Confining mealtimes and snacks to a nine-hour window and avoiding food for four hours before bed may help stave off cognitive decline in older age, researchers say.

A pilot study of older women living with overweight or obesity found hints of improvement in mental skills among those who ate within the restricted period compared with those who spread their meals over a longer time.

The finding is preliminary given the numbers in the trial, but if confirmed in larger studies, the work suggests people could help to protect their cognitive abilities by eating within a relatively narrow window and not eating late into the night.

Losing weight alone can help slow cognitive decline in older age, said Prof Sue Shapses, a nutritional scientist at Rutgers University in New Jersey, US, but there may be “additional benefits” for people who do not eat outside an eight to nine-hour window, and stop eating four hours before going to sleep.

Dementia is the leading cause of death in the UK and the seventh worldwide, leading to nearly 2 million deaths globally each year. Some risk factors are unavoidable, such as age and genetics, but experts believe nearly half of cases could be prevented or delayed through changes to lifestyle. Obesity in middle age can raise the risk of dementia in later life by 30%.