Demonstrating test-retest reliability of electrophysiological measures for healthy adults in a multisite study of biomarkers of antidepressant treatment response.

Growing evidence suggests that loudness dependency of auditory evoked potentials (LDAEP) and resting EEG alpha and theta may be biological markers for predicting response to antidepressants. In spite of this promise, little is known about the joint reliability of these markers, and thus their clinical applicability. New standardized procedures were developed to improve the compatibility of data acquired with different EEG platforms, and used to examine test-retest reliability for the three electrophysiological measures selected for a multisite project-Establishing Moderators and Biosignatures of Antidepressant Response for Clinical Care (EMBARC). Thirty-nine healthy controls across four clinical research sites were tested in two sessions separated by about 1 week. Resting EEG (eyes-open and eyes-closed conditions) was recorded and LDAEP measured using binaural tones (1000 Hz, 40 ms) at five intensities (60-100 dB SPL). Principal components analysis of current source density waveforms reduced volume conduction and provided reference-free measures of resting EEG alpha and N1 dipole activity to tones from auditory cortex. Low-resolution electromagnetic tomography (LORETA) extracted resting theta current density measures corresponding to rostral anterior cingulate (rACC), which has been implicated in treatment response. There were no significant differences in posterior alpha, N1 dipole, or rACC theta across sessions. Test-retest reliability was .84 for alpha, .87 for N1 dipole, and .70 for theta rACC current density. The demonstration of good-to-excellent reliability for these measures provides a template for future EEG/ERP studies from multiple testing sites, and an important step for evaluating them as biomarkers for predicting treatment response.

An everyday activity as a treatment for depression: the benefits of expressive writing for people diagnosed with major depressive disorder.

BACKGROUND: The benefits of expressive writing have been well documented among several populations, but particularly among those who report feelings of dysphoria. It is not known, however, if those diagnosed with Major Depressive Disorder (MDD) would also benefit from expressive writing. METHODS: Forty people diagnosed with current MDD by the Structured Clinical Interview for DSM-IV participated in the study. On day 1 of testing, participants completed a series of questionnaires and cognitive tasks. Participants were then randomly assigned to either an expressive writing condition in which they wrote for 20 min over three consecutive days about their deepest thoughts and feelings surrounding an emotional event (n=20), or to a control condition (n=20) in which they wrote about non-emotional daily events each day. On day 5 of testing, participants completed another series of questionnaires and cognitive measures. These measures were repeated again 4 weeks later. RESULTS: People diagnosed with MDD in the expressive writing condition showed significant decreases in depression scores (Beck Depression Inventory and Patient Health Questionnaire-9 scores) immediately after the experimental manipulation (Day 5). These benefits persisted at the 4-week follow-up. LIMITATIONS: Self-selected sample. CONCLUSIONS: This is the first study to demonstrate the efficacy of expressive writing among people formally diagnosed with current MDD. These data suggest that expressive writing may be a useful supplement to existing interventions for depression.

Reduced sustained brain activity during processing of positive emotional stimuli in major depression.

BACKGROUND: This study examines the directionality and temporal specificity of brain activity during sustained processing of emotional stimuli in individuals with current major depressive disorder (MDD) and nondepressed control participants. METHODS: Slow wave (SW) components of the event-related brain potential (ERP) were recorded from 16 control participants and 15 participants with MDD during a working memory task. During the task, individuals were shown a positive, neutral, or negative word and were asked to maintain it in memory for 5 sec. Participants then saw a letter and had to decide whether it was a part of the previously presented word. The ERP components were measured from nine scalp sites (F3, Fz, F4, C3, Cz, C4, P3, Pz, P4) during the encoding of emotional words. RESULTS: Compared with control individuals, MDD participants exhibited decreased brain responses to positive relative to negative or neutral stimuli. This decrease in brain activity during processing of positive information was evident across all sites and SW components. CONCLUSIONS: Our findings suggest that cognitive deficits in MDD may stem from diminished brain responses during processing of positive information and may not be associated with an augmented response to negative stimuli.

A CNV-distraction paradigm in combat veterans with posttraumatic stress disorder.

Fourteen veterans with posttraumatic stress disorder (PTSD) and 14 without PTSD participated in a contingent negative variation (CNV)-distraction paradigm. Subjects were instructed to press a button after hearing a high-pitched tone (S2) preceded by a low-pitched tone (S1). One-half of the trials included a white-noise distracter placed in the S1-S2 interval. Posttraumatic stress disorder subjects had larger frontal, but smaller central and parietal CNVs, regardless of condition (distracter, no distracter) or epoch (early CNV, late CNV). In PTSD subjects, the N1/P2 complex was smaller to warning (S1) and distracter stimuli and did not show the extent of facilitation present in non-PTSD subjects. Findings highlight PTSD-related differences in phasic cortical excitability and attention.