Marijuana use appears to be associated with subclinical atherosclerosis, but only among ever tobacco users, according to a recent study. Researchers used data (n=3,498) from the US-based Coronary Artery Risk Development in Young Adults (CARDIA) study, a cohort of black and white men and women aged 18–30 years at baseline in 1985–86, with up to 7 follow-up examinations over 25 years. They found:

• Among 3,117 participants with abdominal artery calcium (AAC) and coronary artery calcium (CAC) measurements, 2,627 (84%) reported past marijuana use and 1,536 (49%) past daily tobacco smoking.
• Compared with tobacco smokers, 46% of whom reported ≥10 pack-years of use, only 12% of marijuana users reported ≥5 marijuana-years of use and only 6% reported having used marijuana daily.
• Among those who never smoked tobacco, cumulative marijuana-years were not associated with AAC or CAC in models adjusted for demographics, cardiovascular risk factors, licit and illicit drug exposure, and depression symptoms.
• However, among ever tobacco smokers, marijuana exposure was associated with AAC and CAC.