In case you needed one more thing to worry about, researchers have found a correlation between a teenage boy's low heart rate and becoming a violent criminal later in life. But don't go checking anybody's pulse just yet.
Young men with low resting heart rates were almost 40 percent more likely to be convicted of a violent crime than young men of the same age with high resting heart rates, according to a September 2015 study published in JAMA Psychiatry.
Antti Latvala, PhD, of the Karolinska Institute, Stockholm, and the University of Helsinki, Finland, and coauthors examined the resting heart rates and blood pressure readings of more than 700,000 Swedish men born between 1958 and 1991 when they were around 18 years old.
Dr. Latvala and his team then looked at crime data and found that the more than 130,000 men with the lowest resting heart rates were 39 percent more likely to be convicted of a violent crime than the nearly 140,000 young men with the highest resting heart rates. The men with the lowest resting heart rates were also 25 percent more likely to be convicted of non-violent crimes.
"Antisocial and aggressive behavior has been associated with lower resting heart rate in children and adolescents. In fact, this association is so robust that low resting heart rate has been described as the best-replicated biological correlate of antisocial behavior in children and adolescents," Latvala says. "We were excited to find an association in the general population using representative information from nationwide registers."
But that doesn't mean there's anything to be worried about.
Heart Rate Can't Predict Future Criminal Behavior
"It's obvious that low resting heart rate by itself can't be used to determine future violent or antisocial behavior," Latvala says. "These are highly complex behaviors with multiple risk factors ranging from biological to societal levels."
In a large sample it can be observed that those with a lower heart rates tend to be more likely to commit crimes and engage in other risky behaviors in the future, but it's also important to note that the vast majority of men with low heart rates didn't commit crimes, Latvala adds.
Johanna Paola Contreras, MD, MSc, FACC, assistant professor of cardiology at The Zena and Michael A. Wiener Cardiovascular Institute at Mount Sinai, agrees that the study doesn't say much about a young man's potential to become a cold-blooded criminal.
"Heart rate varies from minute to minute and also with age. Adolescents are younger and very active, so they tend to have low resting heart rates," Dr. Contreras says.
It's extremely important to keep the difference between correlation and causation in mind, Contreras adds.
"In my opinion, the correlation reported occurred by chance and is not a true association. I would say this data represents one of those 'true, true but unrelated' scenarios we have all encountered in life," she says.
So definitely don't go freak out your son or significant other with a random pulse check. In fact, a low resting heart rate is often a good thing.
"I don't think spouses need to worry. They should look at their husbands as a whole person — not just look at one data point like their heart rate. Usually men with good exercise habits, good diet and low stress levels have lower resting heart rates — characteristics of a desirable partner, Contreras says. "Men with bad habits, inability to communicate, excessive exercise and passive behavior patterns can also have low resting heart rates. I doubt these men would be considered good life partners."