Molecular clock genes in man and lower animals: Possible implications for circadian abnormalities in depression

This paper reviews the recent discovery of clock genes that provide the mec hanism for the regulation of circadian and seasonal rhythms in lower organi sms and in humans and relates these clock genes to the circadian abnormalit ies in depression. (2) A subgroup of depressed patients have documented cir cadian abnormalities ill mood, sleep, temperature and neuroendocrine secret ion; (2) It is also suggested that season affective disorder (SAD) patients may show an abnormality in their ability to shift their daily circadian rh ythms in response to seasonal light changes; (3) The dramatic improvements in some depressions in response to three treatment modalities which manipul ate circadian rhythms suggest that circadian abnormalities reported in pati ents may constitute a core component of the pathophysiology in depression; (4) Mutations in clock genes have been discovered that accelerate ou delay circadian cycles; (5) It is hypothesized that 24-hour rhythm abnormalities in major depression and SAD may be due to altered clock genes. (C) 2000 Ame rican College of Neuropsychopharmacology. Published by Elsevier Science Inc .