ELECTROENCEPHALOGRAPHIC SLEEP CORRELATES OF EPISODE AND VULNERABILITYTO RECURRENCE IN DEPRESSION

The study of electroencephalogram (EEG) sleep in depressed patients be fore and after treatment with psychotherapy can distinguish episode-re lated and persistent biological features. With longitudinal follow-up, we can also assess whether EEG sleep measures are associated with rec urrence of depression. In the current study, we examined EEG sleep dur ing the depressed state and during symptomatic remission after treatme nt with interpersonal psychotherapy in 42 outpatients with major depre ssion. Analyses included both visually-scored and computer-analyzed me asures. Patients showed significant increases in sleep latency (p = .0 1) and rapid eye movement (REM) latency (p = .04) from baseline to rem ission, as well as a decrease in REM sleep percent (p = .03). Total de lta EEG counts decreased from baseline to remission (p = .03), specifi cally in the second nonrapid eye movement (NREM) period (p = .03); as a result, the relative distribution of delta activity shifted toward s leep onset (i.e., increased delta sleep ratio; p = .03). Automated REM counts also decreased from depression to remission (p = .006). Compar ed to patients who remained well through one year of follow-up, those who suffered a recurrence of depression had less delta EEG activity at baseline and remission (p = .01), particularly in the lowest delta fr equency band of 0.5-1.0 Hz. Specific components of sleep (total delta activity, delta ratio, REM activity) constitute episode-related biolog ical features. Other components (slowest delta activity) may represent vulnerability factors for recurrence. (C) 1997 Society of Biological Psychiatry.