Dementia patients face a gamble with their chances of recovery due to "shockingly poor" treatment offered by some NHS hospitals, the Alzheimer's Society has warned.
A study found "shocking" variations in the standard of care given to dementia patients, with cases of alleged mistreatment including a patient who was restrained with handcuffs and another accused of committing criminal damage by knocking over equipment.
There are thousands of cases of dementia patients being discharged in the middle of the night and, in the worst hospitals, up to 70% of patients who suffered falls on wards had dementia.
Hundreds of millions of pounds has been wasted on poor dementia care in hospitals where at least a quarter of beds are occupied by sufferers who stay for twice as long, new figures reveal.
A survey also revealed extremely low levels of confidence in all hospital staff's understanding of dementia patients' needs.
Alzheimer's Society chief executive Jeremy Hughes warned of the "devastating and life changing" consequences when dementia sufferers received sub-standard care.
He wrote in the report: "Through Freedom of Information requests to hospitals and first-hand testimony collected from people with dementia, their families and carers, we have discovered evidence of the variable care that people with dementia face - in some cases shockingly poor - and the hundreds of millions of pounds of public money wasted delivering it.
"The standards of care differ so much around the country that people are gambling with their health and wellbeing every time they are admitted to hospital."
The true picture of some dementia sufferers' maltreatment had been obscured by "layers of bureaucracy, bad governance and weak regulation," he claimed.
The report calculated £264.2 million was wasted on poor dementia care in 2013/14.
The survey of 570 people, including dementia sufferers and their families, revealed only 2% felt all hospital staff understood the needs of patients with dementia.
Almost 60% of those surveyed felt the dementia patient was not treated with dignity or understanding while in hospital.
Statistics obtained from NHS Trusts under Freedom of Information requests showed 4,926 people with dementia were discharged from hospital between the hours of 11pm and 6am last year.
There were 6,834 incidents of people with dementia falling in hospital during the same period.
In the worst-performing hospitals, 52.2 to 70.6% of people aged over 65 who had a fall in hospital had dementia, according to the charity.
The Alzheimer's Society called for new measures requiring health trusts to publish an annual statement on the quality of dementia care, and for the Care Quality Commission and Monitor to prioritise dementia care in its regulation of hospitals.
A Department of Health spokesman said: "People with dementia and their carers deserve the very best support.
"Improving hospital care for those with dementia is a key component of the Prime Minister's Challenge on Dementia 2020.We have already invested £50 million in creating dementia friendly environments in hospitals and care homes, and more than 500,000 NHS staff have received training on dementia.
"Further tools and training opportunities will be rolled out to all NHS staff by the end of 2018."