little easier for you by reducing the amount of information that you have to process. Remembering our interpretative principle of examing the most reliable information first, our analysis will be focused on the Immediate Memory, General Memory, and Working Memory indices. All of the other indices listed in the assignment are subsets of the first two indices that relate to visually and verbally administered tests. As none of the analyses reveal anything of interest regarding the verbal versus visual presentation I will remove them from the data presented below. All of the analyses that we will be conducting here can be applied to the measures I am removing and you are more than welcome to perform them – I am only removing them because they have no impact on this particular case (which I know because I analysed the data, heh heh!).

 

            Dr. Alvarez’ scores on the WMS-III were 98 for the immediate recall of information, 81 for the recall of information after a 20 to 30 minute time delay, and 115 for his ability to attend and concentrate. These performances were as good as or better than 45%, 10%, and 84% of people of his age and corresponded to performances in the average, low average, and high average ranges respectively.

 

 

Wechsler Memory Scale-Third Edition

 

 

There are three comparisons that can be made here, the most important of which is the IM comparison with GM. This addresses the issue of whether or not Dr. Alvarez’ memory performances are detrimentally affected by increasing the delay between presentation and recall. There is a 17 point difference between Dr. Alvarez immediate IM) and delayed (GM) recall. This difference is significant (critical value of 12.8) and abnormal (estimated to occur in approximately 1% of the standardization sample). This indicates that Dr. Alvarez’ ability to recall information after a time delay is abnormally poor relative to his ability to recall information when it is first presented. The comparisons of IM and GM with Working Memory (WM) also indicate significant differences but only an abnormal difference for delayed recall (GM). Note that the difference between IM and WM, while significant is found in almost 1 in every four people (15%). This indicates that while Dr. Alvarez’ immediate recall may not be unusual for a man of his attentional abilities, his delayed recall is not.

 

 

Differences Between WMS-III Primary Index Scores for Statistical Significance at the .05 Level of Significance for the 55 to 64 Age Group

 

Frequencies of Differences Between WMS-III Primary Index Scores

 

While these findings strongly indicate impairment in delayed recall (GM) there is another method that we can use to determine whether or not his immediate memory is appropriate. Consider that this man is a university professor – one might expect that having a god memory would be something that would be needed in being an effective scholar and teacher. We address this issue by asking whether or not Dr. Alvarez’ WMS-III scores are normal for a man with his intellectual abilities (as indicated by his FSIQ). The table below (again altered to remove the unnecessary comparisons) addresses this question. Based upon Dr. Alvarez’ FSIQ score we would expect that his predicted IM and GM scores would be 122 and 123 respectively. He actually obtained 98 and 81 for these measures yielding differences of 24 and 42 points between estimated and obtained scores respectively. Both of these differences are significant and abnormal. This indicates that Dr. Alvarez’ scores on memory testing are abnormally low for a man of his cognitive/intellectual abilities.

 

 

Comparisons of WAIS-III and WMS-III Composites Using Predicted Difference Method (Based Upon a FSIQ of 138)

 

 

Let’s consider those questions again with respect to the WMS-III:

·        What range of memory functioning best represents Dr. Alvarez current abilities on the WMS-III?

·        Does this level suggest impairment?

·        Were there any abnormalities detected in the WMS-III scores?

·        What abiltiies were these abnormalities related to?

·        Do these abnormalities reflect skills or impairments?

·        Is there evidence at this point for deterioration in Dr. Alvarez’ memory functioning relative to his other cognitive/intellectual functioning indicated on the WAIS-III?

 

 

Hang in there! Almost done!

 

We can now look at the testing from eighteen months later. This analysis is the most straightforward but it requires you to work with information from multiple table. Again for simplicity’s sake I will remove the irrelevant WMS-III measures.

 

            Now this is where those retest confidence intervals from the first testing come into the analysis. The retest confidence interval allows us to determine whether or not scores on the second testing have deteriorated, stayed the same, or improved. You will remember that this determination is critical to our differentiating among the alternative hypotheses.

 

Results of Psychological Testing Eighteen Months Later

 

 

We will now generate a table that combines the information from our first testing and second testing. We need the 90% RETEST confidence bands from the FIRST testing, the actual scores from the  SECOND testing and then consideration of where these scores fall relative to the retest bands. Scores that fall within the retest band are unchanged. Those below it, have declined, those above it have improved.

 

 

This analysis indicates that only immediate memory and delayed recall (General Memory) measures have declined, all other measures have remained unchanged. Remember I said earlier that I keep in mind those differences that are not infrequent enough to be abnormal (<5%) but close enough to worry about (<10%). This was the case with Dr. Alvarez’ processing speed index from the WAIS-III. The question I was asking myself was whether this was a normal score for this man, or perhaps an abnormal score that isn’t quite bad enough YET for me to detect it. Examination of this score on retest resolves my concerns. PSI was clearly normal range variation as it has remained unchanged on the second testing. If it too had declined then this would suggest impairment in another cognitive domain.

 

All that is really left now is to go back to look at how we expected the different hypotheses to manifest on psychological testing. This will help is determine what is the most likely explanation. I will not do this for you (I have to leave some fun for you!).

 

This is a demanding assignment because it asks you to grasp a lot of information to which you have not been formerly exposed. However, this is a good model of exactly how 21^st century assessors go about analysing and interpreting psychological test data. Before you feel too hard done by, consider the small number of variables that you have to consider in this case from only two tests. In a routine assessment in my own clinical practice more than twenty tests are customarily administered each with many scales and subscales. The process you have learned here is identical to that used to analyse twenty tests or two hundred variables – it is just more complicated. The other warning I should give is that this case has been structured and oversimplified. It is not always the situation that cases as straightforward as this one do not occur, but they are few and far between. Most cases requiring psychological assessment are highly complex and full closure is seldom achieved. The process is the same as in this case, but the outcome is rarely as neat.

 

This concludes the ancillary materials provided to assist you in completing assignment 2. Enjoy!

 

Dr. Graeme Senior

Senior Lecturer

Department of Psychology

University of Southern Queensland