Marijuana Use Linked to Lower College Completion Rates, Especially at Four-Year Schools | Research

The takeaway

In a nationally representative study of matched college students, past-year marijuana use was associated with 30% lower college completion at four-year schools, while methamphetamine and alcohol treatment predicted lower completion at two-year schools.

University health services, college counselors, education policy researchers

30% lower college completion with past-year marijuana use at four-year schools

What the researchers found

Among propensity-matched four-year college students, past-year marijuana use was associated with lower completion (IRR = 1.30, p = 0.007), with stronger effects for frequent use (>=5 times/month, IRR = 1.44). Two-year students showed different patterns: methamphetamine and alcohol treatment, not marijuana, predicted lower completion.

Why it matters

This study separates effects of different substances on educational attainment at different institution types, finding marijuana specifically affects four-year completion but not two-year.

The numbers in context

888 two-year and 1,398 four-year matched students; past-year marijuana IRR 1.30; >=5 times/month IRR 1.44; 7-year follow-up; matched on 15 variables.

How the study worked

Propensity-matched analysis from Add Health. 888 two-year and 1,398 four-year college students matched on 15 measures. Educational attainment measured 7 years later.

What this study cannot tell us

Observational design cannot prove marijuana caused lower completion. Propensity matching reduces but does not eliminate confounding.

How to read the evidence

Large nationally representative cohort with propensity matching and 7-year follow-up, limited by observational design.

When this study was published

2024 publication using Add Health data

The bigger picture

As marijuana legalization expands, the dose-response pattern and different patterns at two-year versus four-year schools suggest tailored intervention approaches may be needed.

Questions still open

Why does marijuana appear to affect four-year but not two-year college completion?
Would targeted academic functioning interventions improve completion rates?

Common questions

Does marijuana affect college graduation rates?

Past-year marijuana use was associated with 30% lower completion at four-year colleges, increasing to 44% for students using 5+ times per month. Marijuana did not significantly predict completion at two-year colleges.

Is the effect of marijuana on college different from alcohol?

Yes. At four-year schools, marijuana predicted lower completion while alcohol did not. At two-year schools, alcohol treatment history predicted lower completion but marijuana did not.

Read the original research

Substance Use and College Completion Among Two-Year and Four-Year College Students From a Nationally Representative Longitudinal Study.

Cureus, 16(5), e61297

View on PubMed ↗Publisher’s paper ↗

Citation

Rosenbaum, Janet E. (2024). Substance Use and College Completion Among Two-Year and Four-Year College Students From a Nationally Representative Longitudinal Study.. Cureus, 16(5), e61297. https://doi.org/10.7759/cureus.61297