Depressive disorders occur in Parkinson's disease in about 40 %. They
often manifest - not seldom preceding diagnosis of Parkinson's syndrom
e - like monopolar depression. Their cause has not yet been explained
in a satisfactory way. Neurotransmitter disturbances are discussed as
well as psychogenic factors. There seems to be a subtype of Parkinson'
s disease with more frequent depression, which is characterized by inc
reased rigidity and bradykinesia, lower age at onset and family histor
y of Parkinson's disease. Especially antidepressants, but also sleep d
eprivation and electroconvulsive therapy are efficient. The review is
illustrated by a case report.