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Three cases of slowly progressive speech and language disturbance were studied at various points post onset (three, five and 15 years respectively). Language, neuropsychological and brain imaging (computer tomography and positron emission tomography) evaluations were completed on all three patients. The data suggest that the syndrome of "progressive aphasia": 1) does not involve a uniform symptom complex; 2) does not necessarily develop into a full blown dementia syndrome; 3) varies greatly in rate of progression from case to case; 4) is associated with normal brain structure (on computer tomography); and 5) is associated with abnormal left temporal lobe metabolism as measured by fluorodeoxyglucose (FDG) positron emission tomography (PET). One patient had histological findings consistent with Alzheimer's disease at necropsy.

The P300 (P3) wave of the auditory brain event-related potential was investigated in patients with probable Alzheimer's disease to determine whether P300 latency discriminated these patients from controls and whether prolonged P300 latency correlated with rates of brain glucose metabolism as measured by Positron Emission Tomography. P300 latency was prolonged by more than 1.5 standard deviations from age expectancy in 14 of 18 patients, but none of 17 controls. In these subjects P300 latency was shown to be inversely correlated with relative metabolic rates of parietal and, to a lesser extent, temporal and frontal association areas, but not with subcortical areas.

Diagnosis of Alzheimer's disease (AD) during life relies upon clinical and neurobehavioral symptoms but is presumptive without microscopic verification of neuropathology. Studies in this review observed considerable heterogeneity in AD symptoms and did not agree on how to detect the earliest symptoms. Problems exist in diagnosis. Differences in symptoms and diagnosis result from how AD is defined neurobehaviorally and on the model used for description. The studies reviewed have been considered under three basic models: A severity (staging) model; a heterogeneity (subtyping) model; and an information processing model. Differences in model intent have resulted in differences in disease description. Brain imaging measures have not invalidated models but add the neural substrate needed to examine correlation of measures within each model.

Patterns of local cerebral glucose utilization were determined in moderately to severely disabled patients with D (N = 7), MID (N = 6), and AD (N = 6), and in normal controls (N = 6), using positron emission tomography with the 18F-fluorodeoxyglucose method. Average global metabolic rate was decreased 30% in patients with AD, but overlap among the other groups reduced the discriminant value of this measure. In depressed patients, the cerebral metabolic pattern was normal, except for evidence of hypometabolic zone in the posterior-inferior frontal cortex which was of marginal statistical significance. In MID, focal metabolic defects were scattered throughout the brain and exceeded the extent of infarction. In AD, metabolism was markedly reduced in cortex, especially parietal cortex, but relatively preserved in caudate, thalamus, anterior cingulate gyrus, pre- and post-central gyrus, and calcarine occipital cortex, a pattern duplicating the degree and location of pathological and neurochemical alterations characteristic of this disorder.

No previous study of Alzheimer's disease has, to our knowledge, assessed the effect of both age at dementia onset and gender on cerebral glucose metabolic patterns. To this end, we used positron emission tomography (fludeoxyglucose F 18 method) to study 24 patients with clinical diagnoses of probable Alzheimer's disease. Comparisons of the 13 patients with early-onset dementia (less than 65 years of age) with the 11 patients with late-onset dementia (greater than 65 years of age) revealed significantly lower left parietal metabolic ratios (left posterior parietal region divided by the hemispheric average) in the early-onset group. The metabolic ratio of posterior parietal cortex divided by the relatively disease-stable average of caudate and thalamus also separated patients with early-onset dementia from those with late-onset dementia, but not men from women. Further comparisons between sexes showed that, in all brain regions studied, the 9 postmenopausal women had higher nonweighted mean metabolic rates than the 15 men from the same age group, with hemispheric sex differences of 9% on the right and 7% on the left. These results demonstrate decreased parietal ratios in early-onset dementia of Alzheimer's disease, independent of a gender effect.

Memory impairments related to alcoholism and to age (young, middle, and old) were examined as a function of educational level (low, high). Factoring of 14 different memory test scores from 93 alcoholics and 73 controls into four components indicated that alcohol-related impairments in verbal memory were observed in adults with low, but not high levels of education. Similarly, age-related decrements in visual-spatial and verbal memory tasks (Components I and II) affected mainly low-education alcoholics and controls. On these components, age and alcoholism did not interact, but were additive. Effects of education were reflected in verbal but not nonverbal tasks (Auditory and Design Recognition, Components III and IV). Neither years of heavy drinking, lifetime consumption, nor abstinence (80% had7 wks abstinence) predicted component scores of alcoholics, while age or education accounted for significant variance in visual-spatial, verbal, and design recognition components.