We conducted full diagnostic evaluations, including a comprehensive cognitive assessment battery, of a group of 32 elderly subjects with a clinically identified mild cognitive impairment and a group of 32 age-matched and education-matched normal subjects. The mildly impaired subjects performed significantly more poorly than the controls on tests of recent memory, remote memory, language function, concept formation, and visuospatial praxis. Follow-up evaluations of cognitive status 2 years later revealed clinically detectable cognitive decline relative baseline in 23 (72%) of the mildly impaired subjects. Several of the objective psychological tests accurately discriminated at baseline between the decliners and nondecliners in the mildly impaired group. Among the 20 mildly impaired subjects with no complicating conditions, 16 exhibited cognitive deterioration between baseline and follow-up. These results suggest that most elderly subjects with mild cognitive deficits, as determined by clinical evaluation and objective psychological testing, will manifest the progressive mental deterioration characteristic of dementia and that psychometric predictors can be used to distinguish between benign and more significant underlying disorders in mildly impaired elderly subjects.
Elderly individuals with subjective perceptions of cognitive decrements who fail to provide clear evidence of cognitive impairment upon clinical interview are not at high risk for progressive cognitive deterioration over the subsequent 3- to 4-year interval.
Scopolamine hydrobromide, 0.43 mg/70 kg, was administered by subcutaneous injection to ten young and ten elderly subjects. A comprehensive neuropsychological test battery was used to assess the effects of scopolamine, as compared to placebo, on cognitive function. As previously reported for this group of young subjects, scopolamine significantly impaired performance on tests of recent memory and visuospatial praxis. The same effects were observed in the elderly subjects, but the magnitude of the effects was much larger. The scopolamine injections produced significant psychomotor slowing in the elderly, whereas higher doses of the drug are required to produce this effect in young subjects. In both young and old subjects scopolamine failed to affect immediate memory, language function, object sorting, and the frequency of intrusion errors (although trends toward an effect were more apparent in the elderly). Remote memory, tested in the elderly only, was also unaffected. The results suggest that scopolamine's cognitive effects are quantitatively more pronounced in elderly subjects than young subjects, but that they are qualitatively similar and do not constitute a valid model for the cognitive dysfunction associated with Alzheimer's disease.
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