A new research has found that smoking has long been known to damage lungs and cause heart disease but it could also lower IQ.

According to reports of dailymail. co. uk, young people who smoke regularly are likely to have markedly lower intelligence levels than those who do not smoke, and according to the study of 20,000 young adults, the heavier the smoker, the lower the IQ.

It was found by the study that a typical 18- to 21-year-old smoker was found to have an IQ of 94, while non-smokers of the same age averaged 101.

Those who smoked more than a pack a day had particularly low IQs of around 90. An average intelligence IQ score ranges from 84 to 116 points.

The results come from a study of 20,000 young men conducted by the Sheba Medical Center at the Tel Hashomer Hospital in Israel.

It is unclear whether smoking causes IQ levels to drop or whether less intelligent people are simply more inclined to smoke, Mark Weiser, who led the research, said.

Weiser said, "It was really quite a straightforward study... We looked at cross-sectional data on IQ and smoking cigarettes, and looked at people's smoking status and their IQs."

He further added, "IQ scores are lower in male adolescents who smoke compared to non-smokers and in brothers who smoke compared to their non-smoking brothers. The IQs of adolescents who began smoking between ages 18 to 21 are lower than those of non-smokers. It's very clear that people with low IQs are the ones who choose to smoke. It's not just a matter of socioeconomic status - if they are poor or have less education." (With Inputs from Agencies)