Setting targets for the number of people who should be diagnosed with dementia could lead to "substantial harm" to patients, a GP has said.
An urgent debate is needed before such practices "get out of hand" and lead to patients being diagnosed unnecessarily in a bid to hit targets tied to financial gains, Dr Martin Brunet said.
In November, Health Secretary Jeremy Hunt published a "dementia map" which enables people to look up diagnosis rates in their area. He said the map would drive up standards, showing what dementia care should look like.
But writing in the British Medical Journal (BMJ), Dr Brunet said setting targets and "naming and shaming" areas that do not have high rates was leading to pressure to over-diagnose.
The GP, from Binscombe Medical Centre in Godalming, Surrey, said clinical commissioning groups (CCGs) - groups of GPs looking after the NHS purse strings - were already tying diagnosis rates to income.
He said: " CCGs listed among the 10 worst in the country will be desperate to remove themselves from such scrutiny, and at least one CCG has made the goal into a financial target."
Dr Brunet said Herefordshire CCG has written to local GPs stating: "'The CCG needs to increase prevalence to 40% by April 2014 and 50% by April 2015 - and will lose significant income if we miss these targets'.
"Accompanying the letter was a graph detailing the diagnosis rates of each practice in the CCG, with the implication that those with lower rates needed to work hardest to help the CCG earn this income."
He said GPs would feel under pressure to diagnose dementia when perhaps somebody was suffering cognitive impairment, which may improve on its own.
He said the only factor influencing a diagnosis should be the " best interests of patients".
He added: "The idea that doctors should be motivated by self interest, such as personal or corporate gain, is abhorrent and undermines the basis of the relationship (with a patient).
"The making of a diagnosis is a key moment in a patient's journey. It can bring great benefit by opening the door to effective treatments and support as well as giving a much needed explanation for worrying symptoms. But it can also bring great harm if incorrect."
In a concluding statement, Dr Brunet said that dementia is a "big business" and there are many vested interests that "stand to benefit from a rise in the number of diagnoses".
He said if the validity of these strategies is not questioned, there is the danger of this spreading into other areas of medicine.
A statement from the Alzheimer's Society said: " It is disappointing to hear that there are still some clinicians questioning the benefits of diagnosing dementia. It is not a case of ticking boxes - people with dementia have a right to know.
"Without a diagnosis they are left in the dark without access to treatments, support and information.
"GPs are equipped with the training and tools they need to understand those most at risk of developing dementia. They have the ability to confidently identify and access existing people in their area who are living with dementia and refer them for diagnosis.
"It is wrong to imply that any GP would undermine the trust-based patient-doctor relationship in order to meet targets.
"More than half of people with dementia in England (52%) do not have a diagnosis - only by improving diagnosis rates can we ensure more people are able to live well with the condition and plan for the future."
A Department of Health spokesman said: "A timely diagnosis can make a significant difference to a person's quality of life.
"Sadly less than half of all people with dementia are diagnosed so we are investing £90 million to improve dementia diagnosis and care.
"We would always expect doctors to act in the best interests of their patients, to assess them appropriately when they show the signs of dementia, and refer them to a specialist for diagnosis."