IJCNMH ARCpublishing

Issue: Issue 4 (2017) – Supplement 3

Original Article

Association of p.Val158Met COMT polymorphism with paranoid ideation in drug addicts

Carolina Ribeiro, João Curto, Graça Areias, Adriana Belo, João Balhau, José Rocha Almeida, and Manuela Grazina
Introduction: Drug addiction is one of the most devastating brain disorders, involving the impairment of brain reward pathway. The enzyme catechol-O-methyltransferase (COMT) metabolizes dopamine and influences the reward pathway functioning. COMT activity is influenced by genetic variations, particularly the p.Val158Met (rs4680); the Met/Met genotype has been associated with a 40% reduction in enzyme activity. The aim of this study was to determine p.Val158Met COMT polymorphism in a Portuguese population of drugs addicts seeking treatment and its association with paranoid ideation. 
Methods: A group of 106 drug addicts seeking treatment were evaluated, upon written informed consent, taking into account their clinical history. Sixty patients were submitted to an evaluation protocol for neuropsychological assessment. Genetic screening for the COMT polymorphism p.Val158Met was performed. Control subjects (n=77) without clinical history of addiction were included, matching for age and socioeconomic status. Statistical analysis was performed (SPSS 19.0®) and significance was considered if p<0.05. 
Results: Significant differences were observed in genotype and allele frequencies between drug abusers and controls (p-value = 0.0068 and 0.0033, respectively). Moreover, paranoid ideation was associated with Met/Met genotype (p-value = 0.046). 
Conclusions: Drug addicts have a higher frequency of Val allele. The Met/Met genotype is associated with higher risk of developing paranoid ideation, probably due to the lower enzyme activity that leads to higher synaptic dopamine levels. The results are preliminary but significant for the study of genetic variability influencing drug addiction and are a relevant contribution for therapeutic strategies.

Keywords: Drug Addiction, COMT, Dopamine, Paranoid Ideation, Reward Pathway.

Special Issue on the Neurobiology of Mental Illness

International Journal of Clinical Neurosciences and Mental Health 2017; 4(Suppl. 3):S12
DOI: https://doi.org/10.21035/ijcnmh.2017.4(Suppl.3).S12
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