ENERGY-REQUIREMENTS IN ALZHEIMERS-DISEASE PATIENTS

Weight loss in Alzheimer's patients has been observed by many clinicia ns and reported in the international geriatric literature. It represen ts a puzzling challenge for clinicians and researchers, and it is an i mportant issue for caregivers and nursing home staff concerned with st ate and federal requirements for nutrition and weight monitoring. Usin g indirect calorimetry, we studied the resting energy expenditure of 2 1 elderly patients; 12 were residing in a community setting, and 9 wer e institutionalized. Of the 12 community-living patients studied, 5 ha d early to moderate Alzheimer's disease, and 7 were nondemented contro l subjects. Of the 9 institutionalized patients, all were severely dem ented, bedridden, and fed exclusively by gastric tube in a closely mon itored clinical environment with daily bedside weighing. Four had Alzh eimer's disease, and 5 had multi-infarct dementia (MID). Among the out patients, the Alzheimer's group showed increased energy requirements ( p = 0.028) and a significantly different pattern of fat-free mass comp ared with control subjects (p = 0.031). These observations on communit y-residing elderly were consistent with, and extended by our findings on energy requirements of, the demented institutionalized patients. Th e calorie intake necessary for weight maintenance of the bedridden ins titutionalized patients was determined during their prolonged institut ionalization. The presumed maintenance level of caloric intake was the n verified during a 10 wk study. During the 10 wk, we documented no si gnificant 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 kca l, p < 0.011). Calorie intake of the institutionalized Alzheimer's pat ients was 30.89 kcal/kg compared to 23.18 kcal/kg in the MID control s ubjects (p < 0.001). These data indicate that energy requirements are greater for Alzheimer's patients than for MID or nondemented control s ubjects of similar size. The differences appear to be the result of in creased lean-body mass in Alzheimer's patients. Further studies are ne cessary to elucidate the mechanisms leading to their altered body comp osition.