Low resting heart rate tied to criminal behavior in men

Could a young man's resting heart rate predict his chance of committing violent crimes later in life? Possibly, according to a new study.

Researchers tracked criminal activity among more than 700,000 Swedish men whose resting heart rate was recorded at age 18. They found that low resting heart rate in late adolescence was associated with increased risk for violent criminality in adulthood. The results of the study were published today in JAMA Psychiatry.

"It is important to stress that the vast majority of men who have low resting heart rates do not commit crimes," the study's author, Antti Latvala, a postdoctoral researcher in the department of public health at the University of Helsinki in Finland, told HealthDay.

The authors also note that the study is only observational and does not prove cause and effect. But a clear connection between low resting heart rate and violent behavior does exist, they said.

Latvala and his team analyzed data from 710,264 men born born 1958 to 1991 with up to 35 years of follow-up. At age 18, the men had their resting heart rate and blood pressure measured as part of a physical conducted just before beginning compulsory military service.

The researchers defined high resting heart rate as greater than or equal to 83 beats per minute and low resting heart rate as less than or equal to 60 beats per minute.

The results showed that compared to the 139,511 men with the highest resting heart rate, the 132, 595 men with the lowest resting heart rate had a 39 percent higher chance of being convicted of violent crimes and a 25 percent increased risk of being convicted of nonviolent crimes. The researchers also took into account physical, cardiovascular, cognitive and socioeconomic variables.

Violent crimes included murder, assault, kidnapping, robbery and rape, while nonviolent crimes included drug dealing, theft and traffic violations. All criminal convictions were recorded in Sweden's crime register.

"In follow up analyses, we looked at the association with specific types of crime," Latvala said. "We found that low resting heart rate was a stronger predictor of severe violent criminality than of less severe violence."

Additionally, the results showed that low resting heart rate predicted exposure to assaults and accidents, including traffic crashes, falls and poisonings.

Previous research has showed that low resting heart rate is related to antisocial behavior in children and adolescents. The general thinking is that low resting heart rate is an indicator of a chronically low level of psychological arousal, which may lead some people to seek more stimulating experiences. It may also be a marker of weakened responses to stressful stimuli, which can lead to fearless behavior and risk taking.

Latvala said that future research should focus on the biological mechanisms of antisocial behavior. "Our results confirm the association between low resting heart rate and antisocial behavior across adulthood," he said. "Now that we know this is a real association, it will be possible to design experimental or quasi-experimental studies where we can try to test different hypotheses."

In an accompanying editorial, Adrian Raine, a professor of criminology, psychiatry and psychology of the University of Pennsylvania called the study "exceptional," but notes that it is limited. "There are many things that contribute to violence, not just biological factors like heart rate," he wrote.

"Yes, having a low heart rate raises the odds of committing a crime, and not just violent crime, all kinds of criminal and reckless behavior," Raine said. "But it doesn't mean that you will."

Finally, Latvala said that the findings might one day have implications for crime prevention and intervention efforts.

"In principle, physiological markers such as heart rate might be useful in combination with other well known risk factors for identifying individuals who have an elevated risk for antisocial behavior and violence," he said. "But it is uncertain whether the association with heart rate -- although it's a real phenomenon -- whether it is strong and specific enough for this task."