Introduction: Previous epidemiological studies have found an increased risk for ischemic stroke in patients with migraine; however, the evidence for a causal relationship between migraine and ischemic stroke is scarce. This study aims to explore the potential causal relationship between migraine and ischemic stroke and its subtypes [including large artery stroke (LAS), small vessel stroke (SVS), and cardioembolic stroke (CES)]. Methods: We used data on genetic variants associated with migraine identified from a genome-wide association study (GWAS) metaanalysis among 889,018 European ancestries. Summary data for ischemic stroke and its subtypes were obtained from the MEGASTROKE consortium including up to 438,847 participants. We performed two-sample Mendelian randomization (MR) analyses using the inversevariance-weighted method as the primary approach. The MR-Egger, weighted median, simple median, simple mode, and weighted mode methods were also conducted as sensitivity analyses to determine the robustness of our results. Results: We failed to detect statistically significant associations between migraine and ischemic stroke (OR, 0.935; 95% CI 0.851-1.027; P = 0.159) and its subtypes (LAS: OR, 0.818; 95% CI 0.692-0.967; P = 0.018) (SVS: OR, 0.935; 95% CI 0.781-1.119; P = 0.460) (CES: OR, 1.015; 95% CI 0.867-1.189; P = 0.850). The results were consistent with the sensitivity analyses. Conclusions: By conducting a series of causal inference approaches, this study supports no causal effect of migraine on ischemic stroke and its subtypes.

Background and purposeThis study aimed to investigate the association of metabolic syndrome (MetS) with both intracranial atherosclerotic stenosis (ICAS) and imaging markers of cerebral small vessel disease (CSVD) in a community-based sample.MethodsThis study included 943 participants (aged 55.6±9.2 years, 36.1% male) from the community-based Shunyi cohort study. MetS was defined according to the joint interim criteria and quantified by the MetS severity Z-score. ICAS was evaluated by brain magnetic resonance angiography. The MRI markers of CSVD, including white matter hyperintensities (WMHs), lacunes, cerebral microbleeds (CMBs) and enlarged perivascular spaces (EPVS), were assessed. Multiple regression models were used to investigate the association of MetS severity Z-score with ICAS and these CSVD markers.ResultsWe found that risk of ICAS (OR=1.75, 95% CI 1.39 to 2.21, p<0.001) increased consistently with MetS severity. MetS severity was significantly associated with higher risks of WMH volume (β=0.11, 95% CI 0.01 to 0.20, p=0.02) and lacunes (OR=1.28, 95% CI 1.03 to 1.59, p=0.03) but not the presence of CMBs (OR=0.93, 95% CI 0.74 to 1.16, p=0.51) and PVS severity (EPVS in basal ganglia: OR=0.96, 95% CI 0.84 to 1.09, p=0.51 and EPVS in white matter: OR=1.09, 95% CI 0.96 to 1.23, p=0.21).ConclusionsOur findings suggest that WMH and lacunes share risk factors with atherosclerosis of the cerebral artery, whereas the impact of glucose and lipid metabolic disorder to CMB or EPVS might be weak.

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