Abstract
Background: Recent studies have indicated that repetitive transcranial
magnetic stimulation (rTMS) could improve cognitive function in people with Alzheimer’s
disease (AD). Yet the results are inconclusive.
Objective: This meta-analysis aimed to evaluate recent rTMS studies conducted
in mild to moderate AD patients.
Methods: PubMed, Embase, MEDLINE databases and Science Direct were searched
for studies of rTMS treatment on AD patients with cognitive impairment published before
February 2015. The relevant primary outcomes of cognition were extracted from those
included studies. A crude standardized mean difference (SMD) with 95% confidence interval
(CI) was calculated by using random effect models.
Results: Seven studies with a total of 94 mild to moderate AD patients were
included in this meta-analysis. A significant overall rTMS treatment effect on cognition
was found for all AD patients (p = 0.0008, SMD = 1.00, 95%
CI = 0.41–1.58). Stratification analysis showed that this effect is stimulation frequency-
and hemisphere-dependent. High frequency stimulation (>1.0 Hz) (p <
0.05) but not low frequency stimulation (≤1.0 Hz) (p > 0.05) was
significantly effective in improving the cognition of AD patients. Further, rTMS
stimulation on right dorsolateral prefrontal cortex (DLPFC) and bilateral DLPFC
(p < 0.05), but not on the left DLPFC (p >
0.05) was significantly effective in improving cognitive function of AD patients. A
significant effect was observed in the rTMS subgroup (p < 0.05),
rather than in the rTMS+drug subgroup (p > 0.05).
Conclusion: This meta-analysis supports that high frequency rTMS stimulation
on right- or bilateral-DLPFC has significant therapeutic effect on cognitive function in
patients with mild to moderate AD. Due to small number of studies included, more
well-controlled rTMS studies should be evaluated in AD patients in the future.
