The National Institute for Health and Clinical Excellence (Nice) has "opened itself up to ridicule" by publishing contradictory documents, the Alzheimer's Society has said.
In addition to restrictions, coming into force today, to the prescription of Alzheimer's medication for patients in the early stages of the disease, the institute has also published guidelines on how to improve care for people with dementia.
Campaigners have said that these two events release contradictory messages and are an example of confused policymaking.
"By releasing these guidelines today Nice is trying to cynically cloak its flawed evaluation of Alzheimer's drug treatments," said Neil Hunt, chief executive of the Alzheimer's Society.
"On the one hand the health body is moving to improve care and services for people with all types of dementia and with the other snatching away the only drugs that can provide them and their carers with a hugely improved quality of life.
"It's not about care or treatment; people with dementia have the right to both."
However, the society acknowledged that amid the publication were positive recommendations made by the Dementia Clinical Guidelines' expert panel, including calls for improvements to training for care staff and GPs.
The pharmaceutical company which manufactures the drugs in question, Pfizer, has said that it will seek a Judicial Review against Nice's decision to restrict their prescription.