Why do opioid overdose deaths spike after cold snaps?
That's the mystery Brown University researchers set out to solve in a study of more than 3,000 opioid-related deaths in Connecticut and Rhode Island between 2014 and 2017.
The new analysis uncovered a 25% increase in opioid overdose deaths within three to seven days of freezing temperatures, compared to stretches when the temperature averaged 52 degrees Fahrenheit.
"Regardless of what is causing the correlation between cold weather and fatal overdoses, our findings suggest that agencies and organizations should consider scaling up harm-reduction efforts after a period of cold weather," said study leader Brandon Marshall. He is an associate professor of epidemiology at the Providence, R.I.-based university.
Opioids -- such as heroin, morphine and oxycodone (OxyContin) -- depress respiration and that can cause a deadly overdose. But, Marshall said in a university news release, "There may be a host of other risk factors that contribute to opioid overdose deaths, which could be avenues for effective interventions."
Those interventions might include public health messages to remind people to check on neighbors and loved ones who use opioids, and to warn users not to use the drugs when they are alone, Marshall said.
While the precise reasons for the uptick in overdoses after cold snaps are unclear, there are several ways cold weather may increase the risk, according to the researchers.
Both opioids and cold weather make breathing more difficult. Some opioids also reduce the temperature where shivering starts, making it harder to regulate your body temperature, the researchers explained.
Cold weather also changes behavior, they added. People may be more likely to be alone when they use opioids, meaning no one is with them to administer the overdose-reversal drug naloxone (Narcan).
Cold weather also may affect users' access to opioids. That could increase the risk that they will use drugs containing illicit fentanyl or those that are more potent than they're used to, the study authors suggested.
The study was published June 14 in the journal Epidemiology.
The U.S. National Institute on Drug Abuse has more about the opioid overdose crisis.