I'll drink to that...in moderation
Massachusetts General Hospital
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For the first time, researchers
found that alcohol, in light to moderate quantities, was associated with
long-term reductions in stress signaling in the brain. This impact on the
brain's stress systems appeared to significantly account for the reductions in
cardiovascular events seen in light to moderate drinkers participating in the
study. Findings are published in the Journal of the American College of Cardiology.
"We are not advocating the use of alcohol to reduce the risk of heart attacks or strokes because of other concerning effects of alcohol on health," says senior author and cardiologist Ahmed Tawakol, MD, co-director of the Cardiovascular Imaging Research Center at Massachusetts General Hospital.
"We wanted to understand how light to moderate drinking reduces
cardiovascular disease, as demonstrated by multiple other studies. And if we
could find the mechanism, the goal would be to find other approaches that could
replicate or induce alcohol's protective cardiac effects without the adverse
impacts of alcohol."
Previous
epidemiological studies have suggested that light to moderate alcohol
consumption (1 drink per day for women and 1 to 2 drinks per day for men) is
associated with a lower risk of cardiovascular disease. But it was unknown
whether alcohol was inducing cardiovascular benefits, or whether light/moderate
drinkers' health behaviors, socioeconomic status, or other factors protected
their hearts.
The study, led by K Mezue and M Osborne, included more than 50,000 individuals enrolled in the Mass General Brigham Biobank. The first part of the study evaluated the relationship between light/moderate alcohol consumption and major adverse cardiovascular events after adjusting for a range of genetic, clinical, lifestyle, and socioeconomic confounders.
The researchers found that
light/moderate alcohol consumption was associated with a substantial reduction
in the risk of cardiovascular disease events, even after accounting for those
other factors.
Next,
they studied a subset of 754 individuals who had undergone previous PET/CT
brain imaging (primarily for cancer surveillance) to determine the effect of
light/moderate alcohol consumption on resting stress-related neural network
activity.
The brain imaging showed reduced stress signaling in the amygdala, the brain region associated with stress responses, in individuals who were light to moderate drinkers compared to those who abstained from alcohol or who drank little.
And
when the investigators looked at these individuals' history of cardiovascular
events, they found fewer heart attacks and strokes in light to moderate
drinkers. "We found that the brain changes in light to moderate drinkers
explained a significant portion of the protective cardiac effects," says
Tawakol.
It's long been known that alcohol reduces the amygdala's
reactivity to threatening stimuli while individuals are drinking. The current
study is the first to indicate that light to moderate alcohol consumption has
longer-term neurobiological effects in dampening activity in the amygdala,
which may have a significant downstream impact on the cardiovascular system.
"When
the amygdala is too alert and vigilant, the sympathetic nervous system is
heightened, which drives up blood pressure and increases heart rate, and
triggers the release of inflammatory cells," explains Tawakol. "If
the stress is chronic, the result is hypertension, increased inflammation, and
a substantial risk of obesity, diabetes, and cardiovascular disease."
Finally,
the investigators examined whether light/moderate alcohol would be even more
effective at reducing heart attacks and strokes in people who are prone to a
chronically higher stress response, such as those with a history of significant
anxiety. They found that, within the 50,000-patient sample, light to moderate
drinking was associated with nearly double the cardiac-protective effect in
individuals with a history of anxiety compared with others.
Yet
while light/moderate drinkers lowered their risk for cardiovascular disease,
the study also showed that any amount
of alcohol increases the risk of cancer. And at higher amounts of alcohol
consumption -- more than 14 drinks a week -- heart attack risk started to
increase while overall brain activity started to decrease (which may be
associated with adverse cognitive health).
The
authors concluded that research should focus on finding new interventions that
reduce the brain's stress activity without the deleterious effects of alcohol.
The research team is currently studying the effect of exercise,
stress-reduction interventions such as meditation, and pharmacological
therapies on stress-associated neural networks and how they might induce
cardiovascular benefits.
Co-authors
include Kenechukwu Mezue and Michael T. Osborne.
This study was supported by the National Institutes of Health.