Legal alcohol and tobacco use can increase illicit drug use

The use of legal drugs (tobacco and alcohol) can lead to the use of cannabis, a new study conducted by the University of Bristol and published in the journal Addiction found. The study also found evidence that cannabis use can lead to smoking initiation and that opioid addiction could lead to increased alcohol use. In addition, there could be shared risk factors that influence the use of multiple substances.

Legal use of alcohol and tobacco can directly increase the level of illicit drug use. However, the relationships are complex. Use of one drug appears to increase use of another, but people may also have underlying risk factors that increase their chances of using both alcohol, tobacco and drugs. illegal. “

Dr Zoe Reed, study co-author and Senior Research Associate, Tobacco and Alcohol Research Group, Bristol’s School of Psychological Science

The study found evidence of a possible bridging effect between 1) tobacco use and subsequent alcohol and cannabis use, 2) cannabis use and subsequent tobacco use, and 3) addiction opioids and subsequent alcohol consumption. It is possible that there are two-way relationships – for example between tobacco and cannabis use – where cause and effect work in both directions.

However, since tobacco and alcohol use usually begins before other drug use, it is also possible that there are shared risk factors – perhaps a common genetic predisposition to substance use – underlying these relationships. Further examination of these specific relationships is needed to determine the exact mechanisms behind these possible gateway effects.

Hazel Cheeseman, Deputy CEO of Action on Smoking and Health, commenting on the implications of the studies, said:

“Tobacco and alcohol cause enormous harm to society and these results indicate that they can also increase the use of other drugs. Governments tend to take distinct approaches to reducing the harm from legal and illegal drugs, but the long-promised addictions strategy looks at the overlap between addictions and be more integrated. “

Many studies that have sought to understand the relationship between the use of different drugs rely on observed associations. The problem with trusting the observed associations is that both types of drug use (legal and illegal) can be caused by a common underlying risk factor, such as impulsivity, and it is difficult to determine whether the relationships are causal. To avoid this problem, the research team used a statistical approach called Mendelian randomization.

Mendelian randomization uses genetics to support more solid conclusions about possible causal relationships between an exposure (a potential cause) and an outcome (a potential effect) that is less likely to be affected by a “confounder” (a third variable). which affects both exposure and outcome). In this study, the researchers used known genetic variants that predispose people to use tobacco, alcohol, cannabis, cocaine or opioids, and then examined whether there could be any causal relationships between the tobacco and alcohol and these illicit drugs.

Using genetic variants as a proxy for an exposure reduces confusion issues and makes it possible to draw more solid conclusions about whether an exposure actually causes an outcome – in this case, whether the use of a substance leads to the use of another.