Children at High and at Low Risk for Depression
Myrna M. Weissman, Bradley S. Peterson, Gerard Bruder, Craig Tenke, Jürgen Kayser, Virginia Warner, Priya Wickramaratne, Jamie Skipper, Jorge Alvarenga, Karen Abraham, Dan Alschuler
A 3-generation study of families at high and low risk for Major Depressive Disorder (MDD) has documented the strong familial transmission of mood disorders across generations. Six waves of assessments have been conducted in this cohort over 30 years. Our EEG collaboration started in the the 4th wave, and identified an asymmetry of EEG alpha indicative of right parietotemporal hypoactivity and a heightened anterior-to-posterior gradient of alpha in high-risk offspring having parents concordant for MDD (Bruder et al., 2005), and an alpha asymmetry in grandchildren with both a depressed parent and grandparent (Bruder et al., 2007). Magnetic Resonance Imaging (MRI) measures were added in the 5th wave, and found a remarkably robust association of familial risk for MDD with asymmetries in cortical thickness, with a nearly 30% reduction in thickness observed in the lateral parietal, temporal, and frontal cortices of the right hemisphere of the high risk group. Alpha power correlated inversely with cortical thickness, particularly over the right posterior region, indicating that EEG evidence of reduced cortical activity was associated with increased cortical thinning (Bruder et al., 2012). Both the MRI and EEG findings were present in high-risk individuals who never had MDD in their lifetimes, suggesting that these abnormalities were not simply a consequence of previously having been depressed or having been treated for depression. Thinning of the cortical mantle and reduced electrophysiological activity in the right hemisphere therefore may constitute related endophenotypes for familial vulnerability to developing MDD. In the current wave, our EEG montage has been greatly expanded (13 to 67 channels), affording the superior neurophysiological inferences possible using CSD. We have also added a visual half-field task, which identifies differences in the processing of affective pictures in participants at high risk for depression at a high temporal resolution.