Suicidal ideation and cognitive function: a comparative study in adolescents with unipolar versus bipolar depression

Suicidal ideation (SI) is highly prevalent in patients with depression and is closely associated with cognitive impairment. However, research focusing on this association within the adolescent population remains limited. Accordingly, this study aimed to investigate differences in SI levels and cognitive function between adolescents with unipolar depression (UD) and bipolar depression (BD), while further elucidating the associations between specific cognitive domains and SI.

This study recruited 326 adolescents with UD or BD. The Hamilton Depression Rating Scale (HAMD), Positive and Negative Suicidal Ideation Scale (PANSI), Insomnia Severity Index Scale (ISI), Internet Addiction Test (IAT), Positive and Negative Syndrome Scale Positive Subscale (PANSS-P), and Chinese Brief Cognitive Test (C-BCT) were used to assess depression, SI, insomnia, internet addiction (IA), psychotic symptoms, and cognitive function, respectively. Additionally, stepwise linear regression analysis was performed to identify independent factors associated with SI.

Compared to the UD group, adolescents with BD demonstrated significantly higher scores on the HAMD, PANSI, IAT, and PANSS-P, alongside lower performance in attention, working memory, and executive function. Regression analysis identified HAMD score and working memory as independent correlates of SI in the UD group. In contrast, SI in the BD group was independently associated with females, HAMD score, IAT score, and working memory.

Given the cross-sectional design, determining causality from these findings is not feasible.

Adolescents with BD may exhibit more severe SI and greater cognitive impairment than those with UD. Across both groups, SI was strongly associated not only with clinical symptoms such as depression and IA but also with cognitive deficits, particularly in working memory. However, multicenter longitudinal studies are still needed to validate these findings.