By Dr. Liji Thomas, MD Reviewed by Lauren Hardaker Mar 11 2026 A massive analysis of more than 100 million participants reveals that several commonly used illicit substances may raise the risk of stroke, with genetic evidence strengthening the case that substance use disorders could play a causal role. Study: Does illicit drug use increase stroke risk? A systematic review, meta-analyses, and Mendelian randomization analysis . Image credit: cunaplus/Shutterstock.com Multiple epidemiological