Teenagers who claim that they smoke to improve the mood could actually be getting the opposite results with every cigarette they inhale as a new study suggests that smoking actually enhances the depressive symptoms among teens.

A study conducted using data from 662 students in grades seven and 11 across Canada suggests that smoking actually caused them to slip further into depression instead of improving their moods.

The students were asked to complete a set of 20 questionnaires that covered aspects related to their use of cigarettes to affect their mood. The participants were divided randomly into three groups comprising non-smokers, those who used cigarettes to self-medicate and smokers who were using cigarettes as a habit and not just to self-medicate, enhance their mood.

The researchers conducting the study, published in the online edition of the medical journal Addictive Behaviors, said they measured the depressive symptoms using a scale that asked the teens a series of questions related to their well-being.

They asked the volunteers to state how often they felt lethargic, had trouble falling asleep or staying asleep and how many times they felt sad or depressed. In addition, the questions related to feelings of hopelessness about the future, a feeling of nervousness or tension and excessive worry.

"Smokers who used cigarettes as mood enhancers had higher risks of elevated depressive symptoms than teens who had never smoked," says study co-author Jennifer O'Loughlin, a professor in the social and preventive medicine department at the University of Montreal and a scientist at the University of Montreal Hospital Research Centre.

"Although cigarettes may appear to have self-medicating effects or to improve mood, in the long term we found teens who started to smoke reported higher depressive symptoms," lead author Michael Chaiton, a research associate at the Ontario Tobacco Research Unit of the University of Toronto, said in the news release.

"It's important to emphasize that depressive symptom scores were higher among teenagers who reported emotional benefits from smoking after they began to smoke," the release said.