EEG in 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers

EEG was examined in 348 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers. Both the percentage of infants exhibiting spectral peaks and the frequency in Hz at which those peaks were exhibited increased with age. Similarly, the EEG spectra showed a developmental increase in absolute power and a decrease in lower frequency and increase in higher frequency components. Infants of depressed mothers exhibited greater 8Hz lower 3Hz relative power and greater left frontal EEG log-absolute power than infants of non-depressed mothers. This profile was specially marked across a narrow frequency range which shifted from 3--9Hz to 4--9Hz by 3-months. Evaluation of 4 different asymmetry indices revealed that while both the log-absolute difference and the absolute ratio asymmetry indices best differentiated infants of depressed from infants of non-depressed mothers, the absolute ratio asymmetry index appeared to minimize within group variability. The significance of these findings are discussed.