Time-of-day Pattern of Stroke Onset in Women: Interim Analysis Linking Menopausal Status and Autoimmune Comorbidity to Circadian Patterns
Parisa Heidari1, Shayan Sadegh2
1Hackensack University Medical Center, 2Hackensack Meridian School of Medicine
Objective:
To characterize timing of ischemic stroke and TIA in women and explore associations with initial severity, autoimmune status, and menopausal proxy metrics.
Background:
Circadian variation in stroke onset is well established, with ischemic events most frequent in the morning. Most prior studies included predominantly men or mixed cohorts, limiting insight into sex-specific mechanisms. Hormonal transitions such as menopause, and autoimmune conditions that disproportionately affect women, may alter circadian regulation, vascular reactivity, and hemostasis, influencing stroke timing and severity. Identifying high-risk windows in women could guide tailored prevention strategies
Design/Methods:
Two reviewer-curated datasets (2019–2025) were merged and limited to women. Diagnoses were identified via ICD-10 codes (I63.* ischemic stroke; G45.* TIA). Time of day was categorized into four 6-hour bins (00:00–05:59; 06:00–11:59; 12:00–17:59; 18:00–23:59). NIHSS at arrival defined initial severity. Autoimmune positivity was defined as a documented autoimmune condition or positive laboratory tests around the time of stroke. Menopausal status was proxied by age ≥50 years.
Results:
Among 435 encounters, 227 were women; 79 had ischemic stroke or TIA. Peak 6-hour window was 12:00–17:59 (n=32). NIHSS mean was 5.3, median 2.0 (n=210). Autoimmune positivity occurred in 30/227 (13.2%) overall, 12/79 (15.2%) with stroke/TIA. Using the menopause proxy, 188/227 (82.8%) were ≥50 years; 73/188 (38.8%) had stroke/TIA. Women <50 years (n=6) had events across all time bins without a dominant peak; median NIHSS 2.5 (IQR 2.0–7.5). Women ≥50 years (n=73) had 42.5% presenting 12:00–17:59; median NIHSS 4.0 (IQR 2.0–10.0).
Conclusions:
Stroke/TIA in women, particularly ≥50, tends to cluster in the afternoon, with older women showing modestly higher NIHSS. Autoimmune positivity was 13–15%. Findings suggest circadian, hormonal, and immune modulation of stroke onset. The study is ongoing; this interim analysis precedes cohort expansion (2019–2025)
Disclaimer: Abstracts were not reviewed by Neurology® and do not reflect the views of Neurology® editors or staff.