First ischemic stroke in young adults: Sex and age-related differences in stroke rates, risk factors, and etiologies.

Introduction: Sex differences in stroke incidence, vascular risk factors (VRFs), and etiologies among young adults remain underexplored, particularly regarding age-related patterns.

Patients and methods: We retrospectively analyzed young adults (18-55 years) with first-ever ischemic stroke treated at certified acute stroke units/centers between 2014 and 2022, using Swiss Stroke Registry data. Stroke rates (per 100,000 person-years), VRFs, and etiologies were assessed by age and sex.

Results: Among 3,995 stroke patients, stroke rates were similar between sexes until age 35, after which men showed a more pronounced exponential increase. This rise was particularly notable in patients with elevated BMI and ⩾2 VRFs. The proportion of patients with ⩾2 VRFs rose with age (18-35: 22%; 36-50: 48%; 51-55: 63%). While no statistically significant differences in VRF profiles were observed between men and women aged 18-35, men accumulated VRFs about five years earlier than women, leading to a higher prevalence of multiple VRFs in men aged 36-50, with the gap narrowing in the 51-55 group. Stroke etiologies shifted with age: patent foramen ovale and cervical artery dissection predominated in younger patients, while large artery atherosclerosis, small vessel disease, and strokes of undetermined etiology increased with age, with notable sex differences.

Discussion and conclusions: This study highlights sex and age differences in ischemic stroke rates, VRFs, and etiologies among adults under 55 years. After 35, stroke rates rose more sharply in men, paralleling their higher VRF burden. These findings emphasize the importance of early management of VRFs-including overweight-to mitigate stroke risk.