Global cost of dementia now £388bn say experts

This includes the cost of social care, unpaid care by relatives and medical bills and the figure is expected to rise rapidly in the coming years – but governments are woefully unprepared to meet the challenge, said the World Alzheimer Report 2010.

Experts at the Karolinska Institute in Sweden and King's College London examined the cost of dementia care and found that, if it was a country, it would be the world's 18th biggest economy.

And if it was a company, it would be the world's biggest by annual revenue, way above Wal-Mart ($414bn or 265.6bn) and Exxon Mobil ($311bn or 200bn).

Campaigners have already warned that the costs of caring for people with dementia are on the rise, mostly due to people living longer. An estimated 35.6 million people currently have dementia worldwide, increasing to 65.7 million by 2030 and 115.4 million by 2050.

Worldwide, there could be an 85 per cent increase by 2030.

In the UK, the Alzheimer's Society has estimated dementia costs the country 20bn a year.

The report was issued to coincide with World Alzheimer's Day and was commissioned by Alzheimer's Disease International (ADI).

Dr Daisy Acosta, chair of ADI, said: "This is a wake-up call that Alzheimer's disease and other dementias are the single most significant health and social crisis of the 21st century. World governments are woefully unprepared for the social and economic disruptions this disease will cause."

The study recommends all governments formulate long-term plans and praises work already ongoing in France, Australia and England. But it warns research must also be properly funded – currently it lags way behind other conditions like heart disease and cancer.