Page 138 - The Memory Program How to Prevent Memory Loss and Enhance Memory Power

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Neuropsychological (Cognitive) Testing

Neuropsychological testing typically reveals that loss of recent memory is the only deficit in the
disease's earliest clinical stages, which progresses over time to widespread memory loss, great
difficulty in naming objects, poor fluency in reciting verbal material, and defects in constructional
(drawing a cube, for example) and visuospatial abilities (finding the way to the neighborhood store).
However, age and education strongly influence test scores, and these patterns of deficits can occur in
conditions other than Alzheimer's disease. (Mary O'Brien, the steady alcohol user, was wrongly
diagnosed with Alzheimer's disease based on neuropsychological testing.) The great strength of
neuropsychological testing is its ability to pick up subtle, very early memory deficits.

Difficulty Identifying Smells

It sounds a bit strange: difficulty in identifying smells occurs early in the course of Alzheimer's
disease. But there is a sound physiologic explanation: neurofibrillary tangles, a neuropathologic
hallmark of Alzheimer's disease, infiltrate the “olfactory” or smell tract of nerve cells that goes from
above the nose to a brain region just below the hippocampus. There are reliable standard tests of
smell or olfaction that involve scratching a card and identifying the smell using a multiple-choice
format. Our research group recently showed that the inability in people with mild memory loss to
accurately identify smells strongly predicts who will later be diagnosed with Alzheimer's disease.
Although the findings were strong, a number of factors can distort he results of the smell test: natural
smelling ability varies markedly among people, smell discrimination skills diminish gradually with
age, and smoking worsens smelling ability. So this test can provide a guideline but is by no means
foolproof.

Brain Imaging in Early Diagnosis

In an earlier chapter, I discussed how an MRI scan can detect reduced size of the hippocampus and
how SPECT and PET can detect reduced blood flow or metabolism in the parietal and temporal
lobes. These features distinguish Alzheimer's patients from normal elderly people, but may not be as
good in predicting who will get Alzheimer's in a group of people with mild memory loss. There are a
few situations where these imaging procedures may be helpful— for example, a fifty-