Purpose: To determine the natural history of weight change and the occurrence of clinically significant weight loss in subjects with Alzheimer's disease (AD).
Patients and methods: Subjects with AD and cognitively normal older controls were recruited from 21 U.S. university medical centers that were participating in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Annual assessments were performed. Subjects with AD (n = 362) and controls (n = 317) with two or more weight measurements taken a year or more apart were included in this analysis. The average period of follow-up was > 2 years for both subjects with AD and controls. Four variables describing different aspects of weight change were defined: >/= 5% weigh loss, percent weight change/year, maximum percent weight loss over 1 year, and standard deviation of measurements/subject.
Results: Nearly twice as many subjects with AD experienced a weight loss of 5% or more when compared with controls (men P = .003 women P = .001). Surprisingly, a weight gain of 5% or more was also more common among AD cases. Overall, there was a tendency toward weight loss for both subjects with AD and controls, as measured by percent weight change/year. When other possible causes of weight loss were controlled using a multivariate model, a diagnosis of AD remained a significant predictor of >/= 5% weigh loss (P << .001), maximum percent weight loss over 1 year (P << .001), and standard deviation of measurements/subject (P << .001). A trend toward significance was noted for percent weight change/year (P = .07). Other than AD, very few of the possible confounders of this association remained significant predictors of weight change. In bivariate analysis, the severity of AD at entry correlated with percent weight change/year and standard deviation of measurements/subject. Additionally, the functional status of subjects with AD correlated with all four measures of weight change.
Conclusion: Clinically important weight loss occurs more frequently among patients with AD than among cognitively normal control subjects. Instances of weight gain, periods of acute weight loss, and greater fluctuations in weight suggest that the natural history of weight change in AD may be characterized by dysfunction in body weight regulation. Further analysis is warranted regarding the relationship of severity of dementia, functional status, and other specific aspects of AD to weight change.