Circulating leptin levels and weight loss in Alzheimer's disease patients

Weight loss is common in Alzheimer's disease (AD) and is predictive of mort ality. Leptin, an adipocyte-derived peptide hormone is implicated in the re gulation of satiety and energy expenditure. it acts on the hypothalamus to suppress appetite and increase energy expenditure. We undertook this study to determine if inappropriately elevated leptin levels play a role in AD-as sociated weight loss. Serum leptin levels of 8 patients in each of the foll owing groups were determined: (1) AD, body mass index (BMI) >25; (2) AD, BM I <20; (3) non-Alzheimer's (vascular) dementia (VaD), BMI >25, and (4) VaD, BMI <20. Mean serum leptin levels were significantly lower in below-approp riate-weight patients (both AD and VaD) than in appropriate-weight controls . Below-appropriate-weight AD patients had a significantly lower mean serum leptin concentration than appropriate-weight VaD controls. Weight loss is a feature of AD. Inappropriately elevated leptin levels do not appear to be implicated. Indeed, we have shown that the afferent limb of the leptin fee dback loop is intact in below-appropriate-weight AD patients and suggest hy pothalamic dysfunction may underlie this feature. Copyright (C) 2001 S. Kar ger AG, Basel.