New guidelines released by the world’s leading health authority on reducing the risk of cognitive decline assert that almost half of dementia cases are preventable.

The World Health Organisation (WHO) released the new evidence-based recommendations on Wednesday, aiming to help prevent or delay the onset of dementia in a person’s life.

WHO estimated about 57 million people around the world have dementia, with some 10 million more diagnosed each year, costing the global economy an estimated $US1.3 trillion annually.

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There are nearly half a million Australians living with dementia, with Alzheimer’s disease the most common form of dementia, estimated to account for 60 to 70 per cent of cases globally.

“We know more today than ever before about what drives dementia risk, and these guidelines translate that knowledge into action,” WHO Director-General Dr Tedros Adhanom Ghebreyesus said.

“Countries now have clear, evidence-based recommendations they can put into practice immediately to protect people’s cognitive health.”

WHO said about 45 per cent of dementia cases have “modifiable risk factors” making the disease preventable.

Social isolation has been highlighted as a preventable risk factor for dementia. Credit: AAP

Risk factors identified

Modifiable risk factors have been identified as tobacco and alcohol use, social isolation, physical inactivity, air pollution and noncommunicable diseases (NCDs) including high blood pressure and diabetes.

“These guidelines are the culmination of a systematic and wide-ranging review of the evidence we now have about the efficacy of a range of interventions that can reduce dementia risk,” said Professor Kaarin Anstey, director of the UNSW Ageing Futures Institute and the only Australian researcher on WHO’s Guideline Development Group that produced the new guidance.

“These recommendations offer real-life actions that will reduce dementia risk and promote brain health.

“They’re both practical and evidence-based but require the buy-in of governments and public health systems to be truly effective.”

Leading a healthier lifestyle and minimising risks of noncommunicable diseases such as high blood pressure and diabetes has been recommended in preventing dementia. Credit: Supplied

WHO’s guidelines recommend several healthy behaviours and lifestyle interventions to reduce dementia risk, including “cognitive training and cognitive stimulation and engagement in social activities”.

The organisation also noted that intervention to reduce the risk of cognitive decline does not include vitamin supplements, due to a lack of evidence of any potential benefits.

“The guidelines reflect our understanding of dementia prevention across the life course, and the fact that brain health is something we need to consider as a lifelong commitment,” Anstey said.

“We need to underline the message that many cases of dementia may be prevented, and these guidelines are a vital step forward in reinforcing that.”