Is depression really caused by a chemical imbalance in the brain? It’s a widespread belief, but a major new review of data on more than a 100,000 patients finds no connection between serotonin levels and depression. Experts think antidepressants may be helping patients in other ways. Read more

Olivia Newton-John dies at 73. A top hitmaker of the 1970s and 1980s, and star of films such as “Grease” and “Xanadu,” Newton-John also waged a private battle against breast cancer that began in the 1990s. She turned her struggle into advocacy for research against the disease. Read more

Ashton Kutcher reveals battle with debilitating vasculitis. The 44-year-old actor said that two years ago, the autoimmune disease caused him to lose his sight, hearing and even the ability to walk. He’s recovered, but feels “lucky to be alive.” Read more

When pot made legal, ODs from synthetic pot decline. Researchers discovered a 37% drop in poisoning reports for products like K2 and Spice in states that have approved recreational use of marijuana, compared to states where pot is still restricted. Read more