Does Gambling Disorder Run in Families?

It would probably surprise most people to learn that pathological gambling runs in families and probably has a heritable component. Yet, that’s exactly what colleagues and I found in our recently completed family study of DSM-IV pathological gambling. We compared the first-degree relatives of people with pathological gambling with the relatives of control subjects. (First-degree relatives are those who share 50% of their genes with the subject in question.) In fact, relatives of people with pathological gambling were over 8 times more likely to have a gambling disorder (the term now used in DSM-5 to replace “pathological gambling”) than the relatives of controls. This magnitude of difference is on the order of what might be seen for the major mental disorders and substance use disorders.

While the fact that an illness runs in families strongly suggests that its transmission is genetic, illnesses can run in families for nongenetic reasons, too—for example, a behavior modeled by parents can be copied by offspring. That said, this is a finding of major significance because it confirms what smaller studies (including 2 of my own) have concluded for years. It also gives impetus to renewed efforts to attempt to link gambling disorder to particular genes or gene regions. To accomplish this will require large samples of patients with gambling disorder, depending on the method used (such as a genome-wide scan).

This finding was the culmination of many years of hard work. With a grant from the National Institute on Drug Abuse, my team was able to recruit 95 people with pathological gambling and 91 controls from the same community (who were recruited through random digit dialing methods). We gathered data on over 1,000 of their relatives, about 30% of whom were personally interviewed. The study subjects were all carefully assessed regarding their health, habits, emotional disorders, and gambling behaviors. If a relative chose not to participate or had died, we gathered data from the initial subject or other relatives for what constituted a proxy interview. Just about all of the psychiatric disorders that we looked at were excessive among those with pathological gambling compared with controls, such as major depression, alcohol disorders, and anxiety disorders. Among the relatives, mood disorders, alcohol and drug disorders, and anxiety disorders were excessive, in addition to gambling disorder.

This study also has allowed us to take an intensive look at the families of pathological gamblers as well. Multiple indices of dysfunction (eg, divorce) existed. Substance use disorders and antisocial behavior are common in these families and add to the dysfunction. These families are known for abuse and dysfunction, but we have also found that gamblers, as a group, are unhealthy and have poor lifestyle habits: they smoke, drink, and are physically inactive. One only needs to think about the smoke-filled rooms that most gamblers inhabit to get an idea of why their health may be poor. We are now looking at other aspects of these families, including the tendency for suicidal behaviors to cluster in them, and the excess of personality disorders, including borderline and antisocial personality disorders. We have documented through other studies just how impulsive these people are.

So, where do we go from here? We are now conducting a follow-up study of gamblers and controls to study how gambling behavior varies over time and to learn whether it spontaneously remits, as many gamblers describe occurring. As for genetic studies, I think our work will spur others (along with ourselves) to pursue a molecular approach. Will we ever find a gene for gambling? I personally doubt it, since gambling is a social construct, and it is hard to believe that gambling itself is genetically transmitted. However, it could be that what is transmitted is a propensity to be impulsive, to think without reflection, and to become “addicted” to substances or behaviors. I believe the next 10 years will be critical in following up on these findings and seeing where it leads. Presumably, if we know what causes a disorder, we are better able to design therapies for it. That is the hope.

Financial disclosure:Dr Black has received grant/research support from AstraZeneca and has received royalties from Oxford University Press, American Psychiatric Publishing, and UpToDate.