PEOPLE harmed by excessive alcohol consumption are three times more likely to develop dementia, especially early-onset dementia, according to a major new study.

Researchers who combed through the records of more than a million hospital patients in France found that 57 per cent of those diagnosed with dementia before the age of 65 also had a medical disorder caused by chronic alcohol abuse, such as alcoholic liver disease or Wernicke-Korsakoff syndrome - a vitamin deficiency linked to heavy drinking.

Read more: Boy, nine, treated for alcohol brain damage

Overall, men and women with such as condition were, respectively, 3.36 and 3.34 times more likely to develop dementia during their lifetime than those without.

Writing in the journal, Lancet Public Health, they say their findings indicate that the "burden of dementia attributable to alcohol is much larger than previously thought", and call for earlier detection and treatment of problem drinkers in order to curb the toll of the disease.

The study found that even former alcoholics who had quit booze completely remained at heightened risk of dementia due to the "lifelong brain damage" it caused.

Read more: Dementia deaths in Scotland double in six years 

A comment piece accompanying the main study states: "In our view, this evidence is robust and we should move forward with clear public health messages about the relationship between both alcohol use disorders and alcohol consumption respectively, and dementia...we might want to consider the extent to which the growing prevalence of dementia worldwide might be curbed by reductions in population-level alcohol consumption."

Dr Eric Carlin, director of Scottish Health Action on Alcohol Problems (SHAAP) said the findings would be of huge interest to researchers in Scotland.

He said: "We have highlighted this as an area where we think we need more research and more evidence. We do know that alcohol affects the brain, especially the adolescent brain, and how do we tackle that? We need action on selling cheap alcohol, action on availability, action on marketing and a better range of treatments.

"The findings are not surprising, but if we've got more evidence to support it that's to be welcomed."

Read more: Alcohol deaths spike amid funding cuts for support

It comes amid a steady climb in diagnoses of dementia across Europe, with the number of new cases in Scotland alone predicted to increase to 19,473 by 2020 - up 17 per cent in six years. This will include nearly 650 people in Scotland diagnosed with early-onset dementia before they turn 65.

The World Health Organisation defines chronic heavy drinking as around two and half glasses of wine a day in women or four pints of beer a day in men. Despite Britain's reputation for binge drinking, average alcohol consumption in France is slightly higher than the UK at 12.2 litres per person per year, compared to 11.6 litres a year for Brits. Prevalence of dementia is also higher in France than the UK, at 1.85 per cent compared to 1.65 per cent.

However, the Lancet study does not link an increased risk of dementia to a specific danger threshold of alcohol consumption.

Instead, the authors examined data on 1.1 million patients discharged from city hospitals across France between 2008 and 2013 with a diagnosis of dementia. Of these patients, 57,353 were diagnosed with early-onset dementia and 56.5 per cent of these individuals had a health problem caused by chronic harmful alcohol consumption. These included mental or behavioural disorders, alcoholic liver disease, Wernicke-Korsakoff syndrome, epilepsy, and head injuries.

Lead author Dr Michaël Schwarzinger said that the correlation is "likely a result of alcohol leading to permanent structural and functional brain damage", but stressed that further research is needed since heavy drinking is also associated with diabetes, high blood pressure, stroke, smoking and depression which are all risk factors for dementia.

The authors added that the study also underlined the need for "alcohol policy measures, such as a reduction of availability, increase of taxation, and a ban on advertising and marketing".

Scotland will become the first country in the world to introduce minimum unit pricing of alcohol from May 1 this year.

Jim Pearson, director of policy and research for charity Alzheimer Scotland, said: “Alzheimer Scotland welcome this important study which highlights the potential of heavy drinking as a major risk factor for dementia.

“This adds to the increasing body of evidence that changes to our lifestyles can potentially reduce the risks of developing dementia. These include keeping physically, mentally and socially active and maintaining a healthy diet.

“Overall, we need much more research into the causes of dementia, treatments and supports that allow people to live well with dementia, as well as seeking to prevent and even cure of the condition.

"If you have any questions about dementia call Alzheimer Scotland’s 24 Hour Helpline on 0808 808 3000."