Depression is associated with sleep disturbances, including alterations
in rapid eye movement (REM) sleep, that may relate to the neurobiology of
the disorder. Given that REM sleep activates limbic and anterior paralimbic
cortex and that depressed patients demonstrate increases in electroencephalographic
sleep measures of REM, we hypothesized greater activation of these structures
during waking to REM sleep in depressed patients.
Subjects completed electroencephalographic sleep and regional cerebral
glucose metabolism assessments during both waking and REM sleep using [18F]fluoro-2-deoxy-D-glucose positron emission tomography.
Patients and healthy subjects recruited from the general community to
participate in a research study of depression at an academic medical center.
Twenty-four unmedicated patients who met the Structured
Clinical Interview for DSM-IV criteria for current major depression
and who had a score of 15 or higher on a 17-item Hamilton Rating Scale for
Depression; 14 medically healthy subjects of comparable age and sex who were
free of mental disorders.
Main Outcome Measures
Electroencephalographic sleep, semiquantitative and relative regional
cerebral metabolism during waking and REM sleep.
Depressed patients showed greater REM sleep percentages. While both
healthy and depressed patients activated anterior paralimbic structures from
waking to REM sleep, the spatial extent of this activation was greater in
the depressed patients. Additionally, depressed patients showed greater activation
in bilateral dorsolateral prefrontal, left premotor, primary sensorimotor,
and left parietal cortices, as well as in the midbrain reticular formation.
Increased anterior paralimbic activation from waking to REM sleep may
be related to affective dysregulation in depressed patients. Increased activation
of executive cortex may be related to a cognitive dysregulation. These results
suggest that altered function of limbic/anterior paralimbic and prefrontal
circuits in depression is accentuated during the REM sleep state. The characteristic
sleep disturbances of depression may reflect this dysregulation.