WILLIAM E. BENET, PH.D., PSY.D.
Clinical Psychologist

Psychological and Educational Assessment and Testing

Benet Clinical Assessment - Exploring the Mind Benet Clinical Assessment - Solving the Puzzle Benet Clinical Assessment - Testing and Comparing Benet Clinical Assessment - Measuring Growth Benet Clinical Assessment - Thinking and Planning
Member, American Psychological Association
Florida Psychological Association
Licensed, Florida Department of Health, Board of Psychology PY 4057


Neuropsychology FAQ
From Neuropsychology Central



Neuropsychology Q&A

Questions & answers on neuropsychological assessment with Gordon I. Herz, PhD,
from the American Psychological Association's Practice Directorate online discussion forum,
Sunday, February 10, 2002, reprinted with Dr. Herz's permission.

"No matter how good the imaging methods become to localize the lesion, they may
never tell us about HOW THE PERSON FUNCTIONS, and the correlation with real world
behavior. This is nexus at which the neuropsychologist functions."--Gordon Herz, PhD

Question:

"...I guess I still have a few doubts about how precise the neuropsychological tests are
 (other than as tests of functioning) or how useful it is to try to name the specific areas in
 the brain which are associated with different psychological functions. I mean, does it  really
 help people to tell them that the problem is in the front of  their head or the back  of their
 head or the middle of their head?"

Dr. Herz:

Great comments and question. Yes, I think it could matter.

It could have implications for the disease process, thus potentially predicting likely prognosis
and useful treatments. For a basic example, if cognitive deficits imply the 'front' part of the
brain but other cognitive functions (brain areas) are spared, this might suggest a 'frontal'
dementia, as opposed to if 'deep brain' functions are affected (i.e., motor, memory), this might
suggest a Parkinson's type dementia. [Now you are right, our testing methods might not be
this accurate yet, but this is improving all the time]. Both of these entities have different
etiologies, may have no other 'objective test' or biological markers to differentiate between
them, have different implications for the patient, family, and treatment options, etc. Unless of
course one takes the somewhat pessimistic view that in the dementias the course is inevitably
downhill anyway, so what's the difference? As suggested, sometimes the neuropsychological
testing provides a 'noninvasive' way that may add to the 'soft signs' yielded, for example, by a
neurological exam, even to the exquisitely good localization offered by an imaging technique,
to help make the diagnosis.

This is an area of the literature I'm not too familiar with, but I believe some of the batteries of
neuropsychological tests are actually more sensitive than other techniques currently available
to detect, for example, Alzheimer's in its early stages, but especially to help predict any
'subtypes' and classify with a certain probability the likely rate of progression. These could be
important to a patient and family.

Question:

"And if localization is so important (for surgery perhaps), wouldn't more direct imaging
 techniques, PET scans, etc. give better accuracy?"

Dr. Herz:

Another excellent question. I was being trained in neuropsychology about when CT was
replacing techniques such as pneumoencephalograph, contrast-dye injection-type procedures.
We always had hot debates about whether increasingly good imaging would render
neuropsychology obsolete. This was not unimportant to the neuropsychology graduate student!
I don't worry about that any more.

Clinical neuropsychology is much more about assessing FUNCTION, secondarily inferring from
that known brain locations, conditions, processes if need be, thus as a diagnostic procedure
when dx may not be known, but is much more important in relating this to rehabilitation,
restoration, compensation for lost function in real-world situations. In order to know that, you
have to know about the neuro (cognitive) (logical) conditions, and how your test results relate
to those.

An example: An EARLY Alzheimer's patient, albeit with measurable memory dysfunction and
exquisitely well-pinpointed loss of volume in the hippocampus by MRI, may nevertheless be able
to operate a motor vehicle safely with compensatory methods. No matter how good the imaging
methods become to localize the lesion, they may never tell us about HOW THE PERSON FUNCTIONS,
and the correlation with real world behavior. This is nexus at which the neuropsychologist functions.

Question:

"Of course, the tests that relate to driving functions do seem to be quite useful, but these are
just tests of functioning and don't require a "neuro" label or location do they?"

Dr. Herz:

Well, I'll agree. There may not be anything in particular about some tests that require the
'neuro-' label at the front of them.

Actually, I think about it the other way around. ALL TESTS ARE NEUROPSYCHOLOGICAL. If you
think about it, just about any 'test' (by which I mean a reproducible stimulus eliciting a
response) MUST BE a 'neuropsychological test' if it filters through the CNS. About the only
thing I can think of that wouldn't be would be a 'knee-tap' test that filters only through at the
spinal cord level. A test can even be 'neuropsychological' if, for example, the patient is
comatose or vegetative, i.e., 'evoked potentials' tests that probe the pathway of input all the
way to the cortex.

What makes a particular test 'neuropsychological' in my view is several factors. At its best, a
test is neuropsychological if it is based on a theory of human brain functioning, for example, a
model that asserts important domains of functioning include level of arousal, information
processing, and planful responding. A test might be constructed to tap one or more of these
domains.

Other features I would think are important to label a test 'neuropsychological' might have to do
with: its known relationship to brain locations/systems; its known stability or change in response
to various CNS conditions, and of course the purpose for which the test is used. The use of the
'neuro' label I think has much more to do with the construction, purpose of administering, and
the interpretation of the instrument itself than, necessarily, the test itself.

For example, think of the use of the WAIS-III as a 'neurocognitive' test. Not initially designed
for a neuropsych purpose, but when correlated with models of important cognitive domains
other than 'g' (look at the 'processing speed index,' for example) with effects in individuals with
known brain illness, etc, and when interpreted in these contexts, the USE OF the instrument
may become 'neuropsychological.'


Gordon I. Herz, PhD
Private practice in neuropsychology
Madison, Wisconsin


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