The link between alcohol and depression has long been known, but there has been much disagreement about whether alcoholism causes depression or vice-versa. The relationship between the two is alluded to by several facts, including that around one third of people who suffer from major depression also have a problem with alcoholism and that teens or children who suffer from depression are more likely to develop an alcohol problem. Because of this existing body of research, the finding from a new piece of genetic research into the links between alcohol and depression—that there is no intrinsic link between the two—is a particularly surprising one. Finding out more about the research and why the link has been previously assumed helps you understand the role of alcoholism and addiction in depression.
The Assumption
Whether it’s the stereotypical drinker who tries to “drown his sorrows” or the chronic alcoholic who constantly appears to be down about something, most of us have made the assumption that there is some kind of link. There have been numerous pieces of research previously conducted on the topic, but the results haven’t always been clear. The assumption is that the effects of alcohol on the brain mean that a particularly heavy period of drinking can lead to depression, and that the other impacts of excessive drinking—problems in your personal and professional life—can obviously lead to depression in a less direct fashion. The condition known as “substance induced mood disorder” is a diagnostic relic of this supposed effect—where the consumption of substances has directly caused emotional issues. However, there has been a long-standing uncertainty as to whether alcohol consumption directly leads to depression, or whether depressed people are more likely to drink alcohol.
The Study
Researchers from the University of Western Australia set out to answer this question by looking at a gene closely related to alcoholism and looking at the psychological histories of people possessing it. The gene that was chosen – ADH1B – has a variation that can drastically reduce the individual’s ability to metabolize alcohol; this means that people with the gene can’t drink very much and are consequently less likely to develop a problem with alcohol. The theory behind the study is that if alcoholism causes depression, the people with this gene (who are much less likely to have an alcohol problem) will be less likely to have depression than those with the ordinary variant. They analyzed data from another study, which focused on the health of elderly men, and found nearly 3,900 elderly male participants for the study. Performing an analysis of the already-collected data, they were able to look at the triangular link between the specific gene, alcoholism and depression. This is a particularly useful way to research the issue, because the participants were born with the gene, so any links are less likely to be influenced by social, economic or other factors that could distort the findings. The research was published in the journal Molecular Psychiatry.
What They Found
As expected, men with the specific gene were less likely to have a problem with alcohol, and drank much less. However, there was no association whatsoever found between the gene and depression. This means that the gene neither made it more or less likely that the individual would develop depression. From this, the researchers concluded that alcohol use doesn’t cause or prevent depression, calling into question recent findings that moderate drinking has some sort of protective effect for mental health.
Correlation and Causation
The research appears to show that the assumed link between alcohol use and depression was a symptom of something else. The problem is that when you conduct a “naturalistic” study (i.e., surveying people at regular intervals about alcohol use and mental health but allowing them to continue in their day to day lives) there are numerous other factors that could impact your findings. If a survey found that people who drink more than two glasses of wine per day are more likely to struggle with depression, it establishes a correlation, but correlation does not always equal causation. It could be, for example, that the heavier drinkers are responding to stress at work, which is causing their depression as opposed to the alcohol itself. The key point is that there could be a confounding variable that is producing the result and not the one you’re looking to measure. In the case of the alcohol and depression studies, it could be that a low mood causes people to self-medicate by drinking, thus giving the false impression that alcohol makes people depressed.
Conclusion: What It Doesn’t Mean
There is an inherent danger that any piece of research like this could lead people to think that drinking is fine. As an example, Time magazine went for “Drink Up, Because Booze Won’t Make You Depressed” as a headline to their story about the study. Of course, this isn’t true, because alcohol abuse is still responsible for numerous deaths every year, and it is an addictive and potentially life-destroying drug. Time elaborated later, however, quoting one of the study’s researchers, who clarified: “It doesn’t mean alcohol is entirely safe and people can consume it in whatever way they like. We know that alcohol when consumed in excess does create a lot of health problems—but what we now know is that one of those problems is not depression.”
