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.