Childhood trauma (CT) is a relevant environmental stressor for bipolar disorder (BP). Amygdala and hippocampus are key areas involved both in the pathophysiology of BP and in mediating the biological response to stress.

Structural neuroimaging studies help clarifying neural correlates of the relationship between BP diagnosis and CT.

To verify the impact of CT on amygdala and hippocampus and hippocampal subfields volumes in BP patients and healthy control (HC).

We assessed 105 outpatients, diagnosed with BPI or BPII according to DSM-IV-TR criteria, and 113 HC subjects. History of CT was obtained using the childhood trauma questionnaire (CTQ). High-resolution magnetic resonance imaging was performed on all subjects and volumes of amygdala, hippocampus, nucleus accumbens, caudate, pallidum, putamen, thalamus and hippocampal subfields were measured through FreeSurfer.

All deep gray matter structures were smaller in BP than HC. CT modulated the impact of the diagnosis on bilateral amygdala and hippocampus, in particular on subiculum, presubiculum and cornu ammonis CA1. It was associated with bilateral decreased volumes in HC and increased volumes in patients with BP.

Childhood trauma impacts on the amygdala and hippocampus, brain areas involved in response to stress and emotion processing, and specifically on the hippocampal subfields most implicated in learning trough positive/negative reinforcement.

The authors have not supplied their declaration of competing interest.