The study tracked the drinking habits of 9,000 London civil servants between the ages of 35 and 55 from 1985 to 1993.

They were then monitored for, on average, another 23 years. In total there were 397 cases of dementia identified through hospital, mental health services and mortality records.

Published in the British Medical Journal (BMJ) the data showed abstinence in midlife was associated with a 45% higher risk of dementia compared with people who consumed between one and 14 units of alcohol per week.