CSF cortisol in affective illness.

The few studies reported to date suggest that CSF cortisol is increased in depression and mania compared to normal subjects but that this increase is not specific to these disorders, since increased levels occur in other psychiatric and neurologic disorders. The CSF elevation is probably secondary to cortisol changes in the blood, but CSF levels appear to be more stable. The diurnal change in CSF may also be greater than that in blood. The significant correlation between CSF and blood levels observed in monkeys has not been found in humans. Future studies must control for time of day, as well as diagnostic factors, and ideally should include other measures of cortisol function, such as urinary excretion or the DST. Regulation of CSF cortisol is not well understood, and its relationship to other brain chemistries is unclear.