Genetic link between cannabis and teenage depression

A study carried out in the Netherlands indicates that there is a link between marijuana use and depression at the genetic level. Considering that a large percentage of the population is susceptible to depression, this study is further evidence of the damage that drug use can have on your mental health.

A long-term study, that took place over five years in the Netherlands and included 428 families with an average of two adolescent children each, showed that young people with the specialist variant of the serotonin gene called 5 HTT, which gave them an increased vulnerability to depression, experienced an increase in symptoms of depression after exposure to cannabis.

The message to young people is although they may consider smoking cannabis to be harmless, they should look at their family genetics. If there is any depressive illness in their family tree at all, then avoiding the drug altogether would be prudent. And the gene is more common than you might imagine, with up to two-thirds of the population carrying the variant gene that makes someone more susceptible to depression.

The research was carried out at the Behavioural Science Institute of Radboud University Nijmegen by Roy Otten, and has been published in the online version of the scientific journal, Addiction Biology, for anyone who is interested in reading the full study.

Close to 30% of all young people in the Netherlands (where cannabis is an exceptionally popular drug), admit to having used it at least once, and a good percentage of those say they have used the drug within the last month. The study shows that smoking cannabis can cause an increased risk of developing illnesses such as schizophrenia and is a known trigger for psychosis.

Cannabis use linked to depression

Young people taking cannabis also experienced a reduction in their performance at school. Whilst cannabis has often been linked to depression in the past, no scientific evidence has been able to prove the link conclusively up until this study when genetics were evaluated.

Otten says: "The effect is robust. It still remains, even if you take into account a series of other variables that could cause the effect, such as smoking behaviour, alcohol use, upbringing, personality and socio-economic status. Some people might think that young people with a disposition for depression would start smoking cannabis as a form of self-medication, and that the presence of depressive symptoms is therefore the cause of cannabis use. However, in the longer term that is definitely not the case. Although the immediate effect of cannabis may be pleasant and cause a feeling of euphoria, in the longer term, we observe that cannabis use leads to an increase in depressive symptoms in young people with this specific genotype."

This is an important finding in the long-term. There is hope that arming our young people with the knowledge that a fairly large proportion of our population will be exposing themselves to a mental illness by using cannabis, may go some way to preventing them experimenting with the drug in the first place.