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

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.

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.

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.

This report presents empirical data suggesting a moderate impact of subthreshold symptoms on functioning/disability and QoL and a discrete impact on neuropsychological impairment.