Repetitive Transcranial Magnetic Stimulation (rTMS) as a Modulator of Cognitive Dysfunction in Schizophrenia: Evidence from a Nigerian Outpatient Cohort.

Background: Cognitive deficits, especially in working memory and executive functioning, are central features of schizophrenia and major contributors to poor functional outcomes. Repetitive Transcranial Magnetic Stimulation (rTMS) has gained attention as a potential adjunctive intervention for these impairments. The study assessed the impact of rTMS on working memory and executive function in patients with schizophrenia attending Ahmadu Bello University Teaching Hospital (ABUTH), Shika-Zaria, Nigeria. Methodology: A randomized, double-blind, sham-controlled trial was conducted with 250 patients diagnosed with schizophrenia. Participants were allocated to active rTMS (n = 125) or sham rTMS (n = 125). Cognitive performance was measured at baseline and after intervention using the Working Memory Index (WMI) of the WAIS-IV and the Wisconsin Card Sorting Test (WCST). Results: A total of 238 participants (95.2%) completed the study (active rTMS = 120; sham = 118). The active rTMS group showed statistically significant improvements in working memory (mean change = +7.8; p < 0.001; Cohen's d = 0.52) and executive function (mean gain in WCST categories = +2.1; p < 0.001; Cohen's d = 0.49) compared to sham. Clinically, 45% of those receiving rTMS shifted from impaired to low-average cognitive performance, versus 9.3% in the sham group. Conclusion: rTMS produced moderate but meaningful improvements in working memory and executive function, underscoring its potential as an adjunctive therapy for schizophrenia. These findings suggest rTMS could enhance functional outcomes, particularly in resource-constrained settings.