There's no effective treatment for dementia, which affects 50 million people worldwide, but the World Health Organization says there's much can be done to delay or slow the onset and progression of the disease.
In guidelines released Tuesday, WHO issued its first recommendations to reduce the risk of dementia globally. They include regular physical exercise, not using tobacco, drinking less alcohol, maintaining healthy blood pressure and eating a healthy diet -- particularly a Mediterranean one.
The international health body also warned against taking dietary supplements such as vitamins B and E in an effort to combat cognitive decline and dementia.
"While some people are unlucky and inherit a combination of genes that makes it highly likely they will develop dementia, many people have the opportunity to substantially reduce their risk by living a healthy lifestyle," professor Tara Spires-Jones, UK Dementia Research Institute program lead and deputy director of the Centre for Discovery Brain Sciences at the University of Edinburgh, told the Science Media Center.
"The WHO has looked at the available evidence and made recommendations that some lifestyle changes, in particular increasing exercise before any cognitive symptoms are present, can reduce dementia risk," she added.
"Other recommendations have a less strong evidence base but may have evidence that they do not increase risk or harm and can therefore be recommended safely, although their impact on risk is less certain."
WHO said there are 10 million new cases of dementia every year, and this figure is set to triple by 2050. The disease is a major cause of disability and dependency among older people and "can devastate the lives of affected individuals, their carers and families," the organization said.
The disease also exacts a heavy economic toll, with the cost of caring for people with dementia estimated to rise to $2 trillion annually by 2030, according to WHO.
What will and won't help
The 78-page report outlined what WHO believes will -- and won't -- help reduce the risk of dementia, which has been described by campaigners as the biggest health challenge of our generation.
It recommended physical activity, stopping smoking, consuming less alcohol and a healthy, balanced diet. In particular, it says that committing to a Mediterranean diet (simple plant-based cooking, little meat and a heavy emphasis on olive oil) could help.
"The Mediterranean diet is the most extensively studied dietary approach, in general as well as in relation to cognitive function," the report said. "Several systematic reviews of observational studies have concluded that high adherence to the Mediterranean diet is associated with decreased risk of mild cognitive impairment and Alzheimer's Disease, but modest adherence is not."
The report recommended proper management of weight, hypertension, diabetes and dyslipidemia -- unhealthy or unbalanced cholesterol levels -- as measures that could potentially reduce the risk of dementia and cognitive decline.
Although the report stressed that social participation and social support are strongly connected to good health and individual well-being, it said there was insufficient evidence linking social activity with a reduced of risk of dementia.
Similarly, it said cognitive training could be offered to older adults but the evidence linking it to a lower risk of dementia was "very low to low."
The report also warned against using supplements such as B vitamins, antioxidants, omega-3 and ginkgo.
"The negative recommendation, advocating that people do not use vitamin or dietary supplements (unless they are needed for a clinical problem) is welcome, and it is to be hoped that it saves lots of people from wasting their money," said professor Tom Dening, director of the Centre for Old Age and Dementia, Institute of Mental Health at the University of Nottingham.
Experts said that the advice issued by WHO was comprehensive and sensible, but some cautioned that the evidence that these steps would reduce dementia risk was not always strong.
"Keep on doing the things that we know benefit overall physical and mental health, but understand that the evidence that these steps will reduce dementia risk is not strong," Robert Howard, a professor of old age psychiatry at University College London, told the Science Media Center.
"Like many colleagues, I already tell my patients that what is good for their hearts is probably good for their brains."