Relationship between changes of body mass index (BMI) and cognitive decline in Parkinson's disease (PD).

Decreased BMI has been reported that it may be associated with cognitive decline in the elderly. Weight loss is common in patients with PD. However, studies comparing cognitive changes according to BMI changes in PD have not been done yet. We performed this study to know a relationship between BMI changes and the rate of cognitive decline in PD. PD patients were recruited retrospectively. The patients (n=104) were divided into two groups according to BMI changes during initial 6 months of follow-up: decreased (n=52) vs. stable BMI groups (n=52). Cognitive functions were repeated until 36 months of follow-up using the Korean version of the Mini-Mental State Examination (K-MMSE) and the modified Mini-Mental State (3MS) test. We calculated the rate of cognitive decline (K-MMSE and 3MS score changes/month) and compared it between the two groups. The decreased BMI group showed lower level of cognitive function than that of stable BMI group, especially at the 36th month of follow-up (p<0.05). In addition, the rate of cognitive decline was also significantly faster in the decreased BMI group, particularly at the 36th month of follow-up (p<0.05). This study suggests that decreased BMI during initial 6 months of follow-up in PD might be a useful indicator for future risk of dementia and let clinicians predict faster rate of cognitive decline in patients with PD.