Dementia risk rises with any amount of alcohol use, new study suggests

Robby Berman

• There is no level of alcohol consumption that does not increase the risk of dementia among drinkers, according to a new study.
• Using statistical methods based on genetic analyses, the authors of the study found that alcohol heightened dementia risk in proportion to the amount of alcohol consumed.
• This study contradicts earlier research that suggested light to moderate drinking may protect against dementia.

There is no level of alcohol consumption that is not associated with a higher risk of dementia, suggests a new study, contrary to previous findings.

The study, which appears in eClinicalMedicine, concludes there is a linear relationship between the amount of alcohol one consumes and the risk of developing dementia.

Earlier research suggested a protective effect for lower and moderate levels of drinking, but the new study finds that this was likely the result of something they refer to as “abstainer bias.”

Putting one question to rest: Is moderate drinking safe for brain health?

Experts have understood for some time that heavy drinking is associated with dementia. However, the effects of light and moderate drinking have remained an area of debate.

In their attempt to clarify the relationship between light and moderate alcohol consumption and dementia, the authors of the study analyzed data from the UK Biobank for 313,958 white, British drinkers.

Participants were free of dementia during initial data collection during 2006–2010. During this time, individuals self-reported their drinking habits, and provided the UK Biobank genetic information.

Participants were followed until 2021, during which time any diagnoses of dementia were recorded. The researchers looked at the data from two perspectives.

For the first, using the self-reported alcohol consumption information, they employed a conventional multivariable Cox analysis. This is a statistical technique often used to assess the relationship between a risk factor and health outcome over time.

This analysis produced the classic “j-curve” graph that implied a protective effect for moderate drinking. This means the graph curve drops down initially, then goes up.

The second perspective involved looking at participants’ genetic data, since the amount of alcohol one consumes can be accurately predicted according to the presence of certain single nucleotide polymorphisms (SNPs) — a type of genetic variation — in a person’s genome. The researchers targeted 95 SNPs that are linked to alcohol consumption but not to smoking.

For these data, they used nonlinear and linear Mendelian randomization analyses, research methods used to provide evidence for causal relationships between risk factors and health outcomes.

Both of these analyses suggested a linear relationship between alcohol consumption and dementia risk, indicating that there is no safe level of alcohol consumption when it comes to dementia risk.

Why does alcohol affect dementia risk?

Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the study, explained for Medical News Today that: “Alcohol is a central nervous system depressant drug which causes brain atrophy. Patients with dementia have baseline suppressed nervous system function with atrophy.”

Ozan Toy, MD, MPH, of Telapsychiatry — also not involved in the study — put the relationship in more mechanistic terms, noting that “alcohol is a known neurotoxin.”

He elaborated that “Alcohol can negatively impact the brain’s memory center known as the hippocampus by causing cell atrophy and by inhibiting the growth of new neurons via a process called neurogenesis. We also know that chronic alcohol use can lead to depletion of an important B-vitamin, thiamine, which is also really important for memory and cognition.”

“Common sense,” said Segil, “dictates that giving a patient with slow brain function a substance that slows brain function down more is going to worsen dementia.”

Does alcohol offer any health benefits?

“For many years,” said Toy, “it used to be believed that moderate alcohol intake could be beneficial for heart health, but recent research has debunked this. There is no good reason to drink alcohol for health reasons.”

Segil agreed with the study’s conclusion that there is no safe level of alcohol consumption.

“Alcohol use can cause seizures or electrical problems in the brain, causing it to short-circuit. Alcohol use can cause neuropathies or fraying of people’s nerves in their hands and feet, causing burning pains and numbness,” he told us.

Segil acknowledged that there was still some debate as to whether light alcohol consumption has some health benefits but stressed that there were no brain health benefits to any alcohol consumption, even in small amounts.

What is ‘abstainer bias’ in alcohol use studies?

The authors of the new study say that a factor in previous research and the j-shaped curve is “abstainer bias.”

Toy explained that “‘abstainer bias’ refers to the inclusion of former drinkers who may have stopped due to health issues in the non-drinker category, as controls.”

“These abstainers have worse health than light drinkers but end up in the control group, which makes alcohol use appear to be healthier than it is,” said Toy.

Alcohol only one factor in dementia risk

While cutting down or stopping alcohol use entirely is one important step in protecting brain health, the experts that MNT spoke to noted that there are many other factors that play a role in dementia risk.

“Age, cardiometabolic disease, smoking, education, and socioeconomic factors likely have more substantial, cumulative effects on dementia risk than alcohol,” said Toy.

“Addressing alcohol consumption, though, offers an important avenue for prevention and should be addressed in any patients at risk for developing dementia,” he added.

Drinking can cause memory loss on its own, independent of a person’s cardiac health, smoking status, or age, said Segil. He noted that he has treated patients whose apparent dementia and memory loss have been resolved by convincing them to stop drinking.

Segil also pointed out that “alcohol use is a frequent medical comorbidity in many neurological diseases, including memory loss, seizures, neuropathies, and traumatic brain injuries.”

“Alcohol use,” emphasized Segil, “is not a ‘rich person’ or ‘poor person’ disease, and afflicts all, independent of their social economic status.”