A double-blind, placebo-controlled study was conducted in 20 elderly patients with dementia associated with diffuse cerebrovascular disease to determine the effects of papaverine on the electrical activity of the brain. Frequency spectrum analysis of electroencephalograms showed the mean electrical content of the delta-theta band (0 to 7.5 Hz) was decreased significantly and content of the alpha band (7.6 to 12.5 Hz) was increased significantly from baseline. The changes in electroencephalographic activity observed in this study suggest that papaverine favorably affects neuronal metabolism, possibly through improved perfusion of the tissue, although the exact mechanism of action remains unknown.