Energy requirements in Alzheimer's disease patients

Weight loss in Alzheimer's patients has been observed by many clinicians and reported in the international geriatric literature. It represents a puzzling challenge for clinicians and researchers, and it is an important issue for caregivers and nursing home staff concerned with state and federal requirements for nutrition and weight monitoring. Using indirect calorimetry, we studied the resting energy expenditure of 21 elderly patients; 12 were residing in a community setting, and 9 were institutionalized. Of the 12 community-living patients studied, 5 had early to moderate Alzheimer's disease, and 7 were nondemented control subjects. Of the 9 institutionalized patients, all were severely demented, bedridden, and fed exclusively by gastric tube in a closely monitored clinical environment with daily bedside weighing. Four had Alzheimer's disease, and 5 had multi-infarct dementia (MID). Among the outpatients, the Alzheimer's group showed increased energy requirements (p = 0.028) and a significantly different pattern of fat-free mass compared with control subjects (p = 0.031). These observations on community-residing elderly were consistent with, and extended by our findings on energy requirements of, the demented institutionalized patients. The calorie intake necessary for weight maintenance of the bedridden institutionalized patients was determined during their prolonged institutionalization. The presumed maintenance level of calorie intake was then verified during a 10 wk study. During the 10 wk, we documented no significant change in weight with constant energy intake. Compared with MID patients, Alzheimer's patients tended to weigh less (52.84 vs 56.4 kg; p = 0.20) but actually required more calories (1626 vs 1341 kcal, p < 0.011).(ABSTRACT TRUNCATED AT 250 WORDS)