It is already well known that smoking increases the risk of many physical health problems such as heart disease, lung cancer and high blood pressure. However, a new study suggests that the habit can have a detrimental impact on mental health as well.

Researchers from Israel and Europe surveyed over 2,000 university students, who came from a range of socioeconomic and political backgrounds.

They found that students who smoked were up to three times more likely to have clinical depression than their non-smoking peers. In one university, 14% of smokers had clinical depression compared to 4% of their non-smoking peers, while in another, 19% of smokers had clinical depression compared to 11% of non-smokers.

The study found that irrespective of their economic or socio-political backgrounds, students who smoked had higher rates of depressive symptoms and scored lower in areas of mental health, such as social functioning, compared to non-smoking students.

"Our study adds to the growing body of evidence that smoking and depression are closely linked. While it may be too early to say that smoking causes depression, tobacco does appear to have an adverse effect on our mental health," commented Prof Hagai Levine of the Hebrew University of Jerusalem.

The researchers added that their findings "highlight the need for further research on the interaction between smoking, mental health and quality of life, with implications for prevention, diagnosis and treatment".

Details of these findings are published in the journal, PLOS ONE.