Deaths from the nation’s opioid crisis overshadow another nightmare for communities and families: the long-term health effects of nonfatal overdoses.

Researchers at the Dana and David Dornsife School of Public Health explored data on opioid overdose survivors, finding that repeated overdosing can lead to neurodegeneration resembling Alzheimer’s disease, cognitive and memory problems, and risky behaviors that may lead to future overdoses.

A team including Janna Ataiants, a senior research scientist, and Stephen Lankenau, a professor at Dornsife, gained new insights into the long-term consequences of repeated opioid overdose.

“We found strong evidence in the literature that opioid overdoses lead to these Alzheimer’s-like pathologies in the brain,” Lankenau says. “We also know that these processes in the body may progress for decades before these symptoms are evident,” given lower rates of health care access for many opioid users.

Published in the International Journal of Drug Policy, the study notes that rising fatal overdoses “might be only the visible tip of a looming iceberg,” since only 3–4% of all overdoses are fatal.