Smokers have lower IQs than non-smokers, and the more one smokes the lower one’s IQ, research has found.
A study of 18-21 year old men in the Feb 2010 issue of Addiction showed that smokers’ IQs averaged 94, seven points lower than the 101 average of non-smokers. Those who smoked more than a pack of cigarettes a day averaged just 90 between them.
The study took data from more than 20,000 men before, during and after their compulsory service in the Israeli military. 28 per cent of their sample smoked one or more cigarettes a day, three per cent considered themselves ex-smokers, and 68 per cent said they never smoked.
The question remains: does smoking cause a lower IQ, does a lower IQ cause taking up smoking, or some other factor like a lower socio-economic class cause both smoking and a lower IQ.
Professor Mark Weiser of Tel Aviv University’s Department of Psychiatry argues that the relationship between a lower IQ and smoking is NOT due to socio-economic factors:
In the health profession, we’ve generally thought that smokers are most likely the kind of people to have grown up in difficult neighbourhoods, or who’ve been given less education at good schools. But because our study included subjects with diverse socio-economic backgrounds, we’ve been able to rule out socio-economics as a major factor.
The study also measured the effects of smoking in twin brothers. It is known that there is a large inherited aspect of intelligence (identical twins tend to have similar IQ levels), and twins tend to be raised in the same socio-economic environment. The researchers found here that in the case where one twin smoked, the non-smoking twin tended to have a higher IQ.
Professor Weiser argues that people with lower IQs have poorer decision-making skills when it comes to their health, and this results in them smoking. But there is also evidence that smoking damages neurogenesis in the brain, and may directly cause a reduction in intelligence, particularly heavy smoking.
The loss in IQ associated with smoking in this study was comparable to the gain in IQ that results from training with i3 Mindware – a considerable effect.
