The alpha(2) agonist, clonidine, improves spatial working memory performance in Parkinson's disease

Previous work has shown that the dopaminergic defect in Parkinson's disease is involved, to some extent, in the "frontal"-like impairment in spatial w orking memory and attentional set-shifting functions. We investigated wheth er an alpha(2) agonist, clonidine (0.5 and 2 mu g/kg, per os), could allevi ate spatial working memory and attentional set-shifting defect in Parkinson 's disease patients. We observed that 2 mu g/kg clonidine stimulated spatia l working memory accuracy, but had no effect on attentional set shifting or Visual recognition memory. Clonidine was also effective in stimulating spa tial working memory after withdrawal of dopaminergic drugs, and when this w as done, its effect was greater in severe Parkinson's disease patients. In contrast, clonidine failed to stimulate Visual recognition memory. These results suggest that disrupted activation of alpha(2) adrenoceptors m ay contribute to the impairment of spatial working memory in Parkinson's di sease. (C) 1999 IBRO. Published by Elsevier Science Ltd.