Bipolar disorder (BD) is associated with cognitive and functional difficulties, persistent beyond mood episodes. Cognitive remediation (CR) is a psychological therapy targeting cognitive and functioning difficulties. Recent evidence suggests that CR may enhance long-term functioning but transfer mechanisms on functional outcomes have not been explored. We aim to investigate whether and how cognitive gains after CR transfer to functional improvement.

We considered data from a randomized controlled trial comparing CR (n = 40) to treatment-as-usual (TAU; n = 40) in euthymic people with BD. Treatment outcomes included individual cognitive domains and global cognition, psychosocial functioning, and goal attainment. Regression-based mediation and moderation modelling were used to assess whether and how post-treatment cognitive changes translate into functional improvement at follow-up, three months after treatment end.

Cognitive gains after CR transferred to functional changes three months later: improvement in post-treatment global cognition partially mediated the effect of CR on psychosocial functioning (standardized indirect effect: −0.23, 95% CI −0.51 to −0.04). Goal attainment was not significantly mediated by changes in cognition, but post-treatment cognitive performance moderated the effect of CR on the GAS at follow-up (interaction effect: 0.78, 95% CI 0.08–1.55).

Our findings suggest that cognitive improvements contribute to functional improvement but transfer mechanisms differ between psychosocial functioning and idiosyncratic recovery goals. Cognition accounted for only a proportion of the total CR effect on functional outcomes. Future studies should consider other variables, such as metacognition, that may drive the transfer of CR effects to functional outcomes.