U.S. overdose deaths involving psychostimulants other than cocaine, largely methamphetamine, increased 180% among adults under age 65 between 2015 and 2019, to 15,489, according to a study by the National Institute on Drug Abuse published this week in JAMA Psychiatry. The number of people reporting methamphetamine use increased 43% over the period, suggesting that increases in methamphetamine use disorder, frequent use and use of other drugs at the same time may be contributing to the rise in deaths, the authors said.