Drivers with early dementia are a 'risk to the public'
Derbyshire GP Dr Peter Holden will call for a review of the issue at the British Medical Association's annual conference on Tuesday.
He says vehicles can be a "lethal weapon" in the hands of people who no longer have the ability to drive properly.
He says the current rules and guidance to doctors are out of date.
Everyone has to self-declare whether they are fit to drive at the age of 70 and every three years thereafter.
Although if they have a medical condition, such as epilepsy, they are required to notify the DVLA.
Doctors are asked to help regulate the system by asking patients about their driving abilities if they have concerns.
But Dr Holden said the current system was too one-dimensional, relying on specific diagnoses or on impairment to the senses.
He said there was a risk that people with the early stages of dementia "slip through the net".
Dr Holden added that doctors are increasingly seeing older patients who are driving by rote.
"They stop driving at night, then on motorways, then they go to great lengths not to do right turns," he said.
"But we all know there are times when we need quick reflexes when driving.
"It is a complex task that requires good psycho-motor skills," he added.
However Andrew White, medical adviser to the Driver Vehicle Licensing Agency (DVLA), said it was important to strike "the right balance between safety and personal mobility".
"All drivers must ensure that they are medically fit to drive and notify DVLA of the onset or worsening of a medical condition affecting this," he said.
And George McNamara, of the Alzheimer's Society, said there was a danger of "scaremongering".
"A dementia diagnosis is not in itself a reason to stop driving," he argued.
"The critical issue, both legally and practically, is whether an individual is able to drive safely."
However he conceded that more guidance on this issue was needed.