Chronic Cannabis Use in Teens Linked to DNA Changes That May Affect Verbal Memory | Research

The takeaway

In a small study of 18 adolescents, chronic cannabis use was associated with changes at six DNA methylation sites that statistically mediated the link between cannabis use and lower verbal learning scores.

People interested in the biological mechanisms behind cannabis effects on adolescent cognition

6 DNA methylation sites identified

What the researchers found

Six CpG methylation sites showed reduced methylation associated with the extent of chronic cannabis use. All six sites mediated the relationship between cannabis use and impaired verbal free recall performance. The affected genes had been previously linked to neurodegeneration, hippocampus-dependent learning, and neurogenesis.

Why it matters

This is among the first studies to look at whether DNA methylation changes might explain how cannabis affects memory in young people. If confirmed, it would suggest cannabis does not just temporarily impair cognition but may alter gene expression in ways relevant to brain function.

The numbers in context

18 adolescents total (9 cannabis users, 9 controls); 6 CpG sites with reduced methylation; all 6 mediated the effect on verbal learning free recall; cannabis users abstinent at least 24 hours before testing

How the study worked

Exploratory whole-genome methylation study of 18 adolescents (9 psychiatric outpatients with chronic cannabis use, 9 matched controls without). Groups matched for age, gender, and psychiatric disorders. Cannabis users were abstinent at least 24 hours before cognitive testing. Blood samples analyzed for CpG methylation via principal component analysis and mediation analyses.

What this study cannot tell us

Very small sample of 18 participants severely limits statistical power and generalizability. Cannot determine whether methylation changes are caused by cannabis use or reflect pre-existing differences. Peripheral blood methylation may not reflect brain methylation patterns.

How to read the evidence

Exploratory study with very small sample size (n=18); findings need replication in larger cohorts

When this study was published

2022 study

The bigger picture

Epigenetic changes represent a potential biological mechanism connecting cannabis use to cognitive effects. If replicated in larger samples, these methylation markers could become useful biomarkers for cannabis-related cognitive risk.

Questions still open

Do these methylation changes reverse with sustained abstinence? Are the same patterns present in adult cannabis users? Would brain tissue show similar methylation changes at these sites?

Common questions

Does cannabis permanently change DNA in teenagers?

This study found changes in DNA methylation, not DNA sequence. Methylation is a chemical modification that affects gene expression and may be reversible, though this study did not test reversibility.

How reliable are findings from 18 participants?

Findings from such a small sample are preliminary and exploratory. The authors themselves note that results must be carefully interpreted and replication studies are needed.

Read the original research

DNA methylation changes associated with cannabis use and verbal learning performance in adolescents: an exploratory whole genome methylation study.

Translational psychiatry, 12(1), 317

View on PubMed ↗Publisher’s paper ↗

Citation

Wiedmann, Melina; Kuitunen-Paul, Sören; Basedow, Lukas Andreas; Wolff, Max; DiDonato, Nataliya; Franzen, Julia; Wagner, Wolfgang; Roessner, Veit; Golub, Yulia. (2022). DNA methylation changes associated with cannabis use and verbal learning performance in adolescents: an exploratory whole genome methylation study.. Translational psychiatry, 12(1), 317. https://doi.org/10.1038/s41398-022-02025-6