Structural and functional abnormalities in elderly patients clinically recovered from early- and late-onset depression

Background: Structural and functional brain changes have been described in elderly patients with unipolar affective disorder. Changes appear to be more marked in patients with late-onset depression, but the reversibility of such changes after clinical recovery is not known. Methods: Magnetic resonance imaging, electroencephalography (EEG), and cognitive tests were performed in 23 elderly patients (mean age 66.5 years) clinically recovered from major depression. Twelve had late-onset depression (first episode over 55 years of age); 11 had early onset (first episode before 50 years). EEG and cognitive testing were also performed on 15 control subjects. Results: Patients with late-onset depression had larger third and lateral ventricles, increased ventricular–brain ratio, and greater frequency and severity of subcortical white matter lesions than those with early onset. There was no difference between early- and late-onset patients in EEG and cognitive measures, but compared with controls patients showed significant changes in EEG evoked potentials and increased slow-wave activity, slowed reaction times, and global impairments in cognitive function. Conclusions: These results suggest that structural changes are greater in patients with late-onset depression, and that EEG and cognitive impairments persist after recovery, regardless of age of onset of depression, and are independent of structural changes.