According to the researchers, 28 percent of the study participants smoked at least one cigarette a day, around 3 percent said they were ex-smokers, and 68 percent had never smoked.

The smokers had significantly lower intelligence test scores than non-smokers, and this remained true even after the researchers accounted for socioeconomic status measured by how many years of formal education a recruit’s father had completed.

The average IQ for non-smokers was about 101, while it was 94 for men who had started smoking before entering the military.

IQ steadily dropped as the number of cigarettes smoked increased, from 98 for people who smoked one to five cigarettes daily to 90 for those who smoked more than a pack a day.

The size and scale of this study, as well as its provocative findings, are sure to generate discussion and debate among the scientific community.

I have no basis to evaluate the scientific claims, and I’m not going to try. But I’m very sceptical, for one reason: Does anyone really find it believable that 68% of Israeli teenagers have never smoked?