Cognitive performance and psychosocial functioning in unaffected siblings of bipolar disorder patients in comparison with healthy controls.

We aimed to evaluate the cognitive domains for endophenotypes and their bearing on psychosocial functioning in unaffected siblings of patients with bipolar type I disorder (BD-I). We recruited unaffected siblings (n = 60) and age (±2 years), gender and education-matched healthy control subjects (n = 60) after screening with Structured clinical interview for DSM-IV-TR axis I disorders (SCID-I) - Research Version, Young Mania rating scale (YMRS), Hamilton depression rating scale (HDRS) and Family Interview for Genetic Studies scale (FIGS). Cognitive functioning was evaluated using Addenbrooke's Cognitive Examination III Revised (ACE-III R) and Trail making tests A and B, whereas psychosocial functioning was evaluated using the Social and Occupational Functioning Assessment Scale (SOFAS). The siblings had scored significantly lower in memory tasks of ACE-III R (p < 0.001) than controls, whereas other cognitive domains were comparable. Psychosocial functioning did not differ significantly between the groups. No correlation existed between cognitive performance and psychosocial functioning. Memory functions can be considered as a possible endophenotype for BD-I.