The research, led by the University of Wolverhampton, examined 38,219 participants and 4,479 dementia cases worldwide, through a systematic search and review.
Studies from younger and middle age populations have demonstrated excessive body weight increases the risk of incident dementia. But the contrary has been the case for most reported findings of overweight and obesity in older age, following a paradox on their beneficial impacts on reducing mortality.
However, the researchers believe it is likely that there are indirect effects of being different categorised weight in older age via other chronic conditions, which reduce weight. From their systematic data analysis, the researchers have identified that overweight and obesity in older age are not protective factors for dementia at least, and may increase the risk of dementia in the later life, where most of dementia take place.
Professor Ruoling Chen, Professor of Public Health and Medical Statistics and Lead of Global Health and Epidemiology research at the University of Wolverhampton, said: “Our work has implications for policy making and public health practice.
“There is no evidence to support recommendation of increasing body weight in older age for the purpose of preventing increased risk of dementia. However, we should pay more attention to older adults who lose weight, probably due to chronic diseases, for developing dementia. Controlling bodyweight to be within normal range in older age may prevent dementia.
“As recommended by the current guidelines, maintaining normal body weight from young to older ages is necessary, and public health prevention and intervention strategies for tackling overweight and obesity should be sustained in older people.”
The full report, Impacts of Overweight and Obesity in Older Age on the Risk of Dementia: A Systematic Literature Review and a Meta-Analysis, has been published in The Journal of Alzheimer’s Disease.
‘Incident’ dementia refers to newly diagnosed dementia cases in older age after exposure to certain risk factors and most of these are yet to be fully understood.