Obesity, which is associated with cardiovascular problems, may also be linked with dementia in later life.
A study 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 onwards).
Symptoms of dementia include memory loss, forgetting simple words, poor judgement and inability to carry out daily chores.
The study was conducted by Kaarin Anstey from the Centre for Mental Health Research at the Australian National University.
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, according to a Australian National University statement.
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 added.