Changes in forebrain function from waking to REM sleep in depression: preliminary analyses of [F-18]FDG PET studies

Based on recent functional brain imaging studies of healthy human REM sleep , we hypothesized that alterations in REM sleep in mood disorder patients r eflect a functional dysregulation within limbic and paralimbic forebrain st ructures during that sleep state. Six unipolar depressed subjects and eight healthy subjects underwent separate [F-18]2-fluoro-2-deoxy-D-glucose ([F-1 8]FDG) PET scans during waking and during their first REM period of sleep. Statistical parametric mapping contrasts were performed to detect changes i n relative regional cerebral glucose metabolism (rCMRglu) from waking to RE M sleep in each group as well as interactions in patterns of change between groups. Clinical and EEG sleep comparisons from an undisturbed night of sl eep were also performed. In contrast to healthy control subjects, depressed patients did not show increases in rCMRglu in anterior paralimbic structur es in REM sleep compared to waking. Depressed subjects showed greater incre ases from waking to REM sleep in rCMRglu in the tectal area and a series of left hemispheric areas including sensorimotor cortex, inferior temporal co rtex, uncal gyrus-amygdala, and subicular complex than did the control subj ects. These observations indicate that changes in limbic and paralimbic fun ction from waking to REM sleep differ significantly from normal in depresse d patients. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.