Positron emission tomography of reversible intellectual impairment induced by long-term anticholinergic therapy.

Long-term oral anticholinergic (AC) therapy can occasionally produce intellectual impairment. We investigated a patient with Parkinson's disease accompanied by intellectual impairment induced by long-term AC therapy. The intellectual impairment of the patient disappeared after cessation of AC therapy. Positron emission tomography (PET), during and after long-term oral AC therapy, revealed that it causes bilateral diffuse decrease of glucose metabolism in the cortex, basal ganglia, thalamus, hippocampus and cerebellum. Cessation of the therapy resulted in diffuse increase of glucose metabolism in all of the above regions. Cranial CT and magnetic resonance imaging (MRI) showed no abnormalities. Our results suggest that long-term AC therapy causes reversible bilateral diffuse glucose hypometabolism.