ADHD and smoking
Introduction Cigarette smoking is the leading preventable cause of death and disability in the United States. Annually, smoking leads to more than 400 000 premature deaths in the USA and nearly 5 million deaths worldwide [1]. In the USA alone, $150 billion in annual costs are attributable to smoking-related illnesses and lost worker productivity [2]. Several large-scale, epidemiological studies have reported that individuals who have psychiatric disorders are significantly more likely to smoke than individuals from the general population [3, 4]. The prevalence of smoking among individuals with a current psychiatric condition is nearly double that of individuals without current mental illness [4, 5]. While individuals who reported a psychiatric diagnosis in the past month make up approximately 30% of the US population, they consume an estimated 44.3% of all cigarettes [4]. The number of co-occurring psychiatric disorders in an individual is also associated with higher levels of nicotine dependence and greater withdrawal severity [4, 6]. Most population- and clinic-based studies of smoking/psychiatric illness comorbidity have excluded attention-deicit hyperactivity disorder (ADHD). This may be because ADHD is oten considered a disorder of childhood and is thus not included as a psychiatric condition category when studying samples of adults. However, in the few studies in which the disorder has been examined, ADHD shows comparable rates of comorbidity with cigarette smoking as other psychiatric disorders (approximately 40%) [7]. Moreover, recent evidence suggests that ADHD symptoms, even at levels below the threshold required to make a clinical diagnosis, are signiicantly associated with risk for smoking [8].