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Hot Publication - Lotrich & Germain

Decreased Delta Sleep Ratio and Elevated Alpha Power Predict Vulnerability to Depression during Interferon-Alpha Treatment
Lotrich FE and Germain A
Acta Neuropsychiatrica, Published online 

Although poor sleep sometimes accompanies depression, it is unknown which specific sleep abnormalities precede depression.  Drs. Francis Lotrich and Anne Germain prospectively determined which specific aspect of sleep could predict the future and subsequent development of depression.

Drs. Lotrich and Germain examined two nights of polysomnography with quantitative electroencephalography from 24 adult, euthymic (not depressed) subjects – all subsequently treated with IFN-α for hepatitis C.  IFN- α is known to trigger depression in a subset of people.  The Beck Depression Inventory-II (BDI-II) excluding the sleep question, given every two weeks, was used to determine the maximal increase in depression symptoms.

The investigators found that the delta sleep ratio (an index of early-night restorative delta power) was inversely associated with increased BDI-II symptoms, as was elevated alpha power.  Both delta and alpha power exhibited high between-night correlations.  In addition, using a mixed-effect repeated-measure analyses, Drs. Lotrich and Germain observed an interaction between alpha power and the delta sleep ratio; subjects with low alpha power and an elevated delta sleep ratio were resilient to developing depression.  Most other sleep parameters – including total sleep time and percentage of time in slow wave sleep – were not associated with subsequent changes in depression.  Their findings suggest that both a high delta sleep ratio and low alpha power may be specific indices of resilience. As most other aspects of sleep were not associated with resilience or vulnerability, sleep interventions to prevent depression may need to specifically target these specific sleep parameters.

Contributors:
Francis E. Lotrich, MD, PhD and Anne Germain, PhD (University of Pittsburgh Department of Psychiatry)

This article appeared in the December 2014 issue of Acta Neuropsychiatrica.  The abstract is available here.