Sir: Wise and Watson's survey of psychiatrists' knowledge and attitude towards driving and mental illness (Psychiatric Bulletin, September 2001, 25, 345-349) importantly describes the prevalent lack of knowledge and/or willingness to apply the existing Driver and Vehicle Licensing Agency (DVLA) regulations.

They omit to mention patients with dementia who are probably the largest and potentially the most at-risk group of drivers with mental illness.

Driving while suffering from relatively mild dementia (of Alzheimer's or vascular aetiology) can pose a significant risk to other road users and occasionally result in incidents leading to newspaper headlines such as ‘pensioner drives wrong way along motorway’.

The majority of patients with dementia are cared for by their general practitioners and it is primarily their responsibility to be aware of DVLA regulations and to apply them rigorously. This will almost inevitably cause friction in the doctor—patient relationship as many elderly car owners view their right to drive as their only means of continuing to lead an independent life.

Suggestions to patients that they should cease driving are frequently countered by responses such as ‘I only go to the shops twice a week on the same route’ or ‘I've driven for 50 years without problems’.

Allowing a patient to drive while being aware that he/she has a progressive dementing illness could expose the doctor to serious medico-legal consequences.

As the prevalence of dementia rises rapidly in the 8th decade, I suggest there should be more frequent testing of driving ability, possibly including brief tasks of cognitive function for all drivers over the age of 70.