Poorer dementia patients in England are less likely to be prescribed the drugs they need, according to new research.
Experts found stark differences in the number of patients given access to the key drugs cholinesterase inhibitors and memantine.
These are the only drugs recommended by the National Institute for Health and Care Excellence (Nice) for Alzheimer's disease.
Nice recommends cholinesterase inhibitors for mild to moderate disease and memantine for severe Alzheimer's and some moderate cases.
Its guidance covers England but is also generally followed in Wales. In Scotland, the NHS allows doctors to follow Nice or less restrictive guidelines from the Scottish Intercollegiate Guidelines Network (Sign), which allow the drugs for any stage of dementia.
In a new analysis of 77,045 patients, experts found that the least deprived patients in England were 27% more likely to be given anti-dementia drugs than the most deprived.
Prescribing rates in England were consistently lower in more deprived patients compared with Scotland, Northern Ireland and Wales, where prescribing was not related to deprivation.
The experts concluded: "Four years after the English National Dementia Strategy, there is no evidence that the strategy's key objective of reducing treatment inequalities is being achieved.
"Higher overall anti-dementia drug prescribing in Scottish and Northern Irish practices, and differing clinical guidelines in Scotland from other UK countries might explain greater equality in prescribing in these countries.
"Strategies to offer treatment to more deprived people with dementia in England are needed."
The new research, published in Age And Ageing, used anonymised medical records from between 2002 and 2013 to identify patients with dementia diagnoses and their prescriptions.
Study author Dr Claudia Cooper, from University College London (UCL), said: "When access to any treatment is rationed, wealthier patients and their families tend to be better-equipped to navigate the healthcare system and get around the restrictions.
"They might do more research and know what to do to get the diagnosis and treatment that they want."
She said inequality in dementia drug prescriptions "looks to be a uniquely English problem" and called for improved strategies.
"These should focus on offering drug treatments to people with treatable dementia types of any severity and ensuring that future prescribing policies do not introduce barriers to care that are less penetrable to people in poorer areas."
George McNamara, head of policy at the Alzheimer's Society, said: "It is unacceptable that such discrimination should exist in accessing healthcare.
"By 2021, there will be over one million people in the UK living with dementia - access to the medication they need should be the same, whether they are living in Kingston-upon-Thames or Kingston-upon-Hull."