Department of Neurology, Christian Doppler Clinic, Paracelsus Medical University, Salzburg, Austria.
J Neural Transm (Vienna). 2012 Apr;119(4):463-71. doi: 10.1007/s00702-011-0725-3. Epub 2011 Oct 21.
Mild cognitive impairment (MCI) is considered a transitional stage between normal aging and a diagnosis of clinically probable Alzheimer disease (AD). The role of the cholinergic system in MCI is not clearly defined and needs to be further investigated. A transcranial magnetic stimulation (TMS) protocol, the short latency afferent inhibition (SAI), may give direct information about the function of some cholinergic pathways in the human motor cortex. We aimed to evaluate in the present study the relationship of SAI to the specific clinical subtypes of MCI. SAI was examined in 20 patients with amnestic MCI (10 SD, 10 MD), twenty patients with nonamnestic MCI (10 SD, 10 MD) and ten control subjects. Motor threshold, central motor conduction time, intracortical inhibition and facilitation to paired-TMS were also evaluated. Mean SAI was significantly reduced in amnestic MCI-MD patients when compared with the controls, while it was not significantly different in amnestic MCI-SD patients and in nonamnestic patients. SAI was increased after administration of a single dose of donepezil in a subgroup of four amnestic MCI-MD patients. The other TMS parameters did not differ significantly between the four MCI groups and the control group. We demonstrated that this putative marker of central cholinergic activity differs among MCI subtypes. The amnestic-MD type of MCI might be a phenotype of incipient AD. However, this hypothesis would be better addressed in a longitudinal study of individual patients. TMS studies may be useful in identifying MCI individuals in whom cholinergic degeneration is occurred and therefore at increased risk of conversion to AD.
轻度认知障碍 (MCI) 被认为是正常衰老和临床可能的阿尔茨海默病 (AD) 诊断之间的过渡阶段。胆碱能系统在 MCI 中的作用尚不清楚，需要进一步研究。一种经颅磁刺激 (TMS) 方案，即短潜伏期传入抑制 (SAI)，可以提供关于人类运动皮层中某些胆碱能通路功能的直接信息。我们旨在评估 SAI 与 MCI 的特定临床亚型之间的关系。在本研究中，我们检查了 20 名有健忘症的 MCI 患者（10 名 SD，10 名 MD）、20 名无健忘症的 MCI 患者（10 名 SD，10 名 MD）和 10 名对照组的 SAI。还评估了运动阈值、中枢运动传导时间、皮质内抑制和对配对-TMS 的易化。与对照组相比，遗忘型 MCI-MD 患者的平均 SAI 明显降低，而遗忘型 MCI-SD 患者和非遗忘型患者的 SAI 无显著差异。在四例遗忘型 MCI-MD 患者中单次给予多奈哌齐后，SAI 增加。其他 TMS 参数在四个 MCI 组和对照组之间没有显著差异。我们证明了这种中枢胆碱能活动的假定标志物在 MCI 亚型之间存在差异。遗忘型-MD 型 MCI 可能是 AD 初期的表型。然而，这种假设在对个体患者进行的纵向研究中会更好地得到证实。TMS 研究可能有助于识别发生胆碱能退化的 MCI 个体，因此他们转换为 AD 的风险增加。
