Neurophysiological biomarkers using transcranial magnetic stimulation in Alzheimer’s disease and mild cognitive impairment: A systematic review and meta-analysis

•TMS combined with EMG permits the generation of key neurophysiological indices in the cortex.•AD patients had increased motor cortical excitability and decreased cholinergic and GABAergic functions compared with HC.•MCI patients had increased motor cortical excitability and decreased cholinergic function compared with HC.•TMS neurophysiology are useful measure to understand the pathophysiology of AD and MCI.