Girls who smoke during their teenage years increase their risk for developing osteoporosis, the brittle bone disease, as older adults, a new study has found. Smoking has the greatest effect on the quality of bone in the hips and the lumbar, or lower, spine. Both areas are common sites for fracture in older women who have osteoporosis.

The researchers assessed the effects of smoking as well as depression and anxiety on bone mineral density (BMD) in 262 girls ages 11 through 19. Smoking, depression and anxiety have all been linked to lower bone mineral density in adults.

During the study, the girls received annual clinical exams over the course of three years. During each visit, doctors screened the girls with  dual energy x-ray absorptiometry, a test that measures total bone mineral content as well as the bone mineral density of the hip and lumbar spine. Physicians also screened the teens for depression and anxiety. Every three months, the girls' smoking levels were assessed during phone interviews.

Though all the girls in the study, both smokers and non-smokers, entered adolescence with equivalent levels of BMD in their lumbar spines and hips, this scenario gradually changed. Over time, teenage girls who smoked the most gained the least BMD in these areas.

The most depressed girls also had lower BMD in their spines, regardless of age, compared to girls who had fewer symptoms of depression. Levels of anxiety did not affect BMD.

Though teenage girls generally smoke at modest and highly variable rates during the course of a month, it is  “concerning that that even relatively low levels of smoking have a negative effect on bone accrual,” wrote the researchers at Cincinnati Children's Hospital Medical Center (CCHMC).

“If you look at a 19-year-old, the difference in lumbar-spine bone-mass density between non- versus daily smokers is similar to what an adolescent would normally gain in bone during one year,” said study researcher Lorah Dorn, director of research in the division of adolescent medicine at CCHMC. That BMD loss in smokers could translate into a higher risk for osteoporosis and fracture years later.

As girls move through their teenage years, they lay down 50 percent of their bone. In fact, teenage girls acquire as much bone during the first two years surrounding their first menstrual period as women lose during the last four decades of life, the researchers said.

Since the findings from this study may not apply to all teenage girls, additional research is needed, Dorn noted. Still, “the study may provide another health reason why smoking is not good,” she said.  “It should prompt healthcare providers to be vigilant about smoking and depressive symptoms potentially having a negative impact on bone during a crucial stage of development.”

The study is published today (December 4) in the Journal of Adolescent Health.

Pass It On: Teens who smoke or are depressed build less bone.

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