Pathological gambling runs in families, says new research, "A Direct, Controlled, Blind Family Study of DSM-IV Pathological Gambling," published online in the March 2014 issue of the Journal of Clinical Psychiatry. Pathological gambling means gambling away and losing money needed for food, shelter, clothing, or family necessities of survival or having other severe, problematical gambling issues. But why does pathological gambling run in families when family members see how it's destroying the individual and breaking apart the family or leaving them destitute? Researchers have their work cut out for them: To find the genes that are linked to the gambling disorder.
The problem may be biologically related to PTSD, social anxiety disorder, and antisocial personality. A study by University of Iowa researchers confirms that pathological gambling runs in families and shows that first-degree relatives of pathological gamblers are eight times more likely to develop this problem in their lifetime than relatives of people without pathological gambling.
"Our work clearly shows that pathological gambling runs in families at a rate higher than for many other behavioral and psychiatric disorders," says Donald W. Black, MD, according to a June 16, 2014 news release, "Pathological gambling runs in families." Black is a professor of psychiatry in the UI Carver College of Medicine.
"I think clinicians and health care providers should be alerted to the fact that if they see a person with pathological gambling, that person is highly likely to have a close relative with similar or the same problem. That is a teaching moment and they should probably encourage the patient to let their relatives know that help is available."
Pathological gambling−gambling that is serious enough that it becomes a clinical issue−is a major public health problem that affects between 0.5 and 1.5 percent of American adults at some point during their lives
The University of Iowa (UI) study, which was the largest of its kind in the world to date, recruited and assessed 95 pathological gamblers and 91 control subjects, matched for age, sex, and level of education, from Iowa, as well as 1,075 first-degree adult relatives of the study participants (first-degree relatives include parents, siblings, and children.) Based on interviews and proxy interview material, the research team determined a gambling diagnosis for every person in the study.
Researchers found that 11 percent of the gambling relatives had pathological gambling themselves compared to 1 percent of the control relatives, which means that the odds are about eight times higher in gambling families for pathological gambling to run in those families compared to control families.
"People have always thought pathological gambling ran in families−anecdotal evidence certainly suggested it. But when you finally do a study like this, which is the largest of its kind, and come up with figures like this, it is quite striking," says Black, according to the news release. Black is lead author of the study.
When the researchers repeated the analysis to focus on problem gambling−a larger group of people than those with the more narrowly defined pathological gambling−they found that 16 percent of relatives of the pathological gamblers were problem gamblers compared to 3 percent of relatives of controls
The researchers also looked the relationships between pathological gambling and rates of other psychiatric and behavioral disorders among study participants and showed that relatives of pathological gamblers had higher rates of major depression, bipolar disorder, social anxiety disorder, substance use disorders, PTSD, and antisocial personality disorder.
Using statistical methods the team developed algorithms to determine which disorders are potentially biologically related to the gambling. Researchers found that antisocial personality, social anxiety disorder, and PTSD were more frequent in the relatives of pathological gamblers independent of whether the relative also had pathological gambling.
"This suggests that pathological gambling may share an underlying genetic predisposition with those disorders," Black says, according to the news release. This finding appears to confirm previous research and clinical observation suggesting that antisocial personality disorder could be biologically related to pathological gambling. However, Black was surprised by the connection between pathological gambling and social anxiety and a PTSD connection.
Pathological gambling, social anxiety, and PTSD (post-traumatic stress disorder) may be related, the study explains
"No one has ever published that and it's hard to know what to make of it yet," he says, according to the news release. The study also confirmed that mood disorders like major depression and bipolar disorder, as well as substance abuse, are common in pathological gamblers, but the analysis suggests that this probably is not due to a shared underlying biologic predisposition.
"I think our findings should give impetus to neuroscientists who conduct molecular genetic studies to really pursue this," Black says in the news release. "Maybe this situation provides a better chance of finding genes that are linked to the gambling disorder, and maybe that would pave the way for improving our understanding of the genetic transmission in general for psychiatric disorders, particularly in the realm of addiction."
In addition to Black, the University of Iowa research team included William Coryell, MD; Raymond Crowe, MD; Brett McCormick; Martha Shaw; and Jeff Allen, PhD. The study was funded by a grant from the National Institute on Drug Abuse (DA021361).