Comparative Assessment of Salivary Dopamine and Acetylcholinesterase Levels in Smokers and Non-Smokers

Background: Nicotine, the principal psychoactive compound in tobacco, alters key neurochemical pathways, particularly those involving dopamine and acetylcholinesterase (AChE). These neurotransmitter changes may underlie the development of nicotine dependence and its cognitive and behavioral consequences. Comparing these biomarkers in smokers and non-smokers provides insight into the neurophysiological impact of chronic tobacco use. Objective: To assess and compare salivary dopamine levels and acetylcholinesterase (AChE) activity in smokers and non-smokers. Methods: An in vivo cross-sectional study was conducted among 240 healthy male participants aged 30 to 35 years, comprising 120 smokers and 120 non-smokers. Salivary levels of dopamine and AChE were measured using enzyme-linked immunosorbent assay (ELISA). Due to non-normal data distribution, the Mann-Whitney U test was used for statistical analysis, with significance set at p<0.05. Results: Smokers demonstrated significantly higher AChE activity (mean: 126.38 nmol/l) compared to non-smokers (mean: 112.9 nmol/L; p<0.001), suggesting altered cholinergic function. Dopamine levels were also significantly elevated in smokers (mean: 29.84 ng/ml) versus non-smokers (mean: 23.83 ng/ml; p = 0.002), indicating stimulation of the dopaminergic system likely linked to nicotine exposure. These results underscore the biochemical influence of chronic smoking on neural regulation and addiction pathways. Conclusion: The study found elevated salivary dopamine and AChE levels in smokers, indicating that nicotine use may contribute to both dopaminergic overactivation and cholinergic dysregulation. These neurochemical changes may reinforce addiction and impair cognitive processes. The findings support the need for neurobiologically informed smoking cessation strategies. Further research should investigate whether these biochemical alterations are reversible following smoking cessation.