Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Review Article Dement Geriatr Cogn Disord 2011;32:18–25 DOI: 10.1159/000330016 A Review of Transcranial Magnetic Stimulation in the in vivo Functional Evaluation of Central Cholinergic Circuits in Dementia Raffaele Nardone a, c Stefan Golaszewski a, b Gunther Ladurner b Frediano Tezzon c Eugen Trinka a a Department of Neurology, Christian Doppler Clinic, Paracelsus Medical University, and b Neuroscience Institute, Christian Doppler Clinic, Salzburg, Austria; c Department of Neurology, Franz Tappeiner Hospital, Merano, Italy function. It has recently been demonstrated that brain mi- crobleeds have an impact on SAI that is independent of the extent of associated white matter changes and ischemic stroke. Since SAI can be increased by acetylcholinesterase inhibitors, TMS may help in identifying the patients who would be suitable for long-term treatment with cholinergic agents. Copyright © 2011 S. Karger AG, Basel Short-Latency Afferent Inhibition Transcranial magnetic stimulation (TMS), a non-in- vasive method for the evaluation of excitatory/inhibitory characteristics of the motor cortex, allows direct investi- gation of motor cortex function [1]. By coupling periph- eral nerve stimulation with TMS of the contralateral mo- tor cortex, it is possible to recruit several neuronal circuits of the human brain [2, 3]. Afferent input can modify the excitability of the mo- tor cortex with a complex time course [4]. Delwaide and Olivier [5] reported that median nerve stimulation at the wrist suppresses motor evoked potential (MEP) evoked by TMS 18–21 ms later in relaxed hand muscles. Similar effects could be seen after stimulation of the cutaneous Key Words Transcranial magnetic stimulation  Short-latency afferent inhibition  Cholinergic circuits  Alzheimer disease  Dementia with Lewy bodies  Frontotemporal dementia  Vascular dementia Abstract Central cholinergic circuits of human brain can be test- ed non-invasively by coupling electrical peripheral stimula- tion with transcranial magnetic stimulation (TMS) of the mo- tor cortex. The short-latency afferent inhibition (SAI) is re- duced in cholinergic forms of dementia, such as Alzheimer disease (AD) and dementia with Lewy bodies, while it is nor- mal in non-cholinergic forms of dementia, such as fronto- temporal dementia. This finding suggests that this method can be used as a non-invasive additional tool for discriminat- ing between cholinergic and non-cholinergic forms of de- mentia. Interestingly, SAI was also found to be significantly smaller in early AD patients. Identification of SAI abnormali- ties that occur early in the course of AD will allow earlier di- agnosis and treatment with cholinergic drugs. In patients with vascular dementia, SAI responses varied widely; the number of patients with abnormal SAI conceivably reflects the percentage of subjects with a significant cholinergic dys- Accepted: June 6, 2011 Published online: August 4, 2011 Dr. Raffaele Nardone Department of Neurology, Franz Tappeiner Hospital Via Rossini, 5 IT–39012 Merano (Italy) Tel. +39 04 7326 4616, E-Mail raffaele.nardone  @  asbmeran-o.it © 2011 S. Karger AG, Basel 1420–8008/11/0321–0018$38.00/0 Accessible online at: www.karger.com/dem Downloaded by: Salzburger Landeskliniken 193.170.167.8 - 8/7/2013 8:16:21 AM