Problem gambling runs in families according to a University of Iowa study published online Feb. 24 in the journal Psychiatry Research.
The study also found an excess of alcoholism, drug disorders and antisocial personality disorder in families with pathological gamblers.
This is the first study of its kind to include detailed family interviews of relatives of persons with pathological gambling, said Donald W. Black, M.D., professor of psychiatry in the UI Roy J. and Lucille A. Carver College of Medicine.
"Something is being passed along in these families that increases the persons' likelihood of engaging in impulsive and ultimately self-destructive behavior. In some persons, it manifests as substance abuse, in others as antisocial behavior, and in others gambling, and often the three are combined," said Black, who has studied pathological gambling for the past eight years.
The study consisted of interviews of 31 pathological gamblers and 31 controls, and their respective first-degree relatives (parents, siblings and children).
"We looked at first-degree relatives because they theoretically share 50 percent of their genes with the pathological gambler or the control subject. If this disorder runs in families, it is most likely to cluster in those that you share more of your genes with," Black said.
Demonstrating that gambling runs in families is the first step in finding the gene or genes that underlie gambling, and Black hopes this study will lead to molecular genetic studies of pathological gambling. Further, Black believes that helping patients understand that pathological gambling runs in families will help them break the cycle.
The study found the average age of onset of pathological gambling was 36 years. For men, the average age was 34 years. For women, the problem developed at a later age, with an average age of onset of 39 years. Black said that women have a "compressed course," meaning that while they start gambling later in life, it reaches maximum severity more quickly.
More than half the pathological gamblers interviewed were either single, divorced or widowed, which was not true of the control group.
"Pathologic gamblers tend to have chaotic lives," Black said. "And when you add in other factors like alcoholism or antisocial personality disorder, the marital dysfunction becomes more understandable."