[Neurobiological findings in a patient with 48-hour rapid cycling bipolar affective disorder. A case report].

Forty-eight-hour rapid cycling is a rare subclass of affective disorders and entails a regular periodic change of moods. The following case study describes the symptoms, therapy, and outcome of a patient suffering from daily switching between mania and depression along with neurobiological findings correlated to the affective cycles. We found alternating reduction and prolongation of sleep duration during manic and depressive days as well as differences in the amount of REM sleep. Cortisol secretion was regularly increased during depressive days. Regarding thyroid-stimulating hormone (TSH) secretion, the circadian rhythm was absent on depressive days. However, the glucose metabolic rate as measured by positron emission tomography (PET) did not differ on manic and depressive days. The patient reached almost complete remission under treatment with lithium.