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Effects of low versus high frequencies of repetitive transcranial magnetic stimulation on cognitive function and cortical excitability in Alzheimer’s dementia


Ahmed, Mohamed A., Darwish, Esam S., Khedr, Eman M., El Serogy, Yasser M., Ali, Anwer M.


Journal Of Neurology, Volume: 259, No.: 1, Pages.: 83-92

Year of Publication



The aim of the study was to compare the long-term efficacy of high versus low frequency repetitive transcranial magnetic stimulation (rTMS), applied bilaterally over the dorsolateral prefrontal cortex (DLPFC), on cognitive function and cortical excitability of patients with Alzheimer’s disease (AD). Forty-five AD patients were randomly classified into three groups. The first two groups received real rTMS over the DLPFC (20 and 1 Hz, respectively) while the third group received sham stimulation. All patients received one session daily for five consecutive days. In each session, rTMS was applied first over the right DLPFC, immediately followed by rTMS over the left DLPFC. Mini Mental State Examination (MMSE), Instrumental Daily Living Activity (IADL) scale and the Geriatric Depression Scale (GDS) were assessed before, after the last (fifth) session, and then followed up at 1 and 3 months. Neurophysiological evaluations included resting and active motor threshold (rMT and aMT), and the duration of transcallosal inhibition (TI) before and after the end of the treatment sessions. At base line assessment there were no significant differences between groups in any of the rating scales. The high frequency rTMS group improved significantly more than the low frequency and sham groups in all rating scales (MMSE, IADL, and GDS) and at all time points after treatment. Measures of cortical excitability immediately after the last treatment session showed that treatment with 20 Hz rTMS reduced TI duration. These results confirm that five daily sessions of high frequency rTMS over the left and then the right DLPFC improves cognitive function in patients with mild to moderate degree of AD. This improvement was maintained for 3 months. High frequency rTMS may be a useful addition to therapy for the treatment of AD.;

Bibtex Citation

@article{Ahmed_2011, doi = {10.1007/s00415-011-6128-4}, url = {}, year = 2011, month = {jun}, publisher = {Springer Science $mathplus$ Business Media}, volume = {259}, number = {1}, pages = {83--92}, author = {Mohamed A. Ahmed and Esam S. Darwish and Eman M. Khedr and Yasser M. El serogy and Anwer M. Ali}, title = {Effects of low versus high frequencies of repetitive transcranial magnetic stimulation on cognitive function and cortical excitability in Alzheimer's dementia}, journal = {Journal of Neurology} }


aged, aged, 80 and over, alzheimer disease, cerebral cortex, cognition, corpus callosum, data interpretation statistical, dopaminergic neurons, educational status, electroencephalography, electromyography, female, geriatric assessment, humans, magnetic, magnetic resonance imaging, male, methods, middle aged, motor cortex, neuropsychological tests, physiology, physiopathology, psychology, stimulation, synaptic transmission, therapy, transcranial, transcranial magnetic stimulation

Countries of Study


Types of Dementia

Alzheimer’s Disease

Types of Study

Randomised Controlled Trial

Type of Outcomes

ADLs/IADLs, Cognition, Depression and Anxiety

Type of Interventions

Non-pharmacological Treatment

Non-Pharmaceutical Interventions