The number of prescriptions for drugs to treat Alzheimer's disease is now six times higher than a decade ago.
Data for England shows the number of prescriptions increased from 502,003 in 2004 to three million in 2014.
There has been a Government drive to encourage doctors to diagnose cases of dementia, with GPs receiving payments to boost the numbers.
From October 1, 2014, to March 31, 2015, GPs received £55 for every patient they newly diagnosed with dementia.
This led to a jump in cases - from 336,445 in September 2014 just before the scheme came in to 400,707 at the end of March 2015, according to data from the Health and Social Care Information Centre (HSCIC).
By December 2015, there were 423,000 people diagnosed with dementia.
Overall, the proportion of people who had a diagnosis of dementia in their GP record rose from 643 per 100,000 people in April 2014 to 755 people per 100,000 in December 2015, HSCIC data showed.
The figures on prescriptions, also published by the HSCIC, show that donepezil was the most commonly prescribed drug for Alzheimer's in 2014.
The National Institute for Health and Care Excellence (Nice) recommends the drugs donepezil, galantamine and rivastigmine for managing mild to moderate Alzheimer's disease.
Memantine is recommended for those with moderate Alzheimer's disease who cannot tolerate the other medicines, as well as for managing severe Alzheimer's.
Some £45.7 million was spent on Alzheimer's drugs in 2014, up from £42.8 million in 2004, but down from a high point of £110.8 million in 2011 (when a patent on one drug expired, meaning cheaper generic drugs could be used).
The figures come after research from the Alzheimer's Society found that dementia patients face a gamble due to "shockingly poor" treatment offered by some NHS hospitals.
There were some cases of alleged mistreatment, including a patient who was restrained with handcuffs and another accused of committing criminal damage by knocking over equipment.
The charity said thousands of dementia patients have been discharged in the middle of the night and, in the worst hospitals, up to 70% of patients who suffered falls on wards had dementia.
A new report from the HSCIC also showed that 39% of dementia carers spent 100 or more hours each week in their caring role in 2014/15.
Over half (51%) of carers had been in this role for more than five years.