The evidence for the harmful effects of alcohol on brain health is compelling, but now experts have pin-pointed three key time periods in life when the effects of alcohol are likely to be at their greatest.
Writing for The BMJ, UNSW Scientia Fellow at the Centre for Healthy Brain Ageing (CHeBA), Dr Louise Mewton, says evidence suggests three periods of dynamic brain changes that may be particularly sensitive to the harmful effects of alcohol: gestation (from conception to birth), later adolescence (15-19 years), and older adulthood (over 65 years).
The editorial, which has co-authors from the University of Sydney and Kings College London, highlights alcohol use as being the strongest modifiable risk factor for dementia when compared with other established risk factors, and the need to develop an integrated approach to harm reduction from alcohol across the lifespan.
There is an undeniable cumulative effect of alcohol use on cognitive health across the lifespan.
UNSW Scientia Fellow at CHeBA, Dr Louise Mewton
Globally, around 10% of pregnant women consume alcohol, with the rates considerably higher in European countries than the global average.
Heavy alcohol use during pregnancy can cause foetal alcohol spectrum disorder, associated with widespread reductions in brain volume and cognitive impairment. But data suggest that even low or moderate alcohol consumption during pregnancy is significant associated with poorer psychological and behavioural outcomes in offspring.
In terms of adolescence, more than 20% of 15-19 year olds in European and other high income countries report at least occasional binge drinking (defined as 60 g of ethanol on a single occasion).
Dr Louise Mewton
Studies indicate that the transition to binge drinking in adolescence is associated with reduced brain volume, poorer white matter development (critical for efficient brain functioning), and small to moderate deficits in a range of cognitive functions.
And in older people, alcohol use disorders were recently shown to be one of the strongest modifiable risk factors for all types of dementia (particularly early onset) compared with other established risk factors such as high blood pressure and smoking.
Although alcohol use disorders are relatively rare in older adults, Dr Mewton explains that even moderate drinking has been shown to be linked to a small but significant loss of brain volume in midlife, although further studies are needed to test whether these structural changes translate into functional impairment.
Furthermore, demographic trends may compound the effect of alcohol use on brain health. For example, women are now just as likely as men to drink alcohol and experience alcohol related harms, and global consumption is forecast to rise further in the next decade.
The effects of the Covid-19 pandemic on alcohol use and related harms are unclear, but alcohol use increased in the long term after other major public health crises, the authors add.
As such, they call for an integrated approach to harm reduction at all ages.
“The maintenance of brain health is central to health and wellbeing across the lifespan,” says Dr Mewton.
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.
Dr Louise Mewton
“The formulation of such health interventions has promise for increasing longevity and quality of life including preventing foetal alcohol spectrum disorders, neurocognitive disorders in teenagers, and dementia in later life,” says Dr Mewton.