A new study suggests that quitting smoking can improve the mental condition of those suffering from depression and addiction.

Researchers from the Washington University School of Medicine led by Patricia A. Cavazos-Rehg surveyed 4,800 daily smokers. In that sample, the individuals who are addicted or are afflicted with psychiatric disorders showed the less likelihood of retaining those same problems after three years if they stopped smoking.

"Clinicians tend to treat the depression, alcohol dependence or drug problem first and allow patients to 'self-medicate' with cigarettes if necessary. The assumption is that psychiatric problems are more challenging to treat and that quitting smoking may interfere with treatment," Cavazos-Rehg said in a university press release.

After further analysis of the study, they discovered that quitting or reducing cigarette smoking has a direct positive effect on the participants' mental health. It was associated with a lower threshold for mood disorders and problems with alcohol and drugs.

"We don't know if their mental health improves first and then they are more motivated to quit smoking or if quitting smoking leads to an improvement in mental health. But either way, our findings show a strong link between quitting and a better psychiatric outlook," said Cavazos-Rehg added.

Conversely, those who were not suffering the depression or addiction were also less vulnerable to developing it if they had already stopped smoking. A lower percentage of 29 percent who quit compared to 42 percent of those who continued smoking suffered from depression, while alcoholism continued to affect 28 percent of the daily smokers compared to the 18 percent who dropped the smoking habit. Drug abuse, on the other hand, is also higher at 16 percent on the daily smokers as opposed to five percent of the quitters.

This study was published in the online journal Psychological Medicine.