Dementia and obesity are two of Australia's biggest public health problems and the relationship between them is now one step closer to being understood, thanks to new research from The Australian National University.
The review study, conducted by Professor Kaarin Anstey from the Centre for Mental Health Research in the ANU College of Medicine, Biology and Environment, found that people who are very underweight, overweight or obese in mid-life (40-60 years) have an increased risk of developing dementia in late-life (60 upwards).
The study synthesised data from high-quality, long-term studies that followed over 25 000 people to see if bodyweight is a risk factor for dementia.
Professor Anstey said the review produced evidence that a higher body-mass-index (BMI) is associated with chronic diseases that increase the risk of dementia.
"We found that, in mid-life, being overweight does in fact increase the risk of Alzheimer's Disease. This risk is even greater for those who fall into the category of obese.
"This evidence suggests that, while the hormones present in body-fat were previously believed to protect cognitive function, excess fat in middle age is in fact extremely harmful," she said.
Professor Anstey added that the findings have significant policy implications.
"Practitioners and policy-makers should be concerned, not just with the short-term effects obesity has on quality of life, but also about the long-term effects that obesity can have on the aging process.
"Without a reduction in the numbers of overweight and obese middle-aged adults, our results suggest that we can expect to see an increase in dementia over the coming years.
"Reducing the impact of obesity on the prevalence and incidence of dementia should be a priority for governments, health providers and the general public," she said.