QUANTITATIVE CHANGES IN COGNITIVE FLEXIBILITY INDUCED BY TRANSCRANIAL MAGNETIC STIMULATION IN DEPRESSION: A PRELIMINARY REPORT
Authors: Watanabe *Anri , Narumoto Jin 
Published: February 2025

Abstract

Background
Cognitive behavioral therapy (CBT) and pharmacotherapy have been shown to be effective for depression, but inflexible cognition makes it difficult to introduce these therapies, and even when treated with CBT, cognitive change is not achieved, and medication adherence is likely to be inadequate. This is thought to be related to a lack of cognitive flexibility, which is defined as the ability to rapidly change behavior in the face of changing circumstances. On the other hand, transcranial magnetic stimulation (TMS) has not only the efficacy for depression but also the potential to improve cognitive flexibility. By clarifying the effects of TMS on cognitive flexibility, we can develop new treatment and methods to maximize the effectiveness of CBT and pharmacotherapy.

Aims & Objectives
The main objective of this study is to clarify the impact of TMS on cognitive flexibility by comparing the results of psychological tests before and after TMS.

Method
The subjects were patients with major depressive disorder who had undergone TMS at University Hospital, Kyoto Prefectural University of Medicine. The Japanese version of the cognitive flexibility scale (CFS-J) was used as a quantitative measure of cognitive flexibility and the primary outcome was the change in CFS-J scores before and after the TMS course. Other information such as age, gender, and changes in Hamilton Rating Scale for Depression (HAM-D) were also collected. They received TMS treatments for 1 session per day and 5 days per week for a total of 30 sessions based on protocols covered by insurance in Japan. Each treatment included 3000 pulses at 10 Hz and 100–120% motor threshold, and the stimulation lasted for 4 seconds, followed by a 26-34 seconds stimulation interval. To evaluate the change in scores from baseline to the end of the TMS course paired samples t-tests were performed for the CFS-J. The study was reviewed and approved by the Institutional Review Board of the Kyoto Prefectural University of Medicine.

Results
Data were collected from 3 subjects (2 males and 1 female), with a mean age of 71 years. The mean CFS-J before TMS was 40.3 and after TMS was 51.3; CFS-J scores were improved with TMS (p = 0.069). Meanwhile, the mean pre-TMS HAM-D score was 17.7 and post-TMS was 10; HAM-D scores were improved (p = 0.063).

Discussion & Conclusion
This study quantitatively demonstrated that TMS enhanced cognitive flexibility, but did not show statistically significant differences. Due to the small sample size of this preliminary report, we will continue to accumulate data and examine changes in the CFS-J before and after TMS, as well as the relationship between various factors and cognitive flexibility, including the rate of improvement in depressive symptoms. Cognitive flexibility plays a significant role in depression, as studies of patients with treatment-resistant depression have reported that cognitive flexibility is a predictor of treatment response. Since cognitive flexibility contributes to the promotion of treatment efficacy, attention should be paid not only to the improvement of depressive symptoms with TMS, but also to its effect on cognitive flexibility.