Alcohol use disorders are a major risk factor for the onset of all types of dementia, especially early-onset dementia, according to a French nationwide observational study including over one million adults diagnosed with dementia between 2008-2013, published in The Lancet Public Health journal.
Of the 57000 cases of early-onset dementia (before the age of 65), the majority were either alcohol-related by definition (39%) or had an additional diagnosis of alcohol use disorders (18%).
Previous research has shown mixed results regarding the effect of alcohol on cognitive health, with some studies showing a possible benefit of light to moderate drinking, while others have found detrimental effects of heavy drinking on dementia risk. The World Health Organisation (WHO) defines chronic heavy drinking as consuming more than 60g of pure alcohol a day for men (around 6 or more standard drinks per day on average) and more than 40g per day for women (around 4 or more standard drinks per day).
This study looked specifically at the effect of alcohol use disorders and included people who had been diagnosed with mental and behavioral disorders or chronic diseases that were attributable to the chronic harmful use of alcohol.
As a result of the strong association found in this study, the authors suggest that screening, brief interventions for heavy drinking, and treatment for alcohol use disorders should be implemented to reduce the alcohol-attributable burden of dementia.
“The link between dementia and alcohol use disorders needs further research but is likely a result of alcohol leading to permanent structural and functional brain damage. Alcohol use disorders also increase the risk of high blood pressure, diabetes, stroke, atrial fibrillation, and heart failure, which may, in turn, increase the risk of vascular dementia. Lastly, heavy drinking is associated with tobacco smoking, depression, and low educational attainment, which are also risk factors for dementia.” says lead author Dr. Michaël Schwarzinger, Translational Health Economics Network, France.
The study used data from the French National Hospital Discharge database (Programme de Médicalisation des Systèmes d’Information) which holds details on all hospital admissions, including patient demographics, reasons for a hospital stay, and treatments received.
The study included all patients over the age of 20 who lived in France, who were discharged with alcohol-related brain damage, vascular dementia, or other dementias (including Alzheimer’s disease) between 2008-2013. The authors excluded patients with diseases linked to rare dementias and people with early-life mental health disorders.
Between 2008-2013, 31.6 million people were discharged from the hospital, with more than 1.1 million people diagnosed with dementia and included in the study. One in 20 of these cases were early-onset dementia (5%, 57353 cases).
Over the same time, there were 945512 people diagnosed with alcohol use disorders, with alcohol dependency diagnosed in the majority of cases (86%, 816160/945512).
Around 3% of dementia cases (35034/1109343 cases) were attributable to alcohol-related brain damage, and other alcohol use disorders were recorded in almost 5% of dementia cases (52625/1109343 cases).
However, the prevalence of these conditions increased in early-onset dementia, where 39% (22338/57353 cases) of cases were attributable to alcohol-related brain damage, and 18% (10115/57353 cases) of cases had other alcohol use disorders.
Overall, alcohol use disorders were associated with a three times greater risk of all types of dementia and were the strongest modifiable risk factor for dementia onset. In the cohort study, 6.2% of men discharged from the hospital had alcohol use disorders, compared to 16.5% of men with dementia (1.5% vs 4% for women).
Excluding alcohol-related brain damage, alcohol use disorders were still associated with a two times greater risk of vascular and other dementias (6.2% of men discharged from hospital had alcohol use disorders, compared to 11.2% of men with vascular dementia and 9.8% with other dementia (1.5% vs 3.1% and 2.5% for women).
Alcohol use disorders were also associated with all other independent risk factors for dementia onset, such as tobacco smoking, high blood pressure, diabetes, lower education, depression, and hearing loss among modifiable risk factors. It suggests that alcohol use disorders may contribute in many ways to the risk of dementia.
“Our findings suggest that the burden of dementia attributable to alcohol use disorders is much larger than previously thought, suggesting that heavy drinking should be recognized as a major risk factor for all types of dementia. A variety of measures are needed, such as reducing availability, increasing taxation, and banning advertising and marketing of alcohol, alongside early detection and treatment of alcohol use disorders.” Says Dr. Schwarzinger.
The authors note some limitations, including that there is a risk of individual medical details being misclassified or missing due to the administrative recording of data. In addition, due to stigma, it is likely that alcohol use disorders are underreported and only the most severe cases included as they involved hospitalizations, which could mean that the association is underestimated.
