Electrophysiological changes in late life depression and their relation to structural brain changes

Background: Late life depression is often accompanied by slowed information processing during neuropsychological testing, and this has been related to underlying cerebrovascular disease. We investigated whether changes in electrophysiological markers of information processing might share the same pathological correlates. Methods: Differences in power spectra frequency, contingent negative variation (CNV), post-imperative negative variation (PINV), and auditory P300(a) amplitude and latency in 19 patients with DSM-IV major depression aged >= 60 years were compared with 25 recordings in age-matched healthy controls. Associations with total brain volume and degree of white matter hyperintensities (WMH) were examined in those who had undergone additional magnetic resonance imaging (MRI). Results: Compared with healthy controls, patients had more slow-wave delta (group difference: p=0.024) and theta activity (p=0.015) as well as alpha activity (p=0.005) but no decrease in beta band frequency (p=0.077). None of these changes related differently to brain volume or WMH in patients or controls. Patients further showed prolonged P300(a) latencies (p=0.027), which were associated with decreased total brain volume in patients but not controls (interaction by group: p=0.004). While there were no overall differences in PINV between both groups, patients showed a decrease in PINV magnitude with increasing WMH, a relation that was not seen in controls (interaction by group: p=0.024). Conclusion: Patients with late life depression show changes in several electrophysiological markers of cerebral arousal and information processing, some of which relate to brain atrophy and WMH on MRI.