Emergency hospital admissions for people with dementia have increased by 12% in the last five years, according to a new report.
There were 17,245 emergency admissions in 2006/07 but this total had risen by more than 2,000 by 2010/11, costing £2.8 million, according to commissioners.
There were also wide - and unexplained - local variations as one primary care trust (PCT) saw admissions nearly triple, whereas some achieved reductions.
The figures also suggest a continued failure by some hospitals to accurately diagnose people with dementia, researchers said.
Common and Complex: Commissioning Effective Dementia Services In The New World makes 20 recommendations aimed at improving outcomes for people with dementia and reducing costs.
The report, developed following a seminar of dementia experts, identified a series of opportunities but also risks to dementia services created by the health and social care reforms.
In order to improve outcomes and mitigate these risks, the report recommends the Department of Health should work with stakeholders and the Dementia Action Alliance to develop outcome indicators for dementia for inclusion in the 2012/13 NHS Outcomes Framework, and 2012/13 Public Health and Adult Social Care Outcomes Frameworks.
Jeremy Hughes, chief executive of Alzheimer's Society, said: "For many thousands of people with dementia being admitted to hospital is not the best treatment. It is also very costly.
"Commissioners must invest in services in the community to reduce this number and help people with dementia to live well at home. In just 10 years a million people will be living with the condition so change cannot come soon enough."