Brain metabolic alterations herald falls in patients with Parkinson's disease.

Pathophysiological understanding of gait and balance disorders in Parkinson's disease is insufficient and late recognition of fall risk limits efficacious follow-up to prevent or delay falls. We show a distinctive reduction of glucose metabolism in the left posterior parietal cortex, with increased metabolic activity in the cerebellum, in parkinsonian patients 6-8 months before their first fall episode. Falls in Parkinson's disease may arise from altered cortical processing of body spatial orientation, possibly predicted by abnormal cortical metabolism.