By the numbers

2x

How much more likely under-21-year-olds who visited a physician in 2010 were to be diagnosed with a mental disorder than that age group in 1995, according to a November study online in JAMA Psychiatry.

23%

Percentage of orthopedic surgeons who have been trained to recognize and respond to domestic violence injuries, according to a September study in The Lancet. One in six injured women who go to orthopedic fracture clinics has experienced such violence in the past year, the study found.

135 million

How many people worldwide are expected to be living with dementia by 2050 compared with the 44.35 million estimated to be living with it today, according to Alzheimer's Disease International. By mid-century, 71 percent of those affected will live in low- and middle-income regions, such as Sub-Saharan Africa, the report also predicts.

6%

Percentage of the adolescents surveyed who reported using psychotropic medications in the past month, according to a December report from the Centers for Disease Control and Prevention. Most took either antidepressants or drugs to treat depression or attention-deficit/hyperactivity disorder.