Boys with a low resting heart rate in their late teens run a higher risk of turning to a life of violent crime when grown, a study suggests.
The findings could lead to improved ways to stop certain people from indulging in crime before it is too late.
Experts say that low resting heart rate (RHR) is either an indicator of a chronically low level of psychological arousal, which may lead some people to seek stimulating experiences, or a marker of weakened responses to aversive and stressful stimuli, which can lead to reckless behaviour.
"Our results confirm that, in addition to being associated with aggressive and antisocial outcomes in childhood and adolescence, low RHR increases the risk for violent and nonviolent antisocial behaviours in adulthood," the authors conclude.
The findings were published online by JAMA Psychiatry.
Antti Latvala, of the Karolinska Institutet in Stockholm and the University of Helsinki in Finland, and his co-authors studied data on 710,264 Swedish men born from 1958 to 1991, who were followed for up to 35.7 years. Their average age was 18 when they had RHR and blood pressure measured.
Of these, 40,093 were convicted of a violent crime during the years they were followed.
The authors found that compared with 139,511 men with the highest RHR (83 beats per minute or more), the 132,595 men with the lowest RHR (60 beats per minute or less) had a 39 percent higher chance of being convicted of violent crimes and a 25 percent higher chance of getting convicted of nonviolent crimes.