<b>Background:</b> Several studies have revealed significant associations between single nucleotide polymorphisms (SNPs) in the cannabinoid receptor 1 (<i>CNR1</i>) gene and a broad spectrum of psychiatric disorders such as major depressive disorder (MDD), attention deficit hyperactivity disorder (ADHD), and schizophrenia.
Given the preclinical and clinical evidence regarding the associations between cannabinoid systems and both opiate dependence and psychiatric disorders, we chose to address whether one single nucleotide polymorphism (SNP) of the cannabinoid receptor type 1 gene (CNR1) named rs2023239 would be associated with lifetime MDD and SB in a population of opiate-dependent outpatients remitted under stable methadone treatment.
However, many works have repeatedly associated polymorphisms in the CNR1 and FAAH genes with drug-related behaviours; this suggests that these genes should be examined in further genetic studies focusing on drug addiction and other psychiatric disorders.
The cannabinoid receptor gene (CNR1) is a positional candidate gene due to its location near an identified ADHD linkage peak on chromosome 6, its role in stress and dopamine regulation, its association with other psychiatric disorders that co-occur with ADHD, and its function in learning and memory.
The intragenic CNR1 polymorphism 1359(G/A) should be useful for association studies in neuro psychiatric disorders which may be related to anandamide metabolism disturbances.