Low novelty seeking and high self directedness scores in alcohol-dependent patients without comorbid psychiatric disorders homozygous for the A10 allele of the dopamine transporter gene

Abstract

The gene for the human dopamine transporter DAT1 displays several polymorphisms, including a 40-bp variable number of tandem repeats (VNTR) ranging from 3 to 13 copies in the 3'-untranslated region (UTR) of the gene. Some hints for an association of certain VNTR with psychiatric disorders, behavioural problems and temperament traits have been found. This study explored possible associations between the most frequent DAT1 polymorphism, namely the A10 VNTR, and personality traits as measured by the Temperament and Character Inventory (TCI) and the NEO Five Factor Inventory (NEO-FFI) in alcohol-dependent patients (ADP). One hundred and forty-four ADP and 144 age-, educational level- and sex-matched controls (CO) were genotyped and interviewed with the TCI and NEO-FFI. ADP showed higher neuroticism, lower extraversion, lower openness, lower agreeableness and lower conscientiousness than CO on the NEO-FFI and higher scores in harm avoidance, reward dependence and self transcendence and lower scores in self directedness and cooperativeness on the TCI than controls. There were no genetic links regarding those personality traits, the diagnosis of alcohol dependence and the VNTR. Only in a subgroup of ADP, those without psychiatric co-diagnoses and homozygous for A10, significantly lower scores in novelty seeking and higher scores in self directedness than in all the other ADP and CO could be detected. Summarizing, the 40-bp VNTR did not help to differentiate between ADP and CO, but might contribute to some personality dimensions in certain ADP subgroups.