There are currently 700,000 people in the UK living with dementia
Care and treatment for sufferers of dementia should be at the heart of the general election campaign, the Alzheimer's Society charity has said.
One in three people over 65 die with dementia and the number of sufferers will rise to a million in 20 years time, according to the charity.
But it says three quarters of 1,500 carers and sufferers they surveyed say the help they receive is inadequate.
The UK spends £27bn a year caring for people with dementia.
This cost is expected to rise along with the ageing population and the number of people who suffer from the condition.
In Scotland, personal and nursing care are free. But three-quarters of carers surveyed elsewhere in Britain told the Alzheimer's Society many of their needs are not being met.
And a quarter thought care staff did not understood the condition.
The society said MPs recognise there is political capital in trying to help, and more than 100 MPs surveyed by the charity said they believed a settlement for the funding of social care needs to be a priority.
Neil Hunt, chief executive of the Alzheimer's Society, said: "It has been reassuring to hear the political parties talking about adult social care this year but now with an election imminent we need more detail.
"We now need to hear guarantees on how each of the parties would provide a fair, transparent and high quality social care system.
"It is unacceptable for a care service to be failing such a vulnerable group to such a staggering degree.
"There are currently 700,000 people in the UK living with dementia. This number will increase to more than a million within 20 years. The vast majority of these people will need some level of social care so it is vital we have a robust system in place that meets their needs."