Smokers have lower IQs

- Telegraph

Smokers have lower IQs than those who abstain, with intelligence decreasing the more one smokes, researchers have found.

A study of 18 to 21-year-old men revealed that the IQs of smokers averaged 94 – seven points lower than non-smokers on 101.


IQ scores in a healthy population of young men fall between 84 and 116, but those who smoked more than a pack of cigarettes a day averaged just 90 between them.

Researchers in Israel took data from more than 20,000 healthy men before, during and after they spent time in the Israeli military.

About 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.

Professor Mark Weiser, of Tel Aviv University's Department of Psychiatry, said: "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 effects in twin brothers – and in the case where one twin smoked, the non-smoking twin registered a higher IQ on average.

Prof Weiser said: "People on the lower end of the average IQ tend to display poorer overall decision-making skills when it comes to their health.

"People with lower IQs are not only prone to addictions such as smoking. These same people are more likely to have obesity, nutrition and narcotics issues.

"Our study may help parents and health professionals help at-risk young people make better choices."

The study was reported in a recent version of the journal Addiction.