Nursing care for people with dementia is in need of a radical overhaul, a leading think tank has warned.
The King's Fund says people with Alzheimer's and dementia in England are having NHS-funded care withdrawn in the later stages of their illness.
It says relatives have to pick up the bill for additional nursing support.
The government says the number of people receiving continuing care has risen by almost two-thirds in the past three years.
There are 820,000 people living with dementia in the UK and that number is set to rise as the population ages, according to the Alzheimer's Research Trust.
Christophe Grillet, from Cambridge, who was diagnosed with Alzheimer's disease 17 years ago, was receiving round-the-clock health care from the NHS at home but as his condition became more advanced, he was reassessed and the continuous care was withdrawn.
His wife Kate said: "They say his needs are primarily social care needs - washing, dressing, feeding and that he's relatively easy to deal with.
"The country is full of people, including my husband, who are having their support taken away and left to try and fund whatever care they can get themselves.
"This doesn't take into account when you have Alzheimer's your health needs are even more, you don't get better."
Mrs Grillet said she felt excluded from much of the decision-making regarding his NHS-funded care and now her husband is in a home which costs them £600 a week.
"Because we didn't get the support we needed, we are separated, and that is the biggest problem," she added.
The government has issued guidelines to primary care trusts (PCTs) on how they should assess the continuing care needs of people with dementia but campaigners say funding cuts mean many PCTs just ignore them.
Barbara Pointon, from Dementia UK and the Alzheimer's Society, said: "What's happening with NHS continuing health care is it's getting more and more difficult to get in the first place, and when people with dementia move into the advanced stage and need more care, it's being taken away from them."
The King's Fund is calling for a shake-up of the system that differentiates between health care, which the NHS pays for, and social care, which local authorities and individuals have to fund.
Richard Humphries, from the health think tank, told the BBC: "The system is increasingly broken and it will struggle to cope with the rising tide of people with dementia and people will become more dissatisfied with it.
"We desperately need a radical overall to bring more fairness and more funding into the system."
Jo Webber, from the NHS Confederation, which represents the majority of NHS organisations, said the service did not have an "infinite pot of money".
"Over the next 30 years the number of people with dementia will double, so we do have to find different ways of delivering services," she said.
"I don't underestimate the anxiety and the worry at the moment for people who are having these issues but we can't go on this way."
A Department of Health spokesman said continuing health care is a package of care - health and personal care and accommodation costs - arranged and funded solely by the NHS for people who have been assessed as having a primary health need. It can be provided in a range of settings, including care homes or a patient's home.
He said since the introduction of the national framework for PCTs, the overall number of people receiving NHS-funded continuing care had risen from just under 31,000 at the end of March 2007 to about 51,000 at the end of September.
"The national framework has started to reduce the regional variation in who gets care and there has been an overall increase in the numbers of people in receipt of NHS continuing health care," he added.
Mr Grillet's PCT says it followed the government's guidelines but health care needs change.