The American death rate increased for the first time in 10 years in 2015, ticking up from 723.2 deaths per 100,000 people to 729.5.
The last time the death rate increased was in 2005, amid a brutal flu season. The data from the National Center for Health Statistics surprised experts, the New York Times reports, as it is rare to see a national increase. Preliminary analysis indicates that heightened rates of Alzheimer’s, suicide and drug overdoses could have driven the increase, as well as a relatively flat rate of heart disease (which has declined every year since 1993).
Robert Anderson, the chief of mortality statistics at the National Center for Health Statistics, told the Times the numbers were significant, but added, “The question is, what does it mean? We really need more data to know. If we start looking at 2016 and we see another rise, we’ll be a lot more concerned.”