Influence of pre-treatment structural brain measures on effects of action-based cognitive remediation on executive function in partially or fully remitted patients with bipolar disorder

Cognitive impairment is an emerging treatment target in patients with bipolar disorder (BD) but so far, no evidence-based treatment options are available. Recent studies indicate promising effects of Cognitive Remediation (CR) interventions, but it is unclear who responds most to these interventions. This report aimed to investigate whether pre-treatment dorsal prefrontal cortex (dPFC) thickness predicts improvement of executive function in response to Action-Based Cognitive Remediation (ABCR) in patients with BD. Complete baseline magnetic resonance imaging (MRI) data were available from 45 partially or fully remitted patients with BD from our randomized controlled ABCR trial (ABCR: n = 25, control group: n = 20). We performed cortical reconstruction and volumetric segmentation using FreeSurfer. Multiple linear regression analysis was conducted to assess the influence of dPFC thickness on ABCR-related executive function improvement, reflected by change in the One Touch Stocking of Cambridge performance from baseline to post-treatment. We also conducted whole brain vertex wise analysis for exploratory purposes. Groups were well-matched for demographic and clinical variables. Less pre-treatment dPFC thickness was associated with greater effect of ABCR on executive function (p = 0.02). Further, whole-brain vertex analysis revealed an association between smaller pre-treatment superior temporal gyrus volume and greater ABCR-related executive function improvement. The observed associations suggest that structural abnormalities in dPFC and superior temporal gyrus are key neurocircuitry treatment targets for CR interventions that target impaired executive function in BD.