Drinking three to five coffees daily in middle age cuts the risk of developing the disease in old age by two-thirds, a study has found.
Other studies have hinted that caffeine can protect against dementia, but the latest research stands out because it charted people's consumption over the decades before dementia appeared rather than relying on them to remember their intake.
Dr Susanne Sorensen, of the Alzheimer's Society, said: 'For years we've treated coffee as nothing more than a pleasant pick-me-up.This is exciting as it indicates drinking coffee in midlife can actually reduce your risk.'
Swedish and Finnish researchers questioned 1,500 middle-aged men and women about their tea and coffee drinking. Twenty-one years later, there were 61 dementia cases in the group.