“Smoking has been linked with depressive symptoms in adolescents, but data on secondhand smoking and depressive symptoms in low- and middle-income countries are scarce,” wrote Louis Jacob, Ph.D., of the University of Versailles Saint-Quentin-en-Yvelines in France and colleagues. “This is an important omission as enforcement of tobacco control policy legislation is weaker in [low- and middle-income countries] compared with high-income countries.”
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 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, and/or the effects of nicotine on neurotransmitters and inflammation.
“If corroborated by further longitudinal studies, these findings suggest that reducing [secondhand smoke] exposure may be important not only for the prevention of physical diseases such as ischemic heart disease, lung cancer, and asthma, but also for adolescent depressive symptoms in [low- and middle-income countries],” the researchers wrote.
(Image: iStock/boonchai wedmakawand)