Long-Term Cannabis Use Leaves Marks on DNA, Dunedin Study Finds | Research

The takeaway

The decades-long Dunedin birth cohort study found that long-term cannabis users had distinct DNA methylation patterns compared to non-users.

Genetics researchers, long-term cannabis users, epigenetics enthusiasts

Decades-long Dunedin Study links cannabis use to DNA methylation changes

What the researchers found

Analysis of the Dunedin Multidisciplinary Health and Development Study revealed that decades of cannabis use was associated with specific DNA methylation changes, a type of epigenetic modification that can alter gene expression without changing the DNA sequence itself.

Why it matters

Epigenetic changes represent a biological mechanism through which cannabis exposure could have lasting effects on health, potentially affecting gene regulation in ways that persist beyond active use.

The numbers in context

Drawn from the Dunedin Study, a birth cohort followed for decades; specific methylation sites and effect sizes in full text.

How the study worked

Longitudinal birth cohort study (Dunedin Study) following participants from birth, with DNA methylation profiling conducted to compare long-term cannabis users with non-users.

What this study cannot tell us

Observational design cannot confirm cannabis directly caused the methylation changes. Other lifestyle factors correlated with cannabis use could contribute. Functional significance of identified methylation changes needs further study.

How to read the evidence

One of the world's most rigorous longitudinal birth cohort studies, though observational design limits causal claims.

When this study was published

2025 analysis from the ongoing Dunedin Study, which began tracking participants at birth.

The bigger picture

Epigenetics is an emerging frontier in understanding how environmental exposures, including drug use, leave lasting biological imprints. These findings add cannabis to the list of substances with documented epigenetic signatures.

Questions still open

Do these methylation changes have clinical consequences? Are they reversible after stopping cannabis use? Could they be transmitted to offspring?

Common questions

Does cannabis change your DNA?

Not the DNA sequence itself, but this study found long-term cannabis use was associated with changes in DNA methylation, an epigenetic modification that affects how genes are expressed.

What is the Dunedin Study?

A world-renowned birth cohort study from New Zealand that has followed over 1,000 people from birth through middle age, providing some of the strongest longitudinal health data available.

Read the original research

DNA methylation profiles of long-term cannabis users in midlife: a comprehensive evaluation of published cannabis-associated methylation markers in a representative cohort.

Molecular psychiatry, 30(10), 4576-4590

View on PubMed ↗Publisher’s paper ↗

Citation

Meier, Madeline H; Sugden, Karen; Moffitt, Terrie E; Williams, Benjamin S; Bourassa, Kyle J; Houts, Renate; Ramrakha, Sandhya; Theodore, Reremoana; Caspi, Avshalom. (2025). DNA methylation profiles of long-term cannabis users in midlife: a comprehensive evaluation of published cannabis-associated methylation markers in a representative cohort.. Molecular psychiatry, 30(10), 4576-4590. https://doi.org/10.1038/s41380-025-03042-9