What is the NHS there for?
The argument that dementia patients are getting a poor deal goes to the heart of the debate about what the NHS is there for.
When the NHS was created in 1948, the focus was on protecting people from infectious diseases. Now - with people living longer - it is increasingly about helping patients manage illness.
There are an estimated 15m people in England in this situation. They have been diagnosed with long-term, incurable conditions, such as dementia.
But there is a limit to how far health service resources will stretch to support them - already an estimated 70% of the budget is spent on caring for these patients.
The result is that many patients are finding their needs classed as social care, which is the responsibility of councils. But that is a means-tested system - which results in only the least well-off getting help - and, increasingly, being rationed to those with the most severe needs anyway.
Just over 1m people are currently getting help from councils. Those who do not qualify face one of three choices: go without care, pay for it or rely on family and friends to step in.
For dementia, according to the research published by the Alzheimer's Society on Wednesday, two thirds of care falls into this category.
The charity says the lack of support amounts to a "care tax". It compares the support dementia patients get with the help on hand for cancer patients.
This is understandable. There are a whole range of treatments for cancer from surgery and radiotherapy to a host of drugs.
For dementia, there is very little. There are a few drugs that can slow progress of the disease, but these don't work for everybody.
Instead, these patients rely on care and support to manage their condition and daily lives as best they can.
Some of this takes the form of official services, such as singing groups, memory clinics and dementia cafes (although the NHS relies heavily on the voluntary sector to provide these).
Much of the rest - which covers everything from help with daily tasks such as washing, dressing and eating to care homes places - falls outside the remit of the NHS.
Long-term health issues
people in England have a long-term health condition
By 2025, that could be18m
70% of the NHS Budget is spent on caring for them
But, of course, dementia patients are not the only ones who find themselves on this side of the fence. Even cancer patients can.
Half can now expect to survive for 10 years or more, but survival comes at a cost. Research by Macmillan Cancer Support has shown that one in four survivors live with a debilitating condition.
That is partly why, according to the charity, a cancer diagnosis leaves patients out of pocket by hundreds of pounds a month along with the extra hospital travel costs and loss of income they endure.
Ministers are responding. The government in England is in the process of encouraging more joint working between the NHS and social care systems, while Labour has said it is looking to develop its own plans.
Others believe a more radical solution is needed. Last week the Barker Commission - set up by the King's Fund - called for the two systems to be merged and social care to be offered on the same basis as the NHS - free at the point of need.
But that costs money - about £5bn a year the commission estimated - and there is not a lot of that about. Meeting this challenge is posing all sorts of difficult questions.