Secondhand Smoke May Raise Risk of Depressive Symptoms in Adolescents

Adolescents in low- and middle-income countries who are exposed to secondhand smoke may be more likely to develop symptoms of depression, a study in the American Journal of Preventive Medicine has found. The risk is also dose-dependent, with greater exposure associated with higher risk.

“Better implementation of smoke-free air policies and strategies aiming at reducing the number of smokers in low- and middle-income countries may lead to reductions not only in physical health problems such as lung cancer, cardiovascular diseases, and COPD at the population level, but also depressive symptoms among adolescents,” lead author Louis Jacob, Ph.D., a resident in physical rehabilitation and medicine of the University of Versailles Saint-Quentin-en-Yvelines in France, told Psychiatric News.

The researchers analyzed data from the 2003-2008 Global School-Based Student Health Survey of more than 37,000 adolescents aged 12 to 15 years who had never smoked and who lived in 22 low- or middle-income countries. To determine participants’ exposure to secondhand smoke, they were asked, “During the past seven days, on how many days have people smoked in your presence?” To determine whether participants had experienced symptoms of depression, they were asked, “During the past 12 months, did you ever feel so sad or hopeless every day for two weeks or more in a row that you stopped doing your usual activities?”

Overall, 53.6% of the participants had been exposed to secondhand smoke on at least one day in the past week, and 24.5% had experienced depressive symptoms in the past year. Nearly 29% of participants who were exposed to secondhand smoke every day over the past week had experienced depressive symptoms compared with 23% of those who were not exposed to secondhand smoke. Compared with those who were not exposed to secondhand smoke over the previous week, those who were exposed on at least three days were 48% more likely to have experienced depressive symptoms, while those who were exposed on all seven days were 63% more likely to have experienced depressive symptoms.

The results varied little from country to country, suggesting that they may be applicable to other low- and middle-income countries, but whether they apply to high-income countries remains to be seen, Jacob said. However, he noted that those who live in disadvantaged neighborhoods may be exposed to higher levels of secondhand smoke, regardless of country.

“Psychiatrists and other mental health professionals should be aware of this and may use this information to identify adolescents who are at increased risk for depression,” Jacob said.

The researchers wrote that the increased risk of depressive symptoms in adolescents exposed to secondhand smoke may stem from increased levels of perceived stress because of physical discomfort, the association between secondhand smoke and chronic physical conditions in childhood and adolescence such as asthma, or the effects of nicotine on neurotransmitters and inflammation.

The work of one researcher in the study was supported in part by the ISCIII-General Branch Evaluation and Promotion of Health Research and the European Regional Development Fund. ■