Elisabeth Koss

The development of Alzheimer's disease (AD) later in life may be reflective of environmental factors operating over the course of a lifetime. Educational and occupational attainments have been found to be protective against the development of the disease but participation in activities has received little attention. In a case-control study, we collected questionnaire data about 26 nonoccupational activities from ages 20 to 60. Participants included 193 people with probable or possible AD and 358 healthy control-group members. Activity patterns for intellectual, passive, and physical activities were classified by using an adaptation of a published scale in terms of "diversity" (total number of activities), "intensity" (hours per month), and "percentage intensity" (percentage of total activity hours devoted to each activity category). The control group was more active during midlife than the case group was for all three activity categories, even after controlling for age, gender, income adequacy, and education. The odds ratio for AD in those performing less than the mean value of activities was 3.85 (95% confidence interval: 2.65-5.58, P < 0.001). The increase in time devoted to intellectual activities from early adulthood (20-39) to middle adulthood (40-60) was associated with a significant decrease in the probability of membership in the case group. We conclude that diversity of activities and intensity of intellectual activities were reduced in patients with AD as compared with the control group. These findings may be because inactivity is a risk factor for the disease or because inactivity is a reflection of very early subclinical effects of the disease, or both.

To assess the occurrence and related features of motor vehicle crashes in patients with dementia of the Alzheimer type (DAT) we studied 30 patients who had been followed longitudinally and 20 healthy age-matched control subjects. Data were gathered from first-degree relatives who had lived with the subjects for the previous 5 years or more. Forty-seven percent of the DAT patients incurred at least one crash while they were driving, whereas only 10% of the control subjects had had a crash in the previous 5 years. The odds ratio for crashes in the DAT group was 7.9 (p less than 0.01). Moreover, in 77% of DAT patients, a deterioration in driving performance was noted, and 63% of the patients had stopped driving. However, only 42% of the DAT patients who stopped driving did so before a crash occurred. Mean illness duration was 4.0 (+/- 1.8) years, and the mean Mini-Mental Status Examination score was 19.9 (+/- 6.3) at the time of the first crash in the DAT group. The occurrence of crashes was not significantly correlated with dementia severity or with disease duration. These data suggest that the occurrence of driving crashes in patients with DAT is an important public health problem.

Retrieval from semantic memory, measured by tasks requiring subjects to name items from a given category, was studied in mild Alzheimer-type dementia (Mild-ATD) subjects, moderate-to-severe Alzheimer-type dementia (MS-ATD) subjects, and normal controls. Semantic retrieval performance was shown to be highly sensitive to both the presence and the severity of ATD. Retrieval from both semantic categories and letter categories showed differences in the rate of production of correct responses between subject groups. These rate differences were not due to differences in accessibility of low-dominance semantic category members or low-frequency letter category members. An increase in errors as well as a decrease in correct responses contributed to the performance deficits of the ATD subjects. Furthermore, the pattern of errors changed from Mild- to MS-ATD. Qualitative as well as quantitative differences were also observed in the performance of Mild- versus MS-ATD groups on a third type of semantic retrieval task--the supermarket task. As performance of the ATD subjects declined on these semantic retrieval tasks, so did their performance on other tasks assessing primarily attention, language, and memory. The findings are discussed in terms of the progressive breakdown in both attentional and semantic memory functions which are associated with ATD.

Ten carefully screened men with very mild symptoms of Alzheimer's disease (AD) and ten healthy controls of similar age were compared on multiple chemosensory tasks: odor detection and identification, and taste detection. The patients scored significantly worse than controls on identification of odors and of a subset of airborne stimuli providing trigeminal stimulation. In contrast, the patients' olfactory detection thresholds as well as taste detection thresholds were not impaired relative to those of controls. The patients' scores on neuropsychological tests and the results 18F-2 deoxy-D-glucose PET studies did not correlate with any of the chemosensory measures. The isolated odor identification deficit suggests that the initial chemosensory impairment in AD is central rather than peripheral.