Chronic effects of tobacco smoking on electrical brain activity: A systematic review on electroencephalography studies

Despite significant strides in reducing smoking prevalence globally, tobacco use remains a leading contributor to ill health and premature death worldwide. While the detrimental impacts of smoking on various organs are well- established, its specific effects on nervous system function remain an area of ongoing investigation. This systematic review delves into the neurobiological effects of smoking, particularly through the lens of resting-state electroencephalography (EEG). A systematic search was conducted in May 2024 in PubMed, Embase, and Web of Science databases, and all available evidence comparing resting-state EEG findings between smokers and nonsmokers was assessed. The 13 included studies investigated a total of 684 participants, with a median female percentage of of 25 % (range: 0-100), and the age of participants ranged from 18 to approximately 73 years. Alterations in the alpha band were the most prevalent findings observed in the EEG of smokers compared to nonsmokers, observed in 8 studies, suggesting changes in the attention and cognitive functions of smokers. However, findings regarding the specific direction and location of changes were not consistent. Additionally, changes in delta, theta, and beta bands were identified on a less frequent basis. There was evidence suggesting that the observed neural oscillation changes are influenced by various factors, including the number of cigarettes used, pack years of smoking, age of smoking initiation, and smoking cessation status. These findings underscore the multifaceted nature of the impact of smoking on brain activity, especially on cognition and the attentional system.