Transcranial magnetic stimulation in Alzheimer disease: motor cortex excitability and cognitive severity

Motor cortex excitability in Alzheimer's disease and in subcortical ischemic vascular dementia

“…These findings in AD patients confirm and support the previous reports [1,11,15,17]. The hyperexcitability is not due to aging, and in fact it has been shown as an increment of MT in elderly adults when compared with young subjects [14,20].…”

“…It represents a valid tool to study the motor cortex excitability through the evaluation of the motor threshold (MT). In the last years, MT has been investigated in AD patients [1,15,17] but there are no reports available on motor cortex excitability in VaD patients.…”

“…It represents a valid tool to study the motor cortex excitability through the evaluation of the motor threshold (MT). In the last years, MT has been investigated in AD patients [1,15,17] but there are no reports available on motor cortex excitability in VaD patients.In the present work, motor cortex excitability changes were studied in AD and SIVD patients to assess the electrophysiological differentiation and the eventual usefulness of MT for a better clinical evaluation of these two types of dementia.Twenty SIVD patients (eight men, 12 women, age range 48-84 years, mean age 71.8^9.37 years), 20 AD patients (seven men, 13 women, age range 55-82 years, mean age 72.2^7.53 years) and 20 neurologically and cognitively intact subjects (eight men and 12 women, age range 52-80 years, mean age 68.55^7.96 years) were studied. The study was approved by the local ethics committee and informed consent was obtained from all patients (or from close relatives) and control subjects.…”

Transcranial magnetic stimulation-evoked EEG/cortical potentials in physiological and pathological aging

“…This finding confirms and extends the results of a previous pilot study, in which the primary motor cortex was stimulated [20]; in this case, the comparison between patients with Alzheimer's disease and age-matched controls showed a reduction of global EEG response to TMS between 30 and 50 ms, and a lower current density in the stimulated cortex at approximately 30 ms after TMS pulses. Previous studies, using TMS-evoked motor potentials (MEPs) have found a reduced motor threshold in patients with Alzheimer's disease compared with healthy controls, and have interpreted this result as an increased excitability of the corticospinal motor system [21][22][23]. These findings have been ascribed to an impairment of inhibitory GABAergic activity; alternatively, muscle tone, which has a facilitation effect on MEPs [24] and which was found to be increased in Alzheimer's disease [25], may play a role.…”

A Review of Transcranial Magnetic Stimulation in Vascular Dementia

“…Many TMS studies have examined motor cortex excitability and motor cortical output after acute stroke, in the poststroke recovery and in brain reorganization, providing relevant data for their prognosis and therapeutic approach [47,48,49,50,51,52,53]. TMS has also been applied to study motor cortex changes in patients with cognitive disorders such as AD [54,55,56,57,58,59],frontotemporal dementia [59]and dementia with Lewy bodies [60] . …”