04 Dec 2020
Megan Brooks
There is "compelling" evidence of the harmful effects of alcohol on the brain. The greatest risk occurs during three periods of life that are marked by dynamic brain changes, say researchers from Australia and the United Kingdom.
The three periods are
Gestation (conception to birth), which is characterized by extensive production, migration, and differentiation of neurons, as well as substantial apoptosis;
Later adolescence (age 15 to 19 years), a period marked by synaptic pruning and increased axonal myelination; and
Older adulthood (age 65 and beyond), a period associated with brain atrophy. Changes accelerate after age 65, largely driven by decreases in neuron size and reductions in the number of dendritic spines and synapses.
These changes in neurocircuitry could increase sensitivity to the neurotoxic effects of alcohol, Louise Mewton, PhD, Center for Healthy Brain Aging, University of New South Wales, Sydney, Australia, and colleagues say.
"A life course perspective on brain health supports the formulation of policy and public health interventions to reduce alcohol use and misuse at all ages," they write in an editorial published online December 4 in The BMJ.
Worrisome Trends
Research has shown that globally, about 10% of pregnant women drink alcohol. In European countries, the rates are much higher than the global average.
Heavy drinking during gestation can cause fetal alcohol spectrum disorder, which is associated with widespread reductions in brain volume and cognitive impairment.
Even low or moderate alcohol consumption during pregnancy is significantly associated with poorer psychological and behavioral outcomes in children, the investigators note.
In adolescence, more than 20% of 15- to 19-year-olds in European and other high-income countries report at least occasional binge drinking, which is linked to reduced brain volume, poorer white matter development, and deficits in a range of cognitive functions, they add.
In a recent study of older adults, alcohol use disorders emerged as one of the strongest modifiable risk factors for dementia (particularly early-onset dementia) compared with other established risk factors, such as high blood pressure and smoking.
Alcohol use disorders are relatively rare in older adults, but even moderate drinking during midlife has been linked to "small but significant" brain volume loss, the authors say.
Mewton and colleagues say demographic trends may compound the effect of alcohol use on brain health.
They note that women are now just as likely as men to drink alcohol and suffer alcohol-related problems. Global consumption is forecast to increase further in the next decade.
Although the effects of the COVID-19 pandemic on alcohol intake and related harms remain unclear, alcohol use has increased in the long term after other major public health crises, they add.
Given the data, Mewton and colleagues call for "an integrated approach" to reducing the harms of alcohol intake at all ages.
"Population based interventions such as guidelines on low risk drinking, alcohol pricing policies, and lower drink driving limits need to be accompanied by the development of training and care pathways that consider the human brain at risk throughout life," they conclude.
The authors have disclosed no relevant financial relationships.
BMJ. Published online December 4, 2020. Editorial
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