Short-term memory in Parkinson's disease after withdrawal of long-term anticholinergic therapy.

We assessed the short-term memory (STM) using the Visual Paired Associates and the Verbal Paired Associates test, and the motor status at the end of 7.8 +/- 3.7 years of anticholinergic therapy in 22 nondemented patients with Parkinson's disease (PD). Eighteen patients managed to stop anticholinergic therapy. During anticholinergic therapy, STM in PD is significantly worse than in normal controls (CS). Two months after the withdrawal of anticholinergic drugs, the STM retest gain is significantly greater in PD than in CS, and at that time STM in PD did equal CS levels. After withdrawal of anticholinergic therapy, thirteen patients noticed a deterioration of motor function; the dose of levodopa had to be increased in seven patients. We conclude that in nondemented PD patients, long-term anticholinergic therapy probably does not result in irreversible damage to STM, and withdrawal of long-term anticholinergic therapy is feasible in the majority of PD patients.