Corpus callosum integrity is affected by mood disorders and also by the suicide attempt history: A diffusion tensor imaging study

•Corpus callosum (CC) is altered in bipolar disorders (BD).•Genu and body CC areas are altered in BD without suicide Attempt (SA).•History of SA exerts also a specific effect on CC integrity.•Splenium is specifically altered in SA independently from psychiatric status.•Screening for history of SA is crucial in future analyses of CC in affective disorders.

BackgroundSome MRI studies have noted alterations in the corpus callosum (CC) white matter integrity of individuals with mood disorders and also in patients with suicidal behavior. We investigated the specific impact of suicidal behavior on CC integrity in mood disorders.MethodsCC structural changes were assessed by diffusion tensor imaging (DTI) in 121 women 18-50-year-old): 41 with bipolar disorder (BD), 50 with major depressive disorder (MDD) and 30 healthy controls (HC). Fractional anisotropy (FA) and DTI metrics were calculated for the genu, body and splenium of CC and compared in the three groups by MANCOVA. Then, they were re-analyzed relative to the suicide attempt history within the MDD and BD groups and to the suicide number/severity.ResultsFA values for the CC genu and body were lower in non-suicide attempters with BD than with MDD and in HC. Conversely, FA values for all CC regions were significantly lower in suicide attempters with BD than in HC. Finally, higher number of suicide attempts (>2) and elevated Suicidal Intent Scale score were associated with significant splenium alterations.LimitationsLimitations include the cross-sectional design (non-causal study), the potential influence of medications and concerns about the generalizability to men.ConclusionGenu and body are altered in non-suicide attempters with BD, while splenium is specifically altered in suicide attempters, independently from their psychiatric status. History of suicide attempts may be a source of heterogeneity in the association between CC alterations and BD and may partially explain the variable results of previous studies.