From studying Australian twins, new research says that genetic factors appear to influence the development of gambling disorders in both men and women.

These were the findings of Dr Wendy S. Slutske, a professor in the Department of Psychological Sciences at the University of Missouri-Columbia, and colleagues, which they wrote up in a paper published in the June issue of the Archives of General Psychiatry, one of the JAMA/Archives journals.

The authors wrote that various studies have already suggested that pathological gambling is influenced by genetic factors. One study found a lifetime history of similar problems among 8 per cent of men and women with a first degree relative with gambling disorders, compared with only 2 per cent who do not.

However although women now represent nearly half of patients being treated for pathological gambling, we know very little about what causes it in women or what the differences in causes might be between men and women.

So Slutske and colleagues set out to investigate the potential genetic and environmental factors that influence the development of disordered gambling in women, and the extent to which this differs to that of men.

They defined disordered gambling as the “full continuum of gambling-related problems that includes PG [pathological gambling] disorder” and measured it according to “lifetime DSM-IV PG symptom counts”.

DSM-IV stands for the fourth version of the Diagnostic and Statistical Manual of Mental Disorders which classifies mental disorders in terms of a common language and symptoms. It is published by the American Psychiatric Association.

For pathological gambling, the list of symptoms includes for example, needing to put increasing amounts of money into the habit to get the same thrill, having repeatedly tried to stop gambling and failed, feeling restless or irritable when trying to stop, using gambling as an escape, jeopardizing an important relationship or a job, and lying to cover up the habit.

For the study the researchers conducted structured telephone interviews with 4,764 men and women from 2,889 pairs of twins in the Australian Twin Registry and asked them questions to enable an assessment of disordered gambling and to assess similarity of childhood environments.

Some of the twins were identical (same genes) and some were not (shared genes). They were aged between 32 and 43 years and 57 per cent were women.

The results showed:

  • Many of the individuals were frequent gamblers: nearly all had gambled at least once, about half had gambled at least once a month, and one third had gambled at least once a week.
  • 2.2 per cent of the participants (3.4 per cent of the men and 1.2 per cent of the women) met criteria for pathological gambling.
  • 12.5 per cent (18.2 per cent of the men and 8.3 per cent of the women) had experienced at least one symptom of pathological gambling.
  • A link between genetic factors and gambling susceptibility: “the estimate of the proportion of variation in liability for DG due to genetic influences was 49.2 per cent”, wrote the authors.
  • No evidence that similar environments influenced susceptibility: “no evidence for shared environmental influences contributing to variation in DG liability”.
  • No evidence that the causes are different in men and women: “no evidence for quantitative or qualitative sex differences in the causes of variation in DG liability”.

Slutske and colleagues said the study shows for the first time that genes are as important in the development of disordered gambling in women as they are in men, and that the genes responsible are likely to overlap considerably among the sexes.

“The discovery of the specific genes and environments involved in the development of disordered gambling remains an important direction for future research,” they wrote.

A grants from the National Institutes of Health helped pay for the research.

“Genetic and Environmental Influences on Disordered Gambling in Men and Women.”
Wendy S. Slutske; Gu Zhu; Madeline H. Meier; Nicholas G. Martin.
Arch Gen Psychiatry, Vol. 67 No. 6, 624-630, June 2010.

Sources: JAMA Archives.

Written by: Catharine Paddock, PhD