alpha(2)-Adrenergic agonist clonidine for improving spatial working memoryin Parkinson's disease

The loss of dopaminergic cells during Parkinson's disease (PD) produces "fr ontal"-like impairment in spatial working memory (SWM) and planning functio ns. This study investigated whether an alpha(2)-adrenergic agonist, clonidi ne (0.5 or 2 mu g/kg, orally), improves SWM, spatial shortterm or spatial r ecognition memory, and planning functions in PD patients. Clonidine 2 mu g/ kg decreased errors in SWM, but a lower dose, 0.5 mu g/kg, had no effect on performance. Clonidine 0.5 and 2 mu g/kg failed to improve the strategy us ed to solve the SWM test. Clonidine 0.5 and 2 mu g/kg had no effect on accu racy of performance in the other tests. These results showed that clonidine improves performance in a test of SWM and that this is not due to improved spatial short-term or spatial recognition memory or planning functions. Th e authors suggest that stimulation of alpha(2)-adrenoceptors improves the m nemonic processing required for accurate SWM performance in PD patients.