Excessive alcohol intake could lead to dementia

According to one of the largest studies to date, heavy drinkers are putting themselves at increased risk of developing dementia, a progressive brain disease that generally begins with mild memory loss. Heavy drinkers are especially vulnerable to early-onset forms of the disease.

The study, published in the journal The Lancet Public Health, looked at hospital records of more than a million people diagnosed with dementia between 2008 and 2013. The researchers looked for known dementia risk factors, such as tobacco smoking, high blood pressure, type 2 diabetes, lower education, and hearing loss as well as severe cases of alcohol use disorder (people who drink enough to end up in hospital).

Of the 57,000 people diagnosed with early-onset dementia before the age of 65, almost 60 percent were related to chronic heavy drinking, which is defined by the World Health Organisation as consuming more than four to five standard drinks on average per day for men and about three standard drinks per day for women.

“We hypothesised that alcohol would play some role, but I don’t think anyone expected the size of the effect to be so large,” says lead author Dr Jürgen Rehm, director of the University of Toronto’s Centre for Addiction and Mental Health and the Institute for Mental Health Policy Research, to Time.

While some research has suggested that a drink or two a day may have a protective effect on cognitive health, the findings concluded that alcohol use disorders were the biggest preventable risk factor for all types of dementia, including Alzheimer’s disease, for both men and women, across all age groups, compared to other risk factors.

"The findings indicate that heavy drinking and alcohol use disorders are the most important risk factors for dementia and especially important for those types of dementia which start before age 65 and which lead to premature deaths," said Dr Rehm to Science Daily.

She notes that alcohol use disorders can also shorten life expectancy by more than 20 years, on average, with the leading cause of death in this group being dementia.

Dr Christopher Soosay, Consultant Psychiatrist at Dementia Specialists LLP, London, who was not part of the study, explained to Global Health and Travel that “alcohol consumption in excess not only has a direct neurotoxic effect but also indirectly affects brain health by compromising physical and cardiovascular health, which increases the risk of dementia. Intoxication leading to falls, and head injury can increase the risk of brain injury, which increases the risk of developing dementia as well.”

He said that although the study only looked at the people who had been admitted to hospital due to chronic heavy drinking, those who drink excessively but manage to avoid hospitalisation were also at risk of developing slow but incremental damage to the brain over time.

Based on the findings, the authors suggested that “alcohol-induced brain damage and dementia are preventable, and known-effective preventive and policy measures can make a dent into premature dementia deaths.” This includes implementing screening, brief interventions for heavy drinking, and treatment for alcohol use disorders.

 “Although the general public is aware that excessive alcohol consumption harms physical health by damaging vital organs like the heart and liver, many do not realise the damaging effects it can have on the brain increasing the risk of dementia,” said Dr Soosay. “We need a better understanding of the threshold volume of alcohol consumed and drinking behavior required to cause brain damage so that we can provide specific advice to alcohol consumers who may not currently meet the criteria of an alcohol use disorder.”

Dr Rehm believes that reducing alcohol consumption should be included in the nine lifestyle changes that could reduce the risk of dementia. These currently are: providing the public with better education, encouraging physical activity, increasing social interaction, eliminating cigarette smoking, treating hypertension and diabetes, reducing obesity, managing hearing impairment, and treating depression.

“They don’t need to become abstainers or teetotallers, but in many cases, they could reduce their drinking to safer levels,” she said to Time.

This story was originally published in the Global Health and Travel issue of August-September 2018.