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Zusammenfassung:
The pattern of structural brain alterations associated with major
depressive disorder (MDD) remains unresolved. This is in part due to
small sample sizes of neuroimaging studies resulting in limited
statistical power, disease heterogeneity and the complex interactions
between clinical characteristics and brain morphology. To address this,
we meta-analyzed three-dimensional brain magnetic resonance imaging data
from 1728 MDD patients and 7199 controls from 15 research samples
worldwide, to identify subcortical brain volumes that robustly
discriminate MDD patients from healthy controls. Relative to controls,
patients had significantly lower hippocampal volumes (Cohen's d=-0.14, %
difference=-1.24). This effect was driven by patients with recurrent MDD
(Cohen's d=-0.17, % difference=-1.44), and we detected no differences
between first episode patients and controls. Age of onset <= 21 was
associated with a smaller hippocampus (Cohen's d=-0.20, %
difference=-1.85) and a trend toward smaller amygdala (Cohen's d=-0.11,
% difference=-1.23) and larger lateral ventricles (Cohen's d=0.12, %
difference=5.11). Symptom severity at study inclusion was not associated
with any regional brain volumes. Sample characteristics such as mean
age, proportion of antidepressant users and proportion of remitted
patients, and methodological characteristics did not significantly
moderate alterations in brain volumes in MDD. Samples with a higher
proportion of antipsychotic medication users showed larger caudate
volumes in MDD patients compared with controls. This currently largest
worldwide effort to identify subcortical brain alterations showed robust
smaller hippocampal volumes in MDD patients, moderated by age of onset
and first episode versus recurrent episode status.