Vallerand IA, et al. - In this population-based retrospective cohort study over 6 million people (age 10-90 years) registered with The Health Improvement Network in general practices in the United Kingdom between January 1, 1986, and May 16, 2012, investigators assessed the bidirectional relationship between major depressive disorder (MDD) and alopecia areata (AA) ie, hair loss. They observed an increased risk of subsequently developing AA by 90% (hazard ratio, 1.90) due to MDD and vice-versa by 34%. They also recorded that antidepressants illustrated a protective impact on the risk of AA (HR, 0.57). This bidirectional relationship suggested common underlying inflammatory and genetic susceptibilities between the brain and skin.