Smoking and depression contribute to low bone mass

Adolescent girls who smoke or who are anxious or depressed are at higher risk for low bone mineral density (BMD) in the hip and lumbar spine that could lead to osteoporosis and bone fractures as they grow older.

In a study to determine the impact of these behaviors on bone health, investigators recruited 262 healthy teenaged girls aged from 11 to 19 years from a health clinic in a large children’s hospital and the surrounding community and enrolled them in 4 age cohorts: 11, 13, 15, and 17 years. Girls were seen for 3 annual onsite visits and participated in phone interviews at 3-month intervals between visits. Bone accrual trajectories were estimated for total-body bone mineral content and for lumbar spine and total hip BMD using dual energy x-ray absorptiometry.

Smokers in the groups began the study with equivalent levels of lumbar spine and total hip BMD; however, their accrual of overall BMD was significantly lower as smoking frequency increased between ages 13 and 19 years. Girls with higher levels of depression had significantly lower lumbar spine BMD across ages 11 to 19 years. Depression symptoms had no effect on total body bone mineral content nor did alcohol intake affect any bone outcome.

Research has shown that more than 50% of a woman’s bone accrual occurs during adolescence. Development of postmenopausal osteoporosis can be traced to the periods of bone growth during these teenaged years, so early steps to maximize bone mineral development are key to its prevention.

The National Osteoporosis Foundation estimates that 10 million Americans already have osteoporosis and another 34 million are at risk. Two million bone fractures were attributed to osteoporosis in 2005, projected to rise to 3 million fractures each year by 2025.