Scientists have long speculated that chronically unhealthy lifestyles lay waste to the brain.
Yesterday, research presented at the Alzheimer’s Association International Conference showed those who consume large amounts of sugar increase risk by a third.
Researchers obtained information on added sugar consumption from soft drinks (excluding low calorie or diet drinks), fruit drinks and food from a questionnaire.
Over seven years there were 429 cases of Alzheimer’s in the 2,226 cases.
Those having 30.3 grams of added sugar each day saw their risk increase by 33 per cent compared with those consuming the lowest amount, which was 5.8 grams.
There are 35g of sugar in a standard 330ml can of Coca-Cola Classic, or about seven teaspoons.
Raised blood sugar is known to trigger diabetes but the association with dementia remains unclear.
Both Alzheimer’s and diabetes involve changes in glucose metabolism and scientists think alterations in sufferers’ brains could be caused by excess glucose, one of the hallmarks of diabetes.
Dr Doug Brown, at Alzheimer’s Society, said: “Too much sugar is linked to Type 2 diabetes and our previous research has identified Type 2 as a risk factor for dementia.
“This study backs up this evidence, suggesting excess sugar may increase our risk of Alzheimer’s, and all types of sugar – from fruit juice to lemonade – have the same impact.”