The vulnerability of developing addictions is associated with genetic factors and personality traits. The predisposing genetic variants and personality traits may be common to all addictions or specific to a particular class of addiction.
To investigate the relationship between genetic variances, personality traits, and their interactions in addiction are important. We recruited 175 opiate-dependent patients, 102 alcohol-dependent patients, and 111 healthy controls. All participants were diagnosed using DSM-IV criteria and assessed with Tridimensional Personality Questionnaire (TPQ). The dopamine D2 receptor (DRD2), 5-HTT-linked promoter region (5-HTTLPR), and aldehyde dehydrogenase 2 (ALDH2) genes were genotyped using PCR.
The genotype frequency of the 5-HTTLPR and ALDH2 was significantly different between the patients and controls (P = 0.013, P < 0.001, respectively), and borderline significant (P = 0.05) for DRD2 polymorphism. Both Novelty Seeking (NS) and Harm Avoidance (HA) scores were higher for patients (P < 0.001).
After stratification by candidate genes, addicts with ALDH2 *1/*1 interacting with the low-functional group of DRD2 and 5-HTTLPR genes have higher HA traits, whereas addicts with ALDH2 *1/*2 or *2/*2 and low-functional group of DRD2 and 5-HTTLPR genes have higher NS traits.
We concluded that addicts, both alcohol- and opiate-dependent patients, have common genetic variants in DRD2 and 5-HTTLPR but specific for ALDH2. Higher NS and HA traits were found in both patient groups with the interaction with DRD2, 5-HTTLPR, and ALDH2 genes.
The ALDH2 gene variants had different effect in the NS and HA dimension while the DRD2 and 5-HTTLPR genes did not.
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