Hospitals are providing "unacceptable" levels of dementia awareness training to their staff, a report published today has found.
The National Audit of Dementia said 95% of hospitals do not have mandatory training in dementia awareness for all staff.
Its report also found that many patients with dementia are not being given mental health tests or nutritional assessments upon admission to hospital.
Geriatric medicine specialist Professor Peter Crome, chair of the report's steering committee, said: "Yet again a report has found marked deficiencies in the case of older people with dementia in general hospitals.
"There is still reluctance by clinicians and managers to accept that the care of this most vulnerable group of patients is a core function of acute hospitals. This must change."
The report, commissioned by the Healthcare Quality Improvement Partnership, looked at the care given to nearly 8,000 patients with dementia at 206 hospitals in England and Wales.
Jeremy Hughes, chief executive of the Alzheimer's Society, said of the findings: "When a quarter of hospital beds are occupied by people with dementia, it is unacceptable that so many hospitals are failing to train their staff.
"Assessing someone's nutritional status is also vital if we are to stop people getting worse in hospital rather than better.
"We know hospital staff want to do a good job but without training and support they are being prevented from providing good-quality dementia care."
The audit found that one third of patients did not have a nutritional assessment recorded, with less than half given a formal mental status test.
One third of patients referred to psychiatry liaison services in the hospitals were not seen for at least 96 hours, it was found.
Professor Crome said: "Assessing and treating dementia patients properly and supporting their carers will not only improve the patients health and quality of life but will also result in shortened hospital stays and reduce both NHS and social care costs."
The report said only 19% of hospitals had a system in place to ensure ward staff were aware a patient had dementia, and how it affected them.
Just 30% of hospitals said they had a formal system for gathering personal information to help them care for people with dementia.
The UK has 750,000 people with dementia, 16,000 of whom are under 65, according to the Alzheimer's Society.
Mr Hughes added: "Despite the obvious lack of improvement in some hospitals, we should not ignore the fact that some are making moves to improve dementia care.
"With the right commitment we can reduce avoidable hospital visits, stop people deteriorating whilst there and allow them to return home rather than moving into care."
Care Services Minister Paul Burstow said: "There can be no excuses for these shocking findings. The audit is a snapshot of the state of dementia care in our hospitals 12 months ago.
"It shines a spotlight on poor practice that demands action from the NHS."
The NHS Operating Framework for 2011-12 released this week emphasised the Government's intention to take action to improve dementia care, he insisted, saying that it was not "rocket science".
Mr Burstow said: "We know what good quality dementia care looks like. None of this is rocket science. There needs to be senior staff leadership on dementia in every hospital to make it a reality.
"By failing to focus on the needs of people with dementia too many hospitals are delivering poor quality and costly care.
"By making sure staff are trained, proper assessments undertaken and timely specialist support on hand, hospitals can deliver the compassionate care people with dementia deserve."