Association of Plasma Dopamine and Norepinephrine Levels and Cannabis Use among Male Cannabis Smokers

Abstract

Background: Many studies have employed both direct and indirect methods of measuring the brain dopaminergic activity in relation to drug dependence, internet addiction and other disorders in which dopamine signalling has been implicated. However, only a few scientific reports have found a relationship between plasma dopamine and/or norepinephrine levels and addiction. Objective: The present work was aimed at determining the association between plasma dopamine level and consumption of cannabis as the most widely used illicit drug in the world. Methods: One hundred and six participants with cannabis use disorder based on International Classification of Diseases version 10 (ICD-10) were recruited for the study. Screening for current cannabis use disorder was done using Cannabis Use Disorder Identification Test (CUDIT). Cannabis dependence was assessed using the Severity of Dependence Scale (SDS). Venous blood samples were taken from the subjects to assay for the plasma dopamine by enzyme-linked immunosorbent assay (ELISA) method. Results: There was a high correlation between plasma dopamine and SDS scores with plasma dopamine accounting for more than 31% of the variance in SDS scores. However, the relationship between plasma dopamine and current cannabis use disorder was not strong as it accounts for just more than 9% of the variance in CUDIT scores. There was a relationship found between plasma norepinephrine and SDS scores. Plasma norepinephrine only accounts for about 5% of the variance in SDS score while there was virtually no association between plasma norepinephrine and CUDIT scores. Conclusion: Higher plasma dopamine level was found to be significantly associated with cannabis use and dependence as measured by SDS but less associated with current cannabis use disorder as measured by CUDIT.