Smoking status and cognitive performance among vocational school students in Beijing, China

Introduction: In countries where smoking is associated with lower socioeconomic status, smokers tend to perform worse on cognitive tasks than non-smokers. China is now undergoing a similar process with a recent study showing that there is a reduced cognitive performance in middle aged but not in elderly smokers. We examined the links between smoking status and cognitive functioning among vocational school students in Beijing, China. Methods: A total of 213 students aged 16-20 (98 smokers and 115 non-smokers) were recruited from three vocational schools in Beijing. Participants completed three subtests of Wechsler Adult Intelligence Scale (WAIS) (information, arithmetic, digit span) and Dysexecutive Questionnaire (DEX). Smokers also completed a cigarette smoking questionnaire and Fagerstrom Test of Nicotine Dependence (FTND). Results: Smokers performed worse than non-smokers in tests of arithmetic and digit span forward (t = 4.25, 2.05, both P < .05). Scores on digit span backward did not differentiate smokers and non-smokers, but among smokers, the performance on this subtest was related to the age of starting smoking (r = 0.26, p < .001). Cognitive performance in smokers was not related to tobacco dependence or intensity of smoking. Compared to non-smokers, smokers had a higher total DEX score and higher scores on three of its five subscales (Inhibition, Knowing-doing dissociation and Social regulation, all p < .05). Another subscale, In-resistance, did not differentiate smokers and non-smokers, but differentiated smokers with lower and higher levels of nicotine dependence (t=-2.12, p < .05). Conclusion: Smokers performed worse on some cognitive tasks than non-smokers and scored higher on a questionnaire assessing executive dysfunction.