Cognitive Improvements from Adjunct Therapy with Transcranial Magnetic Stimulation are Short-Lived In Patients with Remitted Bipolar Disorder

Objectives: Repetitive transcranial magnetic stimulation (rTMS) has been used as an adjunct therapy to improve the cognitive abilities of patients with remitted bipolar disorder (BPD). This is accomplished through functional brain activity alterations. However, there is limited information about the duration and persistence of cognitive improvements. Investigate the long-term cognitive effects (four weeks) of adjunct treatment with rTMS in patients with remitted BPD. Methods: Patients with remitted BDP were enrolled in the study. rTMS was used in patients for four weeks. Global functional connectivity density (gFCD) was used to assess the alterations in brain activity before and after rTMS. The MATRICS Consensus Cognitive Battery (MCCB) was used to evaluate the cognitive abilities of patients before and after rTMS. Results: Compared to the baseline, cognitive improvements were detected in patients at the end of two weeks of treatment, as determined through increased MCCB scores. The gFCD increase was observed in the frontal cortex, inferior temporal lobe, and parietal lobe. However, the MCCB scores did not increase further in the third week of treatment and declined by four weeks post-treatment. Similarly, the increased gFCD values also declined to nearly baseline values by the fourth week after treatment. Conclusions: High frequency rTMS can improve the cognitive abilities of patients with remitted BPD rapidly; however, the beneficial effects are short-lived and begin to disappear by three weeks after treatment. The brain activity alterations induced by rTMS also increased initially, followed by substantial declines, suggesting that desensitization or exhaustion may play a role. Further investigations are needed to determine the optimal method for maintaining long-term cognitive improvements in patients with remitted BPD.