Restricted eating hours may cut dementia risk, researchers say
Study finds that women who avoided eating four hours before going to bed improved their memory and problem-solving skills
Eating for just a nine-hour window and having no food for four hours before going to bed could reduce the risk of dementia, a new study has suggested.
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A small trial of overweight or obese women showed an improvement in memory and problem-solving skills among those limiting the amount of time they could eat, compared with those who spread out their meals over a longer period.
Researchers at Rutgers University in New Jersey studied 47 women, aged 50 to 79, who were on a diet. If confirmed in larger studies, it could help people protect their cognitive abilities.
The women were asked to reduce their calorie intake by 500 calories per day, with half also asked to only eat between 10 am and 6 pm each day, to have a longer period of fasting.
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After six months, both groups had similar weight loss of about 7kg (15lbs), but those who had spent longer periods not eating performed better on spatial planning and problem-solving tests.
They also seemed to make fewer errors on memory and learning tests, although on multitasking and reaction time tests performance was the same.
The report authors say it suggests it “may be possible to reduce your risk of dementia by eating during fewer hours of the day”.
The findings are being presented at Nutrition 2026, the annual meeting of the American Society for Nutrition in Maryland.
Professor Sue Shapses, a nutritional scientist at Rutgers University and the study’s principal investigator, pointed out that losing weight alone can help slow cognitive decline in older age, but there may be “modest...additional benefits” for people who do not eat outside an eight- to nine-hour window, and stop eating four hours before going to sleep.
The researchers now plan to investigate other possible benefits of intermittent fasting, such as improving brain resilience, including how it affects circadian rhythm, inflammation and metabolic health.
Dementia is the leading cause of death in the UK and the seventh worldwide, with nearly 2 million deaths globally per year, according to the World Health Organization. It also affects more women than men.
Alzheimer's disease is the most common form of dementia and may contribute to 60–70% of cases. Last week, it was announced that a new Alzheimer's drug, Trontinemab, will be offered to 1,600 people with no memory loss who are at a high risk of the disease.
The Alzheimer's Society say obesity in middle age can raise the risk of dementia in later life by 30%. It estimates that about a million people in the UK have dementia, a number likely to rise to 1.4 million by 2040.
Experts believe, however, that nearly half of cases could be prevented or delayed through lifestyle changes.
Earlier this month, a study published in The Lancet found that a structured programme of regular exercise and a brain-healthy diet could improve memory and thinking in older people at risk of dementia.