Impairment of verbal learning and memory and executive function in unaffected siblings of probands with bipolar disorder

• Published in: Bipolar disorders Vol. 12; no. 6; pp. 647 - 656
• Main Authors: Kulkarni, Sandip, Jain, Sanjeev, Janardhan Reddy, YC, Kumar, Keshav J, Kandavel, Thennarasu
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2010
• Subjects: Adult; Age; Attention; Auditory discrimination learning; Auditory pathways; Bipolar disorder; Bipolar Disorder - complications; Bipolar Disorder - genetics; Case-Control Studies; Circuits; Cognition; Cognition Disorders - complications; Cognition Disorders - genetics; Cognitive ability; endophenotypes; Executive function; Female; genomics; Humans; Learning; Learning Disorders - complications; Learning Disorders - genetics; Male; Memory; Memory Disorders - complications; Memory Disorders - genetics; Multivariate analysis; neuropsychology; Siblings; Verbal Learning; verbal memory; Young Adult
• ISSN: 1398-5647; 1399-5618; 1399-5618
• DOI: 10.1111/j.1399-5618.2010.00857.x

Kulkarni S, Jain S, Janardhan Reddy YC, Kumar KJ, Kandavel T. Impairment of verbal learning and memory and executive function in unaffected siblings of probands with bipolar disorder.
Bipolar Disord 2010: 12: 647–656. © 2010 The Authors. 
Journal compilation © 2010 John Wiley & Sons A/S. Objectives:  Impairments in executive function and memory have been reported in relatives of patients with bipolar disorder, suggesting that they could be potential endophenotypes for genetic studies, but the findings are inconsistent. In this study, neuropsychological performance in unaffected siblings of probands with family loading for bipolar disorder is compared to that of individually matched healthy controls. We hypothesized that performance on tests of executive functions and memory would be impaired in unaffected siblings of probands with bipolar disorder compared to matched healthy controls. Methods:  We evaluated 30 unaffected siblings of probands with bipolar I disorder and 30 individually matched healthy controls using tests of attention, executive function, and memory. Unaffected siblings and healthy control subjects did not differ with respect to gender, age, and years of education. Results:  Unaffected siblings performed poorly on the Tower of London test (TOL), the Rey’s auditory verbal learning test (RAVLT), and the Rey’s complex figure test. In the multivariate analysis, significance was noted for the TOL, total number of moves (p = 0.007) and the RAVLT total learning score (p = 0.001). Conclusions:  Our study suggests that the deficits in verbal learning and memory and executive functions (planning) could be potential endophenotypes in bipolar disorder. These deficits are consistent with the proposed neurobiological model of bipolar disorder involving the frontotemporal and subcortical circuits. Future studies could couple cognitive and imaging strategies and genomics to identify neurocognitive endophenotypes in bipolar disorder.