Subthreshold symptoms in bipolar disorder: Impact on neurocognition, quality of life and disability

Objective: To provide empirical evidence of the effect of subthreshold symptomatology (both depressive and manic) on psychosocial functioning, neurocognition and quality of life in bipolar disorder. Methods: A total of 133 participants were enrolled for this study (bipolar patients, n = 103; healthy controls, n = 30). Patients were divided into two groups according to their levels of subthreshold symptomatology: the subsyndromic group was constituted by those patients with upper levels of subthreshold symptomatology (HDRS >= 4 and YMRS >= 3) and the asymptomatic group represented the patients with lower scores (HDRS <= 3 and YMRS <= 2). All participants were administered a comprehensive neuropsychological battery. Moreover the patients answered the SF-36 (Quality of Life, QoL) and were interviewed with the WHODAS-2 (Psychosocial functioning and disability). One-way ANOVA were used in order to compare the differences between the three groups. Results: The analyses revealed that both patients groups, albeit free of acute symptoms of mania or depression, differed in terms of functioning and disability assessed with the WHODAS-2. Specifically, the total global score of disability was higher for the subsyndromic group indicating more impairment (p = 0.008). The same pattern of impairment was found for three of its domains: understanding and communicating (p = 0.013); self-care (p = 0.035) and getting along with others (p = 0.024). The subsyndromic group also scored lower when compared to their counterparts in the Mental Component of QoL of the SF-36 (p = 0.045). Finally, in the neuropsychological performance verbal learning and memory was found to be impaired regardless the levels of subthreshold symptomatology, suggesting that this variable is a robust indicator of neuropsychological impairment in BD patients. Conclusions: This report presents empirical data suggesting a moderate impact of subthreshold symptoms on functioning/disability and QoL and a discrete impact on neuropsychological impairment. (C) 2011 Elsevier B.V. All rights reserved.