Adolescents who have low resting heart rates are less vulnerable to
stress-provoked mental health problems than are adolescents with higher
resting heart rates.FIG1
The finding comes from Albertine Oldehinkel, Ph.D., a professor of
psychiatric epidemiology at the University Medical Center Groningen in the
Netherlands, and her coworkers. Results were posted online in Biological
Psychiatry on February 14.
Oldehinkel and her team measured the resting heart rates of nearly 1,500
11-year-olds, and assessed them for internalizing mental health problems such
as anxiety, depression, and somatic complaints and for externalizing problems
such as aggression and rule-breaking behaviors.
When the youngsters were age 14, the researchers again evaluated them for
these mental health problems. Also, at that time, the subjects' parents were
asked to rate how stressful their children's lives had been during the
previous two years and whether their children had experienced various adverse
situations during the previous two years, such as chronic illness, a lot of
pressure at school, financial problems, lack of friends, or bullying. Finally
the researchers looked for links between the youngsters' resting heart rates
at age 11, their stressor scores, and their mental health outcomes at age
The researchers found that high stressor scores predicted more severe
mental health problems in adolescents with intermediate or high heart rates
than in adolescents with low heart rates. The difference was statistically
Furthermore, these findings remained significant even when the subjects'
mental health problems at the start of the study were considered and when
internalizing or externalizing mental health problems were considered. And
although boys had more externalizing problems than girls did, findings were
not significantly different for boys and girls.
Thus the study indicates that "low heart rate is a marker of
resilience to the effects of environmental challenges in early
adolescence," Oldehinkel and her colleagues concluded.
A question now, however, is why, they wrote.
A low-resting heart rate undoubtedly reflects an underaroused involuntary
nervous system in the face of stress. But why is the involuntary nervous
system underaroused in such conditions? Is it due to the brain's major
response center to threatening stimuli—the amygdala—keeping"
its cool" in the throes of stress? Is it due to the adrenal
glands putting out less stress hormone in the throes of stress? As Oldehinkel
told Psychiatric News, "One of the things we will now examine
is how low resting heart rate is related to various psychophysiological stress
Still another question that needs to be answered, they indicated, is this:
if a low resting heart rate indeed helps buffer youngsters against
externalizing mental health problems, how come other investigators have found
a low resting heart rate in antisocial youngsters? After all, antisocial
behaviors are externalizing mental health problems. Oldehinkel and her team
admit that they currently have no answer to this seeming paradox. However,
they suspect that the answer might lie in the amygdala.
"Damage to the amygdala has been found to prevent danger stimuli from
eliciting arousal and distress, but also to increase the probability of
proactive aggression in nonthreatening circumstances. An underactive amygdala
could hence underlie both reactive and proactive behaviors."
Still another challenge, the researchers pointed out, "will be to
investigate whether interventions to lower heart rate help increase stress
The study was funded by the Netherlands Organization for Scientific
Research and the Department of Justice, Scientific Research, and Documentation
An abstract of "Low Heart Rate: A Marker of Stress Resilience.
The TRAILS Study" can be accessed at<www.journals.elsevierhealth.com/periodicals/bps>
under "Articles in Press." ▪