Tel Aviv University researchers have found that a study of 20,000 men ages 18-21 in the Israeli army found those who smoked tended to have a lower IQ.

Young male smokers are more likely to have lower IQs than their non-smoking peers, Mark Weiser of the university's department of psychiatry and the Sheba Medical Center at Tel Hashomer Hospital found.

It was also found by the study that in the case where one twin smoked, the non-smoking twin tested at a higher intelligence level.

Weiser said in a statement, "In the health profession, we've generally thought that smokers are most likely the kind of people to have grown up in difficult neighborhoods, or who've been given less education at good Schools."

He further added, "But because our study included subjects with diverse socioeconomic backgrounds, we've been able to rule out socioeconomics as a major factor." (With Inputs from Agencies)