A state-of-the-art review of the many cognitive, affective, and behavioral dysfunctions associated with movement disorders. These dysfunctions include depression, dementia, psychosis, sleep disorders arising from Parkinson's and Huntington's disease, Tourette's syndrome, as well as multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, and many other related disorders. The authors describe these behavioral syndromes and their neurophysiological and neuropathological substratum, as well as their diagnostic criteria and therapeutic guidelines. The cognitive and affective dysfunctions are spelled out in detail.