Twin Research and Human Genetics


Association Between Single Nucleotide Polymorphisms in the Cannabinoid Receptor Gene (CNR1) and Impulsivity in Southwest California Indians

Cindy L. Ehlersa1 c1, Wendy S. Slutskea2, Penelope A. Linda3 and K. C. Wilhelmsena4

a1 Departments of Molecular and Experimental Medicine, and Molecular and Integrative Neurosciences, The Scripps Research Institute, La Jolla, California, United States of America.

a2 Department of Psychological Sciences, University of Missouri, Columbia, Missouri, United States of America.

a3 Genetic Epidemiology Laboratory, Queensland Institute of Medical Research, Brisbane, Queensland, Australia.

a4 Departments of Genetics and Neurology, The Carolina Center for Genome Sciences, and the Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, United States of America.


Impulsivity is a personality trait characterized by acting suddenly in an unplanned manner in order to satisfy a desire without consideration for the consequences of such behavior. There are several psychiatric disorders that include the term impulsivity as a criterion and, therefore, it has been suggested that impulsivity may be an important phenotype that may link a number of different behavioral disorders, including substance abuse. This study's aims were to determine if a significant association could be detected between the (AAT)n triplet repeat polymorphism as well as 5 single nucleotide polymorphisms (SNPs) in or near the CNR1 receptor gene and impulsivity in Southwest California ‘Mission’ Indians (SWC). Impulsivity was assessed using a scale derived from the Maudsley personality inventory, and blood samples were collected for DNA analyses from 251 individuals recruited from local Indian reservations. The estimated heritability (h2) for the impulsivity phenotype was 0.20 + 0.12 (p < .004). Impulsivity was significantly associated with the 6-repeat allele of the triplet repeat polymorphism (AATn/A6; p < .0001), as well as four SNPs in or near the CNR1 receptor gene: rs1535255 (p = .001), rs2023239 (p = .004), rs1049353 (p < .001) and rs806368 (p < .0006). These studies provide data to suggest that the CNR1 receptor gene may be significantly associated with impulsivity in SWC Indians.

(Received September 03 2007)

(Accepted October 02 2007)


c1 Address for correspondence: Cindy L. Ehlers, Ph.D., The Scripps Research Institute, Molecular and Integrative Neurosciences Department, 10550 North Torrey Pines Road, SP30-1501, La Jolla, CA 92037, USA.