Cognitive skill learning in healthy older adults after 2 months of double-blind treatment with piribedil.

Abstract

Cognitive skill learning, as assessed by repeated testing on the Tower of Toronto (TT) task, has been found to be impaired in normal aging. There is evidence that this impairment might be accounted for by the well-documented, age-dependent decline of dopamine D2-like receptor availability. This study was an investigation of whether the D2/D3 dopaminergic agonist piribedil improves cognitive skill learning in older adults. Healthy elderly volunteers were assessed using the TT paradigm. Subjects were evaluated at baseline, and after 2 months of a placebo or piribedil (50 mg daily) treatment in a double-blind, crossover design. Two components of cognitive skill learning were considered--the ability to learn to solve the puzzle and the acquisition of a problem-solving routine. Piribedil showed a beneficial effect on the acquisition of a problem-solving routine, depending on the age of subjects, as revealed by solution reliability indexes measures. The effect of piribedil on the ability to learn to solve the puzzle was found to be dependent on the subject's working memory capacities. The present results suggest that piribedil is likely to enhance cognitive skill learning in healthy older adults and give further evidence that age-related dopamine decline plays an important role in cognitive impairment occurring in normal aging.