Background: Very few comparative studies have focused on the differences in the causes of ischemic stroke between young adults and non-young adults. This study was performed to determine what causes of ischemic stroke are more important in young adults than in non-young adults using a large-scale multicenter hospital-based stroke registry in Fukuoka, Japan.
Methods and results: We investigated data on 15,860 consecutive patients aged ≥18 years with acute ischemic stroke (mean age: 73.5 ± 12.4 years, 58.2% men) who were hospitalized between 2007 and 2019. In total, 779 patients were categorized as young adults (≤50 years of age). Although vascular risk factors, including hypertension, diabetes mellitus, and dyslipidemia, were less frequent in young adults than in non-young adults, the prevalence of diabetes mellitus and dyslipidemia in young adults aged >40 years were comparable to those of non-young adults. Lifestyle-related risk factors such as smoking, drinking, and obesity were more frequent in young adults than in non-young adults. As young adults became older, the proportions of cardioembolism and stroke of other determined etiologies decreased, but those of large-artery atherosclerosis and small-vessel occlusion increased. Some embolic sources (high-risk sources: arterial myxoma, dilated cardiomyopathy, and intracardiac thrombus; medium-risk sources: atrial septal defect, nonbacterial thrombotic endocarditis, patent foramen ovale, and left ventricular hypokinesis) and uncommon causes (vascular diseases: reversible cerebral vasoconstriction syndrome, moyamoya disease, other vascular causes, arterial dissection, and cerebral venous thrombosis; hematologic diseases: antiphospholipid syndrome and protein S deficiency) were more prevalent in young adults than in non-young adults, and these trends decreased with age.
Conclusions: Certain embolic sources and uncommon causes may be etiologically important causes of ischemic stroke in young adults. However, the contribution of conventional vascular risk factors and lifestyle-related risk factors is not negligible with advancing age, even in young adults.