Heavy drinking can cause brain abnormalities that could increase the risk for cognitive decline.
- The
full effects of drinking are something experts are still trying to
understand.
- One
study discovered that heavy and former heavy drinking was associated with
brain abnormalities like hyaline arteriolosclerosis and neurofibrillary
tangles.
- The results also suggested that the effects of alcohol consumption are mediated by hyaline arteriolosclerosis, which may then affect people’s cognitive function.
According to the
One area of ongoing
research is how alcohol can affect the brain. Published in Neurology, a recent
study explored the impact of alcohol consumption on various aspects of the
brain, specifically dementia-related neuropathologies.
It found that moderate, heavy, and former heavy
drinking were all associated with
Former heavy drinking was
also linked to having a lower brain mass ratio and poorer cognitive abilities
compared to never drinking. While more research is needed, the results indicate
the possible damaging effect of alcohol on the brain.
This study was
a cross-sectional population-based autopsy study conducted in Brazil.
Researchers were able to examine the brains of 1,781 participants.
These brains were
ultimately from the Sao Paulo Autopsy Service and part of the Biobank for Aging
Studies. It specifically excludes brain samples where someone died due to
trauma.
The average age of
participants was around seventy-five years old, and the sample was ethnically
diverse. Participants were at least fifty and had a next of kin who had been
contacting them at least weekly in the 6 months before their death.
Researchers did exclude
some potential participants, including those with major acute brain lesions or
those who did not have any data on alcohol consumption.
Researchers were able to
gather data from next of kin regarding factors like participants’ medical
histories, alcohol consumption, and the presence of dementia.
They divided participants
into groups based on the level of alcohol they consumed. There were never
drinkers, moderate drinkers, heavy drinkers, and formerly heavy drinkers.
For this research, 1 dose
of alcohol was 14 grams (g). Moderate drinkers had up to 7 doses of alcohol in
a week, while heavy drinkers had 8 or more doses in a week.
Former heavy drinkers were
heavy drinkers who had ceased drinking up to 3 months before their deaths
occurred. Of all participants, 965 never consumed alcohol.
Researchers then sought to
examine the brains for several changes, including those that indicated
Alzheimer’s disease. They were also able to determine brain weight.
Overall, the results showed worse outcomes related to alcohol consumption.
Researchers adjusted for
clinical variables and sociodemographic data, and found that moderate, heavy
drinkers, and former heavy drinkers were at a greater risk for having hyaline
arteriolosclerosis compared to participants who never had drunk alcohol.
Heavy drinkers were specifically at 133% increased
risk for hyaline arteriolosclerosis. Heavy and former heavy drinkers were also
at an increased risk for neurofibrillary tangles, which are related to
Alzheimer’s disease pathology.
Former heavy drinkers also
had lower brain weights. They had slightly higher average clinical dementia
rating scores compared to never-drinkers. In this case, higher scores indicate
worse cognitive function. There was no association between heavy and moderate
drinking and cognitive function.
The findings also indicated
that drinking alcohol did not have an overall or direct effect on people’s
cognitive abilities. Instead, researchers found that hyaline arteriolosclerosis
mediated the association between alcohol consumption and cognitive abilities.
This could indicate that
alcohol affects hyaline arteriolosclerosis, which then may affect aspects of
brain function.
Haris Kamal, MD, a
neurologist at Memorial Hermann, who was not involved in this research, noted
the following about the study findings to Medical News Today:
“The effect of alcohol on the human brain is dependent
on multiple factors such as age, number of years of heavy alcohol use, overall
health, nutritional intake etc. This study demonstrates that moderate to heavy
alcohol use or even a history of prior heavy alcohol use is associated with
more arteriosclerosis in the smallest arteries in the brain; such a progressive
thickening of the arterial walls and increased deposition of neurofibrillary
tangles of tau protein can lead to cognitive impairment including dementia.”
The research
does have some limitations. For one, researchers had to rely on family members
for information such as clinical information and data on participants’ drinking
habits.
It is possible that these
reports from next of kin were inaccurate. They also missed “longitudinal
follow-up data” before participants’ deaths, such as on how long participants
had been consuming alcohol.
Furthermore, this study
focused on people in one country, so data from other countries may also be
useful in drawing stronger conclusions.
The study did find that
heavy drinkers were more likely to die early but had lower frequency of high
blood pressure, neuropathologic lesions, and stroke when researchers did the
univariate analysis. The authors think this could be because of survival bias,
which is linked to lower life expectancy in this demographic.
Researchers also note that
since the study was cross-sectional, it does not show causality. The study’s cross-sectional
nature also did not allow them to look at the long-term effects of components
like heavy drinking.
Moreover, it is possible
that reverse causality is part of the reason for certain results, such as why
they observed cognitive problems in former heavy drinkers.
Finally, researchers did
not examine participants’ vitamin deficiencies, which could have amplified the
observed cognitive decline. Future studies should take vitamin status into
account.
Study author Alberto Justo,
PhD, a researcher at the University of São Paulo Medical School, told MNT that:
“Future research should focus on cohort studies to better understand the causal
relationships between alcohol consumption and brain changes over time. This
research will help clarify how different levels and durations of alcohol intake
affect cognitive health.”
Tony Thrasher,
DO, MBA, CPE, DFAPA, who was not involved in this research, also cautioned
that:
“While there were limitations (well documented)
pertaining to the thoroughness of data collection (from next of kin) and
longitudinal knowledge of said alcohol consumption, the overall numbers are
fairly striking. Past studies have already demonstrated that heavy drinkers die
multiple years earlier when compared to nondrinkers. While still noting
survival bias is present, the study gives hope to those health care providers
who look for data sets to support them during motivational interviewing.”
Heavy drinking causes vascular changes in the brain
So far, the data indicate some very real potential
dangers that alcohol consumption can pose to the brain. Justo noted that:
“Our study found that even moderate alcohol
consumption may lead to vascular changes in the brain, such as hyaline
arteriolosclerosis. We also observed that former heavy drinkers had reduced
brain mass and poorer cognitive abilities. This highlights how alcohol, even in
moderate amounts, can significantly impact brain health. These findings suggest
the need for increased awareness about the risks of alcohol consumption on
brain health, even at moderate levels.”
The findings could be
highly relevant to clinical practice down the road.
“Potential clinical
implications of this study are the finding that heavy alcohol use or a history
of heavy alcohol use can lead to accelerated subcortical disease in the brain
which would manifest as a cognitive impairment,” Kamal.
“Such people over time may
progressively demonstrate paucity/slowness of thought, memory issues, trouble
with executive functioning etc,” he explained, adding that “accumulation of
such small vessel disease in the brain typically can lead to a condition called vascular dementia.”
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