WAIS and WMS discrepancy

[clinpsychgirl]

So, I am a newbie to the world of adult assessment. I have done my first WAIS/WMS combo assessment and have a question- and would greatly appreciate any feedback.

Hopefully this isn't beyond the scope of what's appropriate for SDN, but I was wondering how one would address in a brief report if their test subject rocked their WAIS (very superior across all indexes) and then does average across the board on the WMS (with the exception of working memory, which was above average)? What is that supposed to "mean" anyway? Thanks in advance.

 

[Logic Prevails]

I was wondering how one would address in a brief report if their test subject rocked their WAIS (very superior across all indexes) and then does average across the board on the WMS (with the exception of working memory, which was above average)? What is that supposed to "mean" anyway? Thanks in advance.

Someone else can give their take, but I probably wouldn't interpret it to "mean" anything really. Someone with above average cognitive abilities would not necessarily be expected to have above average memory. Think about what you are measuring... I would think the ceiling would be much lower for memory compared to IQ. If there were a couple standard deviations difference between the two, then I might interpret something, but otherwise, I'm inclined to say "no big deal."

Someone else might have a different opinion.

 

[clinpsychgirl]

Thanks for your feedback. I agree, especially considering that the WMS performance was average and was is only a relative weakness when compared to the WAIS scores.

Interestingly, the differences between the WMS indexes and the FSIQ score of the WAIS scores were substantial (e.g., occured in 1% of sample). So, I performed a more sensitive comparison looking at Verbal IQ and Visual Immediate Memory, and it yielded the same difference.

What complicates the interpretation is that the Working Memory Score was a relative strength on the WMS, which would technically mean that the test subject has a greater capacity to remember complex stimuli. However, if one goes by the text book (and I am unfortunately rather reliant on a textbook as a student with limited clinical experience) the findings where the FSIQ and the WMS subtest differ substantially may point to organic brain dysfunction. I guess I just feel like recommending a rule-out of "organic brain dysfunction" is a very loaded recommendation, especially when working memory was a relative strength and the WMS findings were average when compared to the standardization sample.

I think I'm going to make an executive decision here and not include a rule-out of brain dysfunction in my report.

Hehe, the things you future clinical students have to look forward to!

 

[clinpsychgirl]

it does seem silly doesnt it?

 

[Logic Prevails]

What complicates the interpretation is that the Working Memory Score was a relative strength on the WMS, which would technically mean that the test subject has a greater capacity to remember complex stimuli.

Keep in mind that the working memory index is only made up of two subtests. In my experience, when an index is "out of whack" - it is always this one. I question its validity and its reliability more than the others. If a person does extremely well relative to the other indices, it could just mean that they have good number/sequencing skills - thats it. Remember that just because a test is called "working memory" doesn't necessarily mean that it is a good measure of it.

...findings where the FSIQ and the WMS subtest differ substantially may point to organic brain dysfunction.

When you are talking about strengths (high IQ vs. "average" memory), you wouldn't want to make this inference - I think your text may be assuming differences in the other direction. Even so, I think you are right in your not jumping to conclusions - I would not infer any kind of dysfunction with the information you provided.

 

[Dr.JT]

So, I am a newbie to the world of adult assessment. I have done my first WAIS/WMS combo assessment and have a question- and would greatly appreciate any feedback.

Hopefully this isn't beyond the scope of what's appropriate for SDN, but I was wondering how one would address in a brief report if their test subject rocked their WAIS (very superior across all indexes) and then does average across the board on the WMS (with the exception of working memory, which was above average)? What is that supposed to "mean" anyway? Thanks in advance.

It is just strengths and weaknesses. Besides the WMS norms are wacky so don't read too much into "normal range" discrepancies. Personally, I never use the WMS.

 

[clinpsychgirl]

thanks all for the feedback. This was for an assessment class so please forgive my clinical naivete!

 

[Neuro-Dr]

I would not say that it is a case of don't worry about it as much as I would say that you are asking the wrong question.

Memory scale do not tap into the same areas of cortical functioning as the LTM available in the neo-cortex. You are measuring the functioning of the midline diencephalon, medial temporal lobe and basal forbrain and then asking it to be reflective of the same type of distribution as an IQ test that is much more cortically mediated.

The fact is that these are phylogenically older structures with much tighter distributions. The average WMS score (any) for an IQ of 70 is still in the low to mid 80s and for 130 is in the mid 110s. This is true for children as well using the WISC and CMS. The ditributions are much tight and that makes sense with the anatomy under consideration.

Not knowing your referal questions makes this an exercise in futility. I might be moved by this, I might not, but without know why you gave the test and what is wrong with the patient, I can't say. If I were in Vegas and betting blind, I would agree that this is likely nothing. But not for the same reasons.

 

[Logic Prevails]

I would not say that it is a case of don't worry about it as much as I would say that you are asking the wrong question.

Memory scale do not tap into the same areas of cortical functioning as the LTM available in the neo-cortex. You are measuring the functioning of the midline diencephalon, medial temporal lobe and basal forbrain and then asking it to be reflective of the same type of distribution as an IQ test that is much more cortically mediated.

The fact is that these are phylogenically older structures with much tighter distributions. The average WMS score (any) for an IQ of 70 is still in the low to mid 80s and for 130 is in the mid 110s. This is true for children as well using the WISC and CMS. The ditributions are much tight and that makes sense with the anatomy under consideration.

Not knowing your referal questions makes this an exercise in futility. I might be moved by this, I might not, but without know why you gave the test and what is wrong with the patient, I can't say. If I were in Vegas and betting blind, I would agree that this is likely nothing. But not for the same reasons.

Good post. If I were to break my thoughts down into neuroanatomy, they would certainly confer.

Just another thought: "Working Memory" is one form of memory that doesn't fit with the more temporal/diecephalic localization. If we did have good measures, they would map onto more prefrontal areas... IF we did have a good measure of working memory, you might interpret the better score on this subtest to represent the greater range of variation one might expect of prefrontal / working memory performance relative to lower-level structures. You might also expect this component of memory (if you want to call it that) to have a greater correlation to IQ. But, as I've said, the measure from the WMS is crap and I would be careful about how you interpret the working memory subtest.

 

[NeuroPsyStudent]

Interesting discussion. I work with kids and do not use the WMS, but am very familiar with the CMS and WRAML, neither of which seem to have such tight scales. In other words, I see a full range of memory capacities as measured by these tests (and obviously, variation within each profile). How would you characterize the distribution of adult memory capacities (and here I am speaking of the memory systems, not working memory)? Are the tails of the distribution very long and thin? Would not standardization correct for this? Who are the people in the tails? I do not mean to challenge, just as a student I am trying to learn...

It may also be interesting to note that recall capacity is highly impacted by EF. For example, you will remember better if you can comprehend the central coherence of something. Some people remember small units of information, while others are gestalt types. I am wondering if you saw any such patterns on your WMS.

 

[Dr.JT]

I would not say that it is a case of don't worry about it as much as I would say that you are asking the wrong question.

Memory scale do not tap into the same areas of cortical functioning as the LTM available in the neo-cortex. You are measuring the functioning of the midline diencephalon, medial temporal lobe and basal forbrain and then asking it to be reflective of the same type of distribution as an IQ test that is much more cortically mediated.

Which is exactly why such WAIS/WMS discrepancy scores are essentially useless and the data presented here, barring other info, should not raise significant concern. The only recommendation that could be added is a follow-up neuropspych eval in 1 year since this may be MCI presenting in an individual with high "cognitive reserve." That's assuming this is an individual who is of advanced age of course. Although, using a better group of neuropsych tests with better norms would shed more light on this without a follow-up. All that time administering the WMS and it gives you so little.

 

[Neuro-Dr]

I've sort of lost track as to where all of this is going. There is a pretty strong correllation between WM and VIQ (.65) and (.80) with other measures of span and D'Esposito and other s have mapped this onto dorso-lateral prefrontal cortices since the mid 90's. I'm not sure I understand what point you are making other than to say that it is moving more with cortical measures such as the WAIS instead of the other WMS scores which I guess should be obvious.

I'm also not sure about the other post regarding the CMS since it shares almost identical data to the WISC-IV in that 70 on the WISC-IV will give you mid 80's on the CMS and 130 will give you 115 or so. The technical report is available through Harcourt. It doesn't move any differently in a normal, unimpaired population than the WMS in adults.

As for the WMS in general, it is not fair to rate the goodness or badness of any test based on these types of questions. To understand the WMS is to know it's average scores in normal and impaired populations, I'm not sure you will get Cohen's d of 2.5 or higher as you would with some screening measures, but people should not get so frustrated that the average mild DAT scores are in the 70-80 range either. Is this the best test with demented patients? That depends. Other NP tests suffer similar issues, with the MAS colapsing all scores for subjects over 75. In cases where lateralization is an issues, you have more problems picking outside a standard battery such as RAVLT/RCFT that while normed together, do not reflect the same paradigm and the RCFT is so loaded on Exec Funtion in the copy portion that the memory portion can be rendered meaningless. Others are simply not normed together.

In kids the CME recognition functions as an all or nothing measure with 30/32 normal and 29/32 impaired, which implies significant floor issues.

With the RBANS, I can't tell you how many 55-60-y-o bright folks with minimal memory issues come in for evals, get WMS scores in the 110's or higher and then 80's on the RBANS becasue of these floor issues in a younger sample, which one is the problem in these cases. When mild DAT scores 80 on the WMS, 55-60 on the RBANS memory and a DRS of 120, what is that. I have no problem saying mild impairment since I understand the ceiling and floor issues with each test. The fact is that you CAN'T get impairment on the WMS Faces if you are older than 85 because you'd have to score below chance, which would imply malingering. But in a TBI sample these problems do not occur.

In large part, these are the main reasons why we teach pathology in grad school for NP and psychometrics as opposed to instruments, because there would be no reason to give the WMS in a case where memory problems are not modal deficits for the disorder under question, which we still don't know from the OP.

Those who learn only the instruments are lost on these more complex issues and then blame the tests for their misunderstanding of the findings as opposed to their limited understanding of the pathology they study.

 

[justapuppy]

Hi there guys, (are any of you still around 4 years on?)
I'm also new to administration of tests, and need some pretty thorough advice. All bits here refer to WMS-III, and WAIS-III

This is my case:
60yr old male 'high average' FSIQ, and others (aside from Processing Speed, 21%ile), very low WMS scores (percentiles from 3-9), aside from working memory - 77%ile.

My questions are :

• Any references to point me to re. reasons for administering WMS and WAIS in looking at memory issues?
• Any benefits in also administering the WTAR?
• Where would I go to to compare WAIS and WMS scores to look at discrepancies.

Thanks to anyone willing to help

 

[erg923]

Whats your refferal question?

As far as "where to go" to compare scores....I would suggest a local coffee shop.
But seriously, I'm not sure what you're asking?

 

[PsyDr]

consult with the contrast scores in the WMS manual to determine the probability of such scores.

 

[Therapist4Chnge]

The testing manual is the first place to look. Then I'd check, "A Compendium of Neuropsychological Tests" to see what they say about discrepencies between the WAIS & WMS subtests. I know they published data on it, though I'm not sure if the charts are 3rd party data or just reprints from the original WMS research. I also know Dr. David Tulsky put out multiple articles on WAIS / WMS comparison in the early 2000s, a quick search should turn up some useful articles. My guess is the probability will be very very low, and then you are left to explain the "why".