The NHS must urgently address failings in dementia care if it is to cope with future demands, a watchdog has said.
The number of people with dementia is expected to rise
The number of people with dementia is expected to rise by a third in the next 15 years, but the National Audit Office said it was not enough of a priority.
The report said England lagged behind other European countries over early diagnosis and access to drugs.
It likened the situation to cancer in the 1950s when patients were not told about it due to a lack of treatment.
The NAO said only a third of people with dementia are ever formally diagnosed, with many GPs failing to recognise the importance of early diagnosis.
The report said the UK was in the bottom third of European countries for giving drugs to dementia patients, while the average time taken to diagnose patients was twice as long as in some other countries.
It comes as the High Court considers a challenge by drugs companies, backed by the Alzheimer's Society, regarding the decision by the NHS to restrict the use of key Alzheimer's drugs.
The National Institute for Health and Clinical Excellence, which advises the NHS on what treatments to use, has said the drugs Aricept (donepezil), Exelon (rivastigmine) and Reminyl (galantamine) are not cost effective for patients in the early stages of the disease.
It has also said another drug, Ebixa (memantine) - which is licensed for use in the later stages of the disease - should not be recommended for anyone.
Judgment in the case has been reserved, with a ruling expected by early August.
Around 560,000 people in England are estimated to have dementia but, as the population ages, that figure is expected to rise to 750,000 by 2020.
The report put the cost to the NHS and social services of caring for people with dementia at at least £3.3bn a year.
But when other costs, such as carer's time are taken into account, the overall economic burden is estimated to be £14.3bn a year.
'Getting its act together'
The NAO said two thirds of people with dementia live in the community, largely looked after by nearly 500,000 informal carers, who lack support from the NHS.
It also called for more specialist services to be set up.
NAO head Sir John Bourn said: "For too long dementia has not been treated as a high priority.
"Without redesign, services for people with dementia are likely to become increasingly inconsistent and unsustainable."
Neil Hunt, chief executive of the Alzheimer's Society, said: "We must develop health and social care services that can respond to the challenge of dementia."
And Rebecca Wood, chief executive of the Alzheimer's Research Trust, said she hoped the criticisms would lead to the government "getting its act together".
"Too few people are being diagnosed or being diagnosed early enough and things are only going to get worse in the years to come as the population grows older," she said.
Health Minister Ivan Lewis said dementia was "one of the greatest challenges facing our society".
He said funding had been increased and incentives set up to encourage GPs to identify dementia early.
But he added: "We know a lot more needs to be done. We have a duty to strengthen mental health services so they ensure older people and their families are treated at all times with dignity and respect."