The potential for synergistic effect of non-invasive brain stimulation and cognitive behavioural therapy for depressive and cognitive outcomes in major depressive disorder: A scoping review.

BACKGROUND

Depression is a debilitating psychiatric disorder and a well-established modifiable risk factor for dementia. Beyond affective symptoms, depression is frequently associated with cognitive impairment that persists post-remission in 39-44% of cases. Non-invasive brain stimulation (NIBS) techniques, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), have demonstrated potential to induce neuroplasticity and reduce the affective burden of depression. When integrated with cognitive behavioural therapy (CBT), targeting cognitive restructuring to modify maladaptive thought patterns, these approaches may exert synergistic effects and alleviate affective symptoms while mitigating the risk of long-term cognitive decline.

METHODS

A scoping review was conducted following Joanna Briggs Institute and PRISMA-ScR guidelines. Medline, Scopus, APA PsycINFO, and Embase were searched for studies comparing combined rTMS-CBT or tDCS-CBT interventions to either modality alone. Eligible studies included adults (≥18 years) diagnosed with unipolar depressive disorders. Data on depression severity, cognitive outcomes, and baseline predictors were extracted and analyzed.

RESULTS

Analysis of eleven eligible studies consistently suggested that combination therapies produce greater reductions in affective symptoms than monotherapies. Improvements in cognitive outcomes, including executive functions, working memory, and social cognition, were reported exclusively in studies combining tDCS with CBT, as no identified rTMS-CBT studies formally assessed cognitive endpoints.. Age, sex, gender, and cognitive reserve were underreported as moderating factors.

CONCLUSIONS

Combined NIBS and CBT interventions may augment the treatment of affective symptoms. Future research should (1) standardize cognitive assessments, (2) include broader age cohorts to capture pre-dementia risk states, and (3) examine sex and gender as potential moderators.