Interleukine-6 serum levels correlate with response to antidepressant sleep deprivation and sleep phase advance.
Unstimulated production of interleukine-6 (IL-6) is known to be enhanced in patients affected by a major depressive episode. Recent studies supported a role for basal IL-6 levels in predicting response to antidepressant drug treatments. In a sample of 10 consecutively admitted drug-free bipolar depressed inpatients, we investigated the possible correlation between unstimulated pretreatment production of IL-6 and antidepressant response to a night of total sleep deprivation (TSD) followed by a night of sleep phase advance (SPA), a nonpharmacologic treatment which is known to rapidly improve depressive symptomatology. Changes in perceived mood during treatment were recorded with self-administered Visual Analogue Scales (VAS). We observed a significant inverse correlation between IL-6 serum levels and VAS scores after treatment, meaning that higher IL-6 values before treatment were associated with worse response. This finding is in agreement with previous studies about amitriptyline and lithium antidepressant treatments. Our preliminary finding confirms the clinical value of IL-6 baseline concentration as a predictor of response to antidepressant treatment.