The relationship between alcohol and dementia
prevention has been widely studied, but most studies
have focused on the potential for modest alcohol
consumption to reduce the risk of dementia.
Published studies are interesting and pose questions
such as whether modest consumption of red wine could
be protective as part of a Mediterranean diet.
However, the potential for substantial alcohol
consumption, equivalent to 7–8 units a day for men
and 5 units a day for women in most studies, to be a
substantial risk factor for dementia is often
The effect of alcohol use disorders specifically on
dementia has received very little attention,
although an association with an increased risk of
cognitive decline has been suggested.
In The Lancet Public Health, Michaël Schwarzinger
and colleagues present their findings from a large
retrospective study of data from over 31 million
people aged at least 20 years from the French
National Hospital Discharge database, including over
1 million people with an International
Classification of Diseases, tenth revision (ICD-10)
diagnosis of some form of dementia.
Alcohol-related brain damage or alcohol use
disorders based on ICD-10 codes were recorded in
more than 85?000 of those who developed dementia,
with a hazard ratio greater than 3 for the
association between alcohol use disorders and
dementia for both sexes.
The importance of alcohol use disorders was
particularly striking in people with early-onset
dementia: 57% of people with a diagnosis of
early-onset dementia also had an alcohol use
Schwarzinger and colleagues modelled the importance
of alcohol use disorders and suggested their effect
might be greater than that of recognised risk
factors such as smoking, depression, and
Their study is immensely important and highlights
the potential of alcohol use disorders, and possibly
alcohol consumption, as modifiable risk factors for
Schwarzinger and colleagues discuss potential
mechanisms, including a direct neurotoxic effect of
ethanol and metabolites; thiamine deficiency;
consequences of heavy alcohol use such as hepatic
encephalopathy, epilepsy, and head injury; and
increased occurrence of comorbid medical and
lifestyle risk factors for dementia.
An important caveat is that people with Down's
syndrome and other learning disabilities—a group at
major risk of early-onset dementias—were excluded
from the study.
Many reports addressing dementia risk, such as the
Lancet Commission on dementia prevention,
intervention, and care, have not highlighted alcohol
use disorders as a substantial attributable risk
factor for dementia.
The focus on the potential protective effects of
modest alcohol use has probably complicated the
analysis and interpretation of previous findings,
and the potential importance and effect of heavy
alcohol use as a modifiable risk factor for dementia
has probably been overlooked.
Several issues still need to be addressed.
One is the relationship between alcohol use
disorders and related comorbidities.
Alcohol use disorders are probably associated with
poor diet and lifestyle, smoking, cardiovascular
comorbidity, lower adherence to medical treatments,
depression, and potentially social isolation.
Schwarzinger and colleagues used a crude, area-based
measure of socioeconomic status, and exploration of
this aspect of the relationship between alcohol use
disorders and dementia in more detail will be
Understanding the significance of these risk
factors, and the pathways of risk impact in people
with alcohol use disorders, will help researchers to
model the attributable risk more accurately and to
develop better prevention strategies for people with
alcohol use disorders.
Additional questions relate to the threshold of
alcohol consumption and potential cross-cultural
In the study by Schwarzinger and colleagues, the
focus was on a diagnosis of alcohol use disorders
rather than a threshold of alcohol consumption:
individuals with alcohol use disorders had this
information captured in a hospital database, having
been identified as having problems related to their
Alcohol use disorders and alcohol consumption
volumes are related but distinct, and work is needed
to clarify whether there is an association of
similar magnitude between alcohol consumption
volumes and dementia or whether associated problems
and medical and psychiatric comorbidity drive the
A related question is whether the importance of
alcohol consumption and alcohol use disorders as a
risk factor varies depending on national mean
alcohol consumption; for example, France consumes
12·2 L per person per year, much higher than Italy
(6·7 L per person per year) and India (4·3 L per
person per year).
Although many questions remain, several can be
answered using existing data, which would provide an
opportunity to refine our understanding of the
pathways of modifiable risk and develop optimal
This evidence is robust.
For more information
Alcohol and dementia: a complex relationship with
potential for dementia prevention
Contribution of alcohol use disorders to the burden
of dementia in France 2008–13: a nationwide
retrospective cohort study
Translational Health Economics Network, Paris,
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Unité mixte de recherche 1137 - Infection,
Antimicrobiens, Modélisation, Evolution