Psychiatry Research EG

Introduction Circadian rhythmic expression differs among individuals. These differences are often labeled as morningness–eveningness or chronotype. Three main phenotypic variants of human chronotype exist: morning type, neither type, and evening type. Nicotine is a psychoactive stimulant that is abundantly present in cigarettes. Few data are available about the possible associations between the stimulant effect of nicotine and the phase shift of circadian rhythm and chronotype of individuals abusing nicotine (smokers). Different brain pathways explain the associations between chronotypes and various addictive behaviors, although the impact of nicotine on cognition remains unclear. This study is based on the hypothesis that circadian typology is a risk factor for smoking and for higher levels of nicotine consumption, dependence, and associated cognitive changes in smokers. Aim This study aimed to estimate the possible associations between circadian typology and smoking. Measures quantifying nicotine dependence and smoking status were applied to the recruited sample. In addition, cognitive assessment of the sample was carried out. Participants and methods A representative sample of smokers (total N= 100) of both sexes were randomly selected. All patients had been smoking for at least 5 years. An age-matched and sexmatched control group of healthy nonsmokers was also recruited. Each participant was subjected to a clinical psychiatric interview using the Arabic version of the Mini-International Neuropsychiatric Interview. The chronotype of the participants was evaluated using the Horne and Ostberg Morningness–Eveningness Questionnaire. Cognition was assessed with the Montreal Cognitive Assessment scale. Smoking status was assessed with the Fagerstro¨m Test for Nicotine Dependence, the selfadministered Nicotine Dependence Syndrome Scale, and the Questionnaire of Smoking Urges. Results The majority of smokers were of neither typology, followed by moderately evening type. Smokers had statistically significant cognitive impairment in terms of visuospatial ability, verbal fluency, delayed recording, and total Montreal Cognitive Assessment score compared with nonsmokers. Sex affected chronotype, education, duration of smoking, and Fagerstro¨m level of dependence scale score. Higher level of nicotine dependence was associated with greater cognitive impairment in smokers.