Department of Neurology, Christian Doppler Clinic, Paracelsus Medical University, Salzburg, Austria. raffaele.nardone @ asbmeran-o.it
Dement Geriatr Cogn Disord. 2011;32(1):18-25. doi: 10.1159/000330016. Epub 2011 Aug 4.
Central cholinergic circuits of human brain can be tested non-invasively by coupling electrical peripheral stimulation with transcranial magnetic stimulation (TMS) of the motor cortex. The short-latency afferent inhibition (SAI) is reduced in cholinergic forms of dementia, such as Alzheimer disease (AD) and dementia with Lewy bodies, while it is normal in non-cholinergic forms of dementia, such as frontotemporal dementia. This finding suggests that this method can be used as a non-invasive additional tool for discriminating between cholinergic and non-cholinergic forms of dementia. Interestingly, SAI was also found to be significantly smaller in early AD patients. Identification of SAI abnormalities that occur early in the course of AD will allow earlier diagnosis 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 dysfunction. It has recently been demonstrated that brain microbleeds 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.
人脑的中枢胆碱能回路可以通过将外周电刺激与运动皮层的经颅磁刺激（TMS）耦合来进行非侵入性测试。在胆碱能痴呆形式中，如阿尔茨海默病（AD）和路易体痴呆，短潜伏期传入抑制（SAI）降低，而在非胆碱能痴呆形式中，如额颞叶痴呆，SAI 是正常的。这一发现表明，该方法可作为一种非侵入性的附加工具，用于区分胆碱能和非胆碱能痴呆形式。有趣的是，在早期 AD 患者中也发现 SAI 明显更小。识别 AD 病程早期出现的 SAI 异常将允许更早地进行诊断和使用胆碱能药物进行治疗。在血管性痴呆患者中，SAI 反应差异很大；异常 SAI 的患者数量可能反映了具有明显胆碱能功能障碍的受试者的百分比。最近已经证明，脑微出血对 SAI 的影响独立于相关白质变化和缺血性中风的程度。由于乙酰胆碱酯酶抑制剂可以增加 SAI，因此 TMS 可能有助于确定适合长期使用胆碱能药物治疗的患者。
