The personality associated with Parkinson's disease.

Since at least 1913 reports have suggested there are personality traits and behaviors that are found premorbidly in those who go on to develop Parkinson's disease (PD). This premorbid personality consists of traits such as industriousness, punctuality, inflexibility, cautiousness, and lack of novelty seeking and persists after the onset of the motor illness. The existence of this personality remains controversial but is supported by case-based anecdotes, twin studies, and comparison of patients with PD with medical control patients on standardized instruments. In addition a large number of epidemiologic studies show that people who develop PD have low lifetime risks for cigarette smoking, coffee drinking, and alcohol consumption, again suggesting that there is a behavior pattern that predates PD. Despite the retrospective nature of much of these data, the use of nonstandardized instruments, and diffuse concepts of personality, the great majority of studies show striking similarity in identifying these traits. An integrating hypothesis, involving damage to dopaminergic systems, known to predate the onset of the motor illness, is discussed.