Most patients with dementia lose body weight over the course of the disease. Yet it is not known whether this weight loss is predominantly in the form of fat-free mass (FFM) or fat mass (FM), the latter of which one would expect if the weight loss were caused simply by a chronic decrease of energy intake.

To determine body composition and nutritional risk in geriatric patients and their association with cognitive function.

A retrospective, cross-sectional single-center database analysis.

We analyzed 4,095 consecutive geriatric hospital patients for body composition, nutritional risk, need of care and cognitive function using bioelectric impedance analysis, NRS 2002, Barthel Index and Mini Mental State Examination.

Subjects with cognitive dysfunction showed significant lower body weight, body mass index (BMI), FM, fat mass index, FFM and fat-free mass index and a higher NRS score compared to cognitively intact subjects. Mean body weight decreased 10.2%, mean FM decreased 21.1%, mean FFM decreased 5.9% and mean NRS 2002 score increased from 2.1 to 3.0 points with increasing cognitive deterioration. A multivariate analysis revealed that cognitive dysfunction, age and female gender were all significant risk factors for a low body mass index and a low fat mass index. Age, male gender and need of care, but not cognitive dysfunction, were risk factors for a low fat-free mass index.

Dementia patients seem to lose predominantly fat mass with weight loss. Female dementia patients are at a higher nutritional risk than male patients, presumably as a result of their different social situation in old age. That is why the nutritional state of female patients with dementia requires special attention.