Cognitive Impairment and Non-Invasive Neuromodulation Interventions in Bipolar Disorder: A Narrative Review of Current Status and Future Directions.

Bipolar disorder (BD) is a severe mental illness characterized by recurrent episodes of mania and depression. The disorder is associated with high rates of relapse and disability, significantly affecting patients' social functioning and quality of life. It is estimated that 30-50% of individuals with BD do not regain their premorbid level of social functioning, primarily due to persistent cognitive impairments. These cognitive deficits are prominent not only during acute episodes but also persist throughout remission, even when emotional symptoms have stabilized. Multiple studies have demonstrated that cognitive dysfunction is widely recognized as a key predictor of relapse, disease progression, and loss of social functioning in individuals with BD. An increasing body of research suggests that the long-term prognosis of BD is closely linked to cognitive impairment, establishing cognitive remediation as a central therapeutic goal for improving social functioning in this population. However, current pharmacological treatments for cognitive deficits show limited efficacy and are frequently associated with notable side effects. Non-pharmacological approaches, particularly neuromodulation techniques, are increasingly recognized for their potential to improve cognitive deficits in BD. This narrative review summarizes the latest findings on neuromodulation interventions for cognitive impairment in BD, with a focus on the current applications and future directions of non-invasive neuromodulation techniques.