Social cognition in siblings of patients with bipolar disorders

Identifying people at risk of developing bipolar disorder (BD) using endophenotypes is of recent interest. Few studies on social cognition in first-degree relatives of patients with BD have shown inconsistent findings. This study aimed to evaluate the social cognitive deficits (SCD) and its correlates among siblings of patients with BD.

In this cross-sectional study, patients of BD (n = 32), their siblings (n = 32), and healthy control (HC) subjects (n = 38) matched for age, gender, and education were evaluated on social cognition rating tools in Indian setting and neurocognitive tests (color trail test, Wisconsin card sorting test [WCST], and Hopkin's verbal learning test [HVLT]).

When the siblings of patients with BD were compared with patients with BD and the HCs, siblings (mean 0.6 [standard deviation [SD]: 0.2]) performed worse than the HCs (mean 0.9 [SD: 0.1]) (P ≤ 0.001) on the Faux pas composite index. Compared to HCs, siblings performed worse on all the subtests of HVLT (Trial delayed) (P < 0.001) and WCST (total correct, total errors, and conceptual responses) (P < 0.001).

Presence of elevated level of SCD among siblings, especially the Faux pas composite index in comparison to HCs, imply that these are stable traits, which are more often present in the patients and at risk individuals. This implies that SCD can be considered as another important endophenotype for BD.