A new study by a team at Tel Aviv University in Israel found that young men who smoke are less intelligent than those who have never smoked.
The research is published on the website American Friends of Tel Aviv University (AFTAU). Researchers studied 20,000 young Israelis aged 18 to 21 years. They found that the more a person smokes, the lower their intelligence quotient (IQ).
In addition, participants who had a lower IQ were more likely to have other dependencies.
The IQ of a young healthy man is between 84 and 116. However, heavy smokers had an average of 90, those who smoked less scored 94, while non-smokers scored an average of 101 on IQ tests.
Prof Mark Weiser from Tel Aviv University said: "People on the lower end of the average IQ tend to display poorer overall decision-making when it comes to their health."
Researchers hope that this data will encourage professionals to better educate young people about various dependencies.