31 May 2016
ByAppeared in BioNews 853
A research review suggests that cannabis use damages DNA, and claims that this damage can be inherited.
The analysis looked at the available evidence on tetrahydrocannabinol (THC) – one of the active ingredients in cannabis – and suggests that this damage leads to an increased risk of cancer and birth defects, which may then be passed down the generations through an epigenetic process.
'With cannabis use increasing globally in recent years, this has a concerning impact for the population. Even if a mother has never used cannabis in her life, the mutations passed on by a father's sperm can cause serious and fatal illnesses in their children. The parents may not realise that they are carrying these mutations, which can lie dormant and may only affect generations down the track, which is the most alarming aspect,' Dr Stuart Reece from the University of Western Australia, lead author on the paper, told the Mail Online.
The authors of the paper, published in Mutation Research, propose that THC could trigger chromothripsis, a recently discovered process in which a cell's DNA suffers large-scale damage but the cell does not die. Chromothripsis has been linked to some types of cancer, birth defects and other serious illnesses.
The review cites 189 articles, presenting a summary of the evidence that cannabis causes DNA damage. They go on to describe observational studies linking increased cannabis use with increased cancer risk and fetal abnormalities, which they argue could be evidence of a causal link with the DNA damage. Finally, they describe research showing that cannabis-related DNA damage can be transmitted from parent to child in both rat and human studies. Similar effects, also passed down the generations, have been seen with the use of alcohol, cocaine and opioids.
The authors claim their findings could have important implications for healthcare professionals, researchers and policymakers. However, the paper did not mention how they chose which evidence to include in their review, and there was no discussion of the strength of the evidence they included or the limitations of the research.
According to NHS Choices, 'without a clear and systematic review of the published and unpublished science, there is a risk the authors cherry-picked the evidence, consciously or unconsciously, to fit their views. Such a one-sided-argument has its place in stimulating debate, but should not be viewed on a par with a systematic review, one of the highest levels of evidence'.
It adds that while 'this type of study serves to stimulate debate and further research, it is not reliable enough to form the foundation of policy change on its own'.