Taking better care of ourselves could be the best long-term strategy to tackling the growing problem of dementia, according to a new report.

Research by the World Health Organisation (WHO) found dementia affects 50 million people worldwide, costs $818bn (£632bn) annually to treat, and diagnoses are likely to triple by 2050.

In a bid to tackle dementia and general cognitive decline, WHO has set out guidelines linked to overall health and wellbeing.

A huge review of existing evidence found age was the strongest risk factor, but dementia was not an inevitable consequence of ageing. It found lifestyle factors such as physical inactivity, smoking, unhealthy diet and excessive alcohol consumption significantly increased the threat of the disease.

Medical conditions such as diabetes, high blood pressure, high cholesterol, obesity and depression also played a role in cognitive decline and the development of dementia.

A review of previous studies also identified that social isolation, cognitive inactivity and hearing loss was linked to the condition.

The guidelines look at the level of risk posed by 12 possible contributory factors, and also the potential benefit in treating them.

While some factors indicated a strong link with dementia, for example depression or hearing loss, there was insufficient evidence to prove that treatment would prevent or slow the disease.

In these cases, the authors recommended treatment based on existing WHO guidelines to improve the quality of life of the individual.

A healthy diet was also linked to better cognitive health, with a strict adherence to the Mediterranean diet shown to have the strongest link.

But there was no apparent positive relationship between common supplements and a reduced risk of dementia and in some cases, such as protein supplements, they can have negative side-effects.

The report’s authors said: “The vision of the action plan is a world in which dementia is prevented and people with dementia and their carers live well and receive the care and support they need to fulfil their potential with dignity, respect, autonomy and equality.”

Robert Howard, professor of old age psychiatry at University College London, said: “The guidelines are based on a comprehensive and carefully conducted review of the published literature and are sensible but unsurprising.

“Keep on doing the things that we know benefit overall physical and mental health, smoking cessation, reduce harmful alcohol drinking, treat hypertension, eat a healthy balanced diet and lose weight if you are obese, but understand that the evidence that these steps will reduce dementia risk is not strong.

“Like many colleagues, I already tell my patients that what is good for their hearts is probably good for their brains.”

He added that the study highlighted the lack of comprehensive evidence and should be “a call to arms” for investment in thorough dementia prevention trials.

Prof Tom Dening, director of the centre for old age and dementia at the University of Nottingham’s Institute of Mental Health, pointed out that nearly all the strategies to minimise the risk of dementia favour the wealthy.

“Like most of the research on dementia risk factors, it is difficult to see clearly the effects of social inequality, but nearly everything that is modifiable tends to favour people in better socioeconomic circumstances: diet, access to facilities for physical activity, social interactions,” he said.

He added: “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.”