Doctors in some areas in England are still "inappropriately over-prescribing" anti-psychotic drugs to dementia patients, campaigners have said.
In the north west 13% of dementia patients are being prescribed the drugs - which are designed to treat conditions such as schizophrenia and can have serious side effects for dementia sufferers - compared to just 2% in London.
Doctors in Yorkshire and the Humber gave 9% of dementia patients the medication while in the north east of England just 2.5% of sufferers were prescribed such drugs, according to data from the Health and Social Care Information Centre (HSCIC).
The Mental Health Foundation said it was "concerned" that the research reveals varying levels of prescriptions around England. Toby Williamson, head of development and later life at the charity said: "This strongly indicates that some areas are still inappropriately over-prescribing."
Unnecessary use of anti-psychotic drugs is killing 1,800 patients prematurely every year, according to the Department of Health.
But overall, the HSCIC figures show that the number of patients being prescribed the drugs has fallen sharply in recent years.
Researchers, who examined data from 197,000 people with dementia, found that in 2011, an average of 6.8% of dementia patients in England were prescribed anti-psychotics compared to 17% in 2006.
HSCIC chief executive Tim Straughan said: "This audit breaks new ground in examining prescribing patterns for dementia patients and highlights areas that GPs and other practices who want to deliver the best possible care need to focus on. It is encouraging that prescribing of anti-psychotic drugs is falling.
"However, it is clear that the picture nationally is mixed and that everyone involved in the care of those with dementia needs to look carefully at how they compare with others in their practices."
Care Services Minister Paul Burstow said: "More than halving the number of people with dementia receiving anti-psychotics marks a huge change in the right direction. It means tens of thousands of people will not be robbed of part of their lives to needless prescribing."