Teens who use nicotine are more likely to report symptoms of anxiety, depression and other mental health problems than their peers who don’t use nicotine. Those findings come from three studies in Sweden, published in the journal Nicotine and Tobacco Research. The results apply to nicotine in tobacco and non-tobacco products, with teen girls more likely to report symptoms than boys. Authors say nicotine altered communication between neurons in the brain—changes that persisted even after nicotine left the body. They note that other factors could also affect risk of mental health problems, including alcohol and substance use. The studies also raise concerns about newer nicotine products and their effect on developing brains.