The new millennium has seen the number of people aged 65 years and over grow to be about 423 million, nearly half of whom live in developing countries (World Health Organization, 1993). As Alzheimer's disease increases exponentially with age, dementia will become more common (Reference Evans, Funkenstein and AlbertEvans et al, 1989).

Many studies reveal an increased motor vehicle accident (MVA) rate for drivers with dementia compared with those without dementia (Reference Gilley, Wilson and BennettGilley et al, 1991; Reference Logsdon, Teri and LarsonLogsdon et al, 1992;Reference Friedland, Koss and KumarFriedland et al, 1998). Although 50% of the former stop driving within three years of onset of dementia the risk of an MVA increases with the duration of driving after onset, especially for male drivers (Reference CarrCarr, 1997).

In a Finnish study of men over 70 years old who had stopped driving the most frequently stated reason for stopping driving was deterioration in health (Hakamies-Blomqvist & Wahtstrom, 1998). However, only 6.9% of the ex-drivers had received professional advice to stop driving. In one study, drivers who scored in the lowest 10% on specific cognitive testing were found to be 1.5 times more likely to experience MVAs than those drivers in the highest 10% (Reference Stutts, Stewart and MartellStutts et al, 1998).

The Driving and Vehicle Licensing Agency (DVLA) guidelines for medical practitioners (DVLA, 1998) state:

The DVLA Medical Advice Unit suggests that people with a suspicion of dementia should stop driving until a diagnosis of dementia is excluded.

Aims

The aims of our study were to find out how many patients referred to our Dementia Memory Clinic were still driving at time of assessment despite having cognitive impairment and how many of these were advised to stop by their referrers until assessment had been completed (in accordance with the DVLA Medical Unit's advice).

The study

In a retrospective analysis, the notes of all new referrals to the Dementia Clinic at Pyrland House Old Age Psychiatry Unit, Taunton and a satellite clinic at the district general hospital between June 1998 and May 1999 were scrutinised.

All of those still driving were classified using the ICD-10 (World Health Organization, 1992) and according to results on psychometric testing using Mini-Mental State Examination (Reference Bleecker, Bolla-Wilson and KawasBleecker et al, 1988) and Cambridge Cognitive Examination of the Elderly (CAMCOG) (Reference Hupper, Brayne and GillHupper et al, 1995) assessment scores. Carers were contacted and referral letters scrutinised to see if any advice concerning driving had been given.

Findings

A total of 84 cases were referred to the clinic. Seventeen (20%) patients were still driving at the time of the assessment (5 female, 12 male).

Of the 17, using the above mentioned criteria, the diagnoses were: seven with dementia in Alzheimer's disease with late onset (two female, five male); one with dementia in Alzheimer's disease of a mixed type (male); one patient was found to have no actual cognitive impairment (female); and eight had a mild cognitive disorder (two female, one male).

Of the eight patients in the mild cognitive disorder group CAMCOG scores ranged from 82-101 out of 106 (cut-off for dementia being 80 with up to a 10-point variation for age, socio-economic status and education (Reference Hupper, Brayne and GillHupper et al, 1995)). These variables were not assessed in the study.

Regarding referral letters: one could not be found, two were referrals from general physicians and 14 were from general practitioners.

Although two letters mentioned that the patient was still driving none mentioned that they had advised them to stop driving.

Discussion

This simple study illustrates that when doctors (usually general practitioners) refer a patient with a likely diagnosis of dementia to the Memory Clinic in Taunton they do not document in the letter to the clinic that they have told the patient to refrain from driving until dementia is excluded (admittedly the referring doctor could have documented this in his or her notes and the patient may forget or ignore the advice). In our opinion, if no documentation exists then medico-legal liability may become an issue should an MVA occur.

Our study showed that eight (almost 10%) of the referred patients who were still driving were probably unsafe to do so, as they had a definitive diagnosis of dementia. The group with mild cognitive disorders (almost 10%) showed quite a large variation in CAMCOG scores - these patients we found difficult to decide on how to advise. Storandt & Hill (Reference Storandt and Hill1989) showed that it is difficult to decide who has normal ageing and who has early dementia. Further investigation of the DVLA guidelines and the DVLA medical advice made the following clearer:

1. (a) Where there is a suspicion of dementia the person should be advised to stop driving until assessment by a psychogeriatric team is completed. We suggest that this advice should be documented.

2. (b) All patients diagnosed as having dementia should be told to stop driving and to inform the DVLA. If they disagree that they are unsafe they should ask for a driving assessment from the DVLA, but they should still be advised not to drive until the DVLA has completed its assessment. If the patient passes this assessment then the DVLA may award a time-limited driving licence which may be renewable every six months or so, for example, pending further assessments.

3. (c) All cases that fall into ICD-10 mild cognitive disorder should be assessed to see if they only have age-related memory loss with no other significant areas of cognitive deficit. If this is the case then the psychogeriatric team does not have to advise them to inform the DVLA. However, these patients should undergo a periodic review as their cognitive performance may deteriorate further.

The group with mild cognitive disorder who show cognitive losses in areas other than memory and/or those who have loss of normal daily living skills should be advised in the same way as those with dementia.

The latest General Medical Council guidelines state that it is the doctor's job to inform the patient that the DVLA needs to be informed and that they should refrain from driving pending the DVLA assessment. If they continue to drive then the doctor should tell them that he or she has no choice but to inform the DVLA.