A systematic review and meta-analysis of rTMS effects on cognitive enhancement in mild cognitive impairment and Alzheimer's disease

• Published in: Neurobiology of aging 2020-02, Vol.86, p.1-10
• Main Authors: Chou, Ying-hui, Ton That, Viet, Sundman, Mark
• Format: Article
• Language: English
• Subjects: Alzheimer Disease - psychology; Alzheimer Disease - therapy; Alzheimer's disease; Cognition; Cognitive Dysfunction - psychology; Cognitive Dysfunction - therapy; Dorsolateral prefrontal cortex; Humans; Intervention; Memory; Mild cognitive impairment; Plasticity; Prefrontal Cortex - physiopathology; Therapy; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; Treatment
• ISSN: 0197-4580; 1558-1497; 1558-1497
• DOI: 10.1016/j.neurobiolaging.2019.08.020

Repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique, has emerged as a promising treatment for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Currently, however, the effectiveness of this therapy is unclear because of the low statistical power and heterogeneity of previous trials. The purpose of the meta-analysis was to systematically characterize the effectiveness of various combinations of rTMS parameters on different cognitive domains in patients with MCI and AD. Thirteen studies comprising 293 patients with MCI or AD were included in this analysis. Random-effects analysis revealed an overall medium-to-large effect size (0.77) favoring active rTMS over sham rTMS in the improvement of cognitive functions. Subgroup analyses revealed that (1) high-frequency rTMS over the left dorsolateral prefrontal cortex and low-frequency rTMS at the right dorsolateral prefrontal cortex significantly improved memory functions; (2) high-frequency rTMS targeting the right inferior frontal gyrus significantly enhanced executive performance; and (3) the effects of 5–30 consecutive rTMS sessions could last for 4–12 weeks. Potential mechanisms of rTMS effects on cognitive functions are discussed. •Repetitive transcranial magnetic stimulation (rTMS) is a promising tool to enhance cognitive functions in Alzheimer's disease and mild cognitive impairment.•High-frequency left dorsolateral prefrontal cortex and low-frequency right dorsolateral prefrontal cortex rTMS may improve memory function.•High-frequency right inferior frontal gyrus rTMS may enhance executive performance.•rTMS effects on cognition are documented at both acute and chronic time points.•Chronic effects of consecutive rTMS sessions reportedly persist at 12 weeks.