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CHRISTCHURCH, New Zealand — As cannabis use continues to rise, a new study is warning about its effects on children still in the womb. International researchers have discovered a connection between pregnant women exposing their unborn children and changes in DNA methylation — a process that can influence gene activity — in genes crucial for brain development. These changes persisted into childhood, adolescence, and even adulthood.
The study, published in Molecular Psychiatry, analyzed data from two long-term studies: one in the United Kingdom following children from birth to age 17, and another in New Zealand tracking individuals into their late 20s. By examining DNA samples at different ages, the researchers found consistent patterns of altered gene activity in those exposed to cannabis prenatally.
“We know cannabis use during pregnancy is associated with childhood and adolescent brain development and cognitive function,” says Dr. Amy Osborne, a senior lecturer at the University of Canterbury, in a media release. “However, previous studies haven’t been able to prove that cannabis exposure has specifically caused the adverse effects on neurodevelopment that have been observed.”
“In a world-first, we identified a significant number of molecular changes in genes involved in neurodevelopment and neurodevelopmental disease, across the life course. This is a key finding because it suggests there is a molecular link between prenatal cannabis exposure and impacts on the genes involved in neurodevelopment.”
Some of the affected genes play important roles in brain development and function. For example, one gene called TUBB2B is involved in the formation of the brain’s cortex, while another called LZTS2 has been linked to depression. The researchers also found changes in genes associated with learning, memory, and various neurodevelopmental disorders.
Importantly, the study found that these genetic changes were enriched in pathways related to brain development, neurotransmission, and neuronal structure. This means that the alterations weren’t random but concentrated in areas crucial for how the brain forms and functions.
“Cannabis is now the most commonly used drug, excluding alcohol and tobacco, among pregnant women in the United States and the frequency has been rising since the COVID-19 pandemic,” Dr. Osborne notes.
The findings add weight to growing concerns about cannabis use during pregnancy. With more states legalizing cannabis and public perception of its risks decreasing, understanding its potential impact on fetal development is more critical than ever.
However, it’s important to note that this study doesn’t prove that prenatal cannabis exposure directly causes neurodevelopmental problems. Instead, it provides evidence of a biological mechanism that might explain the link between cannabis exposure and developmental issues observed in other studies.
“We hope our research will inspire further investigation with larger cohorts and there will soon be clearer advice to pregnant women about the impact of cannabis use. Otherwise, the potential risk to children remains, and will likely grow,” Dr. Osborne concludes.
The research also highlights the complexity of studying prenatal exposures to all sorts of chemicals. Many people who use cannabis also use tobacco, making it challenging to separate the effects of each substance during pregnancy. The researchers attempted to account for this by controlling for tobacco exposure in their analysis.
While the study’s findings are intriguing, the authors emphasize the need for larger studies to confirm and expand upon these results. They hope their work will spark more research into how prenatal cannabis exposure affects brain development and potentially influences long-term cognitive and behavioral outcomes.
Paper Summary
Methodology
The researchers used a technique called epigenome-wide association studies (EWAS) to look at DNA methylation patterns. DNA methylation is a process that can turn genes on or off without changing the DNA sequence itself. They examined DNA samples from blood at different ages: at birth (from cord blood), at 7 years-old, 15-17 years-old, and around 27 years-old. They compared the methylation patterns in individuals exposed to cannabis prenatally to those who were not exposed, controlling for factors like tobacco exposure and sex.
Key Results
The study found hundreds of sites in the genome where DNA methylation was different in individuals exposed to cannabis prenatally. These differences were seen at all age points examined. Many of the affected genes are known to be involved in brain development or have been linked to neurodevelopmental disorders. The researchers also found that the affected genes were clustered in biological pathways related to brain development and function.
Study Limitations
The study had a relatively small sample size, particularly for individuals exposed to cannabis prenatally. This limits the strength of the conclusions that can be drawn. Additionally, it’s challenging to completely separate the effects of cannabis from other factors like tobacco use or socioeconomic status. The study also relied on self-reported cannabis use during pregnancy, which may not always be accurate.
Discussion & Takeaways
The study provides evidence for a biological mechanism that could explain how prenatal cannabis exposure might affect brain development. It suggests that these effects could persist throughout life, not just during infancy. However, the authors stress that more research is needed to confirm these findings and to understand how these genetic changes might translate into developmental outcomes. The study doesn’t prove that prenatal cannabis exposure causes developmental problems, but it does provide a compelling reason for further investigation.
Funding & Disclosures
The study was funded through a Major Project Grant from the Canterbury Medical Research Foundation. Study author Jack Satsangi is the director of the UK Inflammatory Bowel Disease Registry. The other researchers declare no biomedical financial interests or potential conflicts of interest.
Many women use cannabis to control nausea while pregnant. But the potential for brain development problems makes this risky. Any herb or drug taken during pregnancy can pose a threat to the fetus. For safety, you may want to have weed proven safe for the fetus before using it while pregnant, and not use it hoping it won’t be proven a hazard to your child years from now. Given that cannabis is a multi-billion dollar industry, like tobacco or alcohol, don’t expect honest science on this issue. Too much money for honesty.