Daniela Sabbatini S. Lobo^1,2, Homero Pinto Vallada¹, Joanne Knight³, Silvia S. Martins⁴, Hermano Tavares¹, Valentim Gentil¹, James L. Kennedy².
The 61st Annual Convention of the Society of Biological Psychiatry, Toronto, Canada, May 18th-20th, 2006
1. Institute of Psychiatry, University of São Paulo, São Paulo – SP, Brazil
2. Neurogenetics Section at the Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada
3. Social and Genetics Developmental Psychiatry, Institute of Psychiatry, Kings College of London, London, United Kingdom
4. Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD

Background: Molecular genetic studies of pathological gambling (PG) have associated polymorphisms in dopamine receptor genes to PG. Using a family-based association study design we investigated the relationship of functional polymorphisms in dopamine receptor genes (DRD1 -800 T/C, DRD2 Taq AI, DRD3 ser9gly; DRD4 exon III VNTR, and DRD5 (CA) repeat) with PG.

Methods: We evaluated 140 patients (mean age ± SD=40 ± 8.9 years old; 70 males, 70 females) who fulfilled DSM-IV criteria for PG and 140 non-gambler siblings (mean age ± SD= 40 ± 9.8 years old; 70 males, 70 females). Pathological gamblers were excluded if they met lifetime diagnostic criteria for bipolar disorder type I. Lifetime history of psychosis or neurological diseases were considered as exclusion criteria for both groups. One functional polymorphism on each of the dopamine receptor genes was chosen for analysis to reduce multiple testing. Pedigree disequilibrium tests (PDT) were performed through UNPHASED. A 2-tailed significance level of p<0.05 was adopted.

Results: An association of PG and allele 1 of DRD1 -800T/C was found (p=0.03). None of the other polymorphisms was associated to PG.

Conclusions: These findings could be regarded as evidence of the involvement of DRD1 in the development of PG. Recently, PG has been considered as a behavioral addiction. Investigation on the functional aspects of the D1 receptor has focused on its involvement in place preference. As pathological gamblers describe that places and situations related to gambling often elicit craving, it is possible that DRD1 mediates craving in PG