The worldwide costs of dementia, eg social care, unpaid support by relatives and medical bills, will exceed 1% of global gross domestic product in 2010 at $604 billion and governments are "woefully unprepared" to deal with the problem.

So claims a report issued by Alzheimer's Disease International and authored by Anders Wimo of the Karolinska Institutet in Stockholm and Martin Prince at King's College London. They claim that it provides "the most current and comprehensive global picture of the economic and social costs of the illness" and makes for frightening reading.

Key findings include a prediction that the number of people with dementia will double by 2030 to over $1 trillion, and more than triple by 2050. Also the costs of caring for people with dementia "are likely to rise even faster than the prevalence – especially in the developing world, as more formal social care systems emerge, and rising incomes lead to higher opportunity costs".

The study also notes that while reports from individual countries such as the UK dementia is one of the costliest illnesses, "research and investment is at a far lower level than for other major illnesses". It makes an eye-catching statement that "if dementia care were a country, it would be the world's 18th largest economy" and if it were a company, "it would be the world's largest by annual revenue exceeding Wal-Mart ($414 billion) and Exxon Mobil ($311 billion).

Daisy Acosta, chairman 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". She added that "world governments are woefully unprepared for the social and economic disruptions this disease will cause".

Commenting on the report, Ruth Sutherland, interim chief executive of the UK's Alzheimer's Society, said that "these shocking statistics provide yet more proof that we cannot afford to ignore the growing global dementia crisis. These sky high figures represent not only a huge economic burden but also reflect the immeasurable impact dementia has on the lives of millions of people across the world".

She concluded by saying that "there are 750,000 people living with dementia in the UK and this number is set to reach a million within a generation. If we are to transform lives and reduce costs we need to act now".