Shortened REM latency as a psychobiological marker for psychotic depression? an age-, gender-, and polarity-controlled study

Background: Previous reports suggest that the clinical dichotomy separating psychotic and nonpsychotic depression corresponds to different neurobiological profiles. The aim of the present study is to further investigate the psychobiological correlates of these two particular depressive subtypes. Methods: Thyroid-stimulating hormone response to thyrotropin-releasing hormone postdexamethasone cortisol levels, and electroencephalgraphic sleep characteristics of 44 psychotic major depressive patients were compared to those of 44 nonpsychotic depressives matched for age, gender, and polarity. Results: Some biological disturbances usually associated with depression (increased wakefulness, diminished rapid eye movement latency, hypercortisolism, blunted thyroid-stimulating hormone response to thyrotropin-releasing hormone stimulation) seemed to be significantly more pronounced in the psychotic depressed group as a reflection of greater illness severity; however, shortened REM latency was not influenced by severity and seemed to be more specifically related to the co-occurrence of psychotic and depressive symptoms. Conclusions: Our data provide further support for the validity of the clinical dichotomy separating psychotic and nonpsychotic major depression independently of severity.