Residual and Subsyndromal Bipolar Symptoms in Older Versus Younger Adults

• What is the primary question addressed by this study? What are the frequency and associated factors of residual and subsyndromal symptoms in older adults with bipolar disorder compared to younger adults? • What is the main finding of this study? The frequency of residual symptoms is similar between younger and older groups (84.9% vs. 84.8%), as is the frequency of subsyndromal symptoms (15.1% vs. 15.2%). Positive and negative stressful life events and social anxiety disorder are associated with residual symptoms. • What is the meaning of the finding? Early recognition of residual symptoms in older adults with bipolar disorder is essential for effective treatment and care. This cross-sectional study explored the frequency of residual and subsyndromal symptoms in older adults with bipolar disorder who are euthymic and compared to younger adults and factors associated with symptoms. Cross-sectional descriptive study. The Mayo Clinic Bipolar Disorder Biobank. Participants aged 18-80 years with bipolar disorder I or II disorder who were euthymic and were also evaluated on Bipolar Inventory of Symptoms Scale (BISS) for the frequency of residual and subsyndromal symptoms in the last week at time of enrollment. BISS residual (depressive score 1-15, mania score 1-9) and subsyndromal symptoms (depressive score 16-23, mania score 10-19) were compared between older (≥ 50 years old) and younger age groups using chi-square tests. Linear regression tested for association between demographic and clinical factors with BISS scores. A total of 126 patients were analyzed, with no significant differences found in the frequency of subsyndromal symptoms (15.1% in younger vs. 15.2% in older adults) or residual symptoms (84.9% in younger vs. 84.8% in older adults). In both age groups, worry/anxiety and insomnia were the most common residual depressive symptoms, while irritability was the most common residual manic symptom. In the full sample, positive and negative stressors were correlated with a higher BISS total score (τ = 0.25, p = 0.0015 and τ = 0.24, p = 0.0011, respectively). These factors were more associated with a higher BISS mania subscale score (τ = 0.28, p = 0.0007 and τ = 0.27, p = 0.0003, respectively). Those with social anxiety disorder also had 5.79 (95% CI 1.36, 10.21; p = 0.012) higher BISS total score than those without the disorder. The frequency of residual symptoms in older and younger adults with bipolar disorder, as measured by BISS, did not show a significant difference. Comorbid social anxiety disorder, and positive and negative stressors were associated with residual symptoms.