Faculty Bibliography

Neuropathologic changes in the temporal lobe, including focal atrophy of the subiculum and entorhinal cortex, have been described in association with Alzheimer disease. We studied the usefulness of detecting temporal-lobe structural changes on CT in making the diagnosis of Alzheimer disease. The dementia imaging protocol we use includes thin-section (5 mm) cuts of the temporal lobe oriented 20 degrees negative (caudal) to the plane of the canthomeatal line. Thirty-four patients with suspected Alzheimer disease and 20 normal elderly control subjects, all between 65 and 80 years old, were studied with a standard protocol that also included neurologic and medical examinations and detailed psychometric testing. All the temporal-lobe evaluations of the five variables measured were significantly associated with the presence or absence of Alzheimer disease. Almost all Alzheimer patients showed evidence of mild or greater severity of overall temporal-lobe atrophy. The absence of temporal-lobe atrophy, seen in approximately one half the normal cases, identified normal individuals with a high degree of specificity (95%). The presence of characteristic hippocampal lucency, apparently due to enlargement of the choroid and hippocampal fissures, showed the highest sensitivity and classification accuracy of all the variables tested (82 and 80% respectively; p less than .001), correctly identifying 82% of Alzheimer patients and 80% of Alzheimer patients and control subjects. These results indicate that CT detection of structural changes in the temporal lobe and hippocampus strongly support the diagnosis of Alzheimer disease. A temporal-lobe imaging protocol for CT, and by extension for MR, is suggested for the evaluation of patients with the clinical diagnosis of a dementing disorder

A series of studies published over the past 6 years now permit a relatively precise description of the temporal course of Alzheimer's disease (AD). Initially, 7 global stages of CNS aging and AD were described. Subsequently, data on the stage specific relationship between these stages and widely employed mental status, psychometric, and other assessment measures were collected. Longitudinal studies helped to clarify the borders between normal CNS aging and AD using these measures. Other studies described functioning and self-care correlates of the 7 global stages. These were ultimately divisible into 16 clearly defined, ordinal functional stages. Empirical longitudinal observations permitted the description of the mean temporal course of each of the 16 functional stages of aging and AD. The cross-sectional stage specific data on mental status and other measures can now be applied to the mean temporal course observations and the validity of the temporal estimates forwarded can be investigated in detail. Etiologic hypotheses based upon the observed phenomenologic and temporal course of AD are discussed

A 3-year longitudinal study was conducted with 50 Alzheimer's disease patients and 45 elderly control subjects. All study participants received an extensive evaluation that included brain CT at baseline and follow-up. Quantitation of ventricular size, using both linear and volume methods, revealed highly significant cross-sectional and longitudinal differences between the Alzheimer patients and control subjects. Specifically, the annual rate of change in ventricular volume was approximately 9% in the Alzheimer patients and approximately 2% in the controls. The presence of age-related white matter lesions had no effect on the clinical course of the patients or on the changes in ventricular size. Among the Alzheimer patients, the rate of clinical decline was strongly related to the rate of change in ventricular size. Baseline ventricular measurements were of no value in predicting the subsequent rate of clinical deterioration or ventricular enlargement. The results suggest that changes in ventricular size closely reflect the clinical changes in Alzheimer patients