According to a study published online in Stroke, smoking seems to have a causal role in subarachnoid haemorrhage (SAH).

Ilari Rautalin, from the University of Helsinki, and colleagues followed 16,282 same-sex twin pairs of Finnish origin from the older Finnish Twin Cohort between 1976 and 2018.

Risk factor information was collected about smoking, hypertension, physical activity, body mass index, alcohol consumption, and education for baseline. Within-pair differences in risk factors were examined in twin pairs discordant for SAH.

The researchers identified 116 discordant and two concordant twin pairs for fatal SAH during 869,469 person-years of follow-up. Of the discordant twin pairs, 25 were monozygotic.

Smoking (occasional/current) was associated with an increased risk for SAH death compared with non-smoking (never/former) for the whole cohort (hazard ratio, 3.33).

The twin who smoked had an increased risk for fatal SAH compared with the non-smoking twin in pairwise analyses for discordant twin pairs (hazard ratio, 6.33).

Regardless of the twin pairs’ zygosity or sex, the association remained consistent.

“Smoking increased the risk of fatal SAH, also within twin pairs, and may contribute to a familial manifestation of SAH,” the authors wrote.

SOURCE: https://www.practiceupdate.com/c/106713/2/7/?elsca1=emc_enews_daily-digest&elsca2=email&elsca3=practiceupdate_neuro&elsca4=neurology&elsca5=newsletter&rid=NTU2MjE4MTIzNzES1&lid=10332481

REFERENCE: Rautalin et al: Smoking Causes Fatal Subarachnoid Hemorrhage; https://www.ahajournals.org/doi/abs/10.1161/STROKEAHA.120.031231