Characterization of vascular dementia with TMS: A systematic review and meta‐analysis

Abstract

AbstractBackgroundVascular dementia (VaD) is the second most common cause of dementia. However, the variety of lesions in different vessels make VaD heterogeneous. VaD has been studied using transcranial magnetic stimulation (TMS) in patients with multi‐infarct dementia, subcortical ischemic vascular dementia (SIVD), and with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). There is, however, some controversy about the reported impairment in cortical excitability and cortical circuits in VaD(1–5). Therefore, we reviewed systematically TMS characterization in patients with VaD.MethodWe conducted a systematic review following PRISMA guidelines. Our search strategy included terms related to VaD and TMS and was conducted in 4 databases (MEDLINE, EMBASE, Ovid and Scopus) from origin to April 2021. Two authors screened the studies in a 2‐stepwise approach. Original studies, comparing any type of VaD to healthy controls (HC) using TMS. Case reports and series were excluded. Risk of bias was assessed using QUADAS. Meta‐analyses comparing various TMS parameters between VaD and HC were conducted. Demographic data (age, sex, comorbidities, years of education, onset age, diagnosis information), subtype of vascular dementia, reference standard, and TMS parameters were extracted.ResultAfter duplicates were removed our search yielded 216 results. After applying the eligibility criteria, 26 articles were fully screened and finally 8 articles were reviewed and included in the meta‐analysis(4–11). A total of 145 patients with VaD were analyzed, and most of them had SIVD (69.65%) and CADASIL (11.72%); 140 HC were also analyzed. When compared VaD patients to HC, the mean differences of resting motor threshold (RMT) and short‐latency afferent inhibition (SAI) values were statistically significant (Fig 1‐2).ConclusionThis is the first systematic review to describe the differences of TMS parameters between patients with VaD and HC. RMT and SAI values were significantly altered in patients with VaD suggesting that both cortical excitability and cholinergic transmission are affected. These parameters could be further used to understand the impact of vascular events in neurotransmission. Furthermore, because of the difficulty of detecting vascular lesions in structural imaging studies, TMS characterization may allow a clearer diagnosis of VaD.