After analyzing 20,221 smoking questionnaires, researchers were able to conclude that male adolescents who smoke cigarettes had lower cognitive test scores compared to non-smokers.
These results were published in the journal Addiction in 2009.
The authors of this study analyzed data from smoking questionnaires and standardized cognitive tests given to Israeli military recruits. They found that those who smoked tended to have lower IQ scores than those who did not smoke, even when controlling for variables such as soci0-economic status.
The authors conclude their article by stating that,
poor cognitive functioning is a significant risk factor for cigarette smoking in male adolescents […] Adolescents with poorer scores on cognitive tests might benefit from programmes designed to prevent smoking.
Weiser, M., Zarka, S., Werbeloff, N., Kravitz, E. & Lubin, G. (2009). Cognitive test scores in male adolescent cigarette smokers compared to non-smokers: a population-based study. Addiction, Vol 105: 358–363.