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

Abstract

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.