MS 'can increase road accident risk'

Driving reaction times can be slowed by MS

Some people with multiple sclerosis have slower driving reaction times and an increased risk of accidents, say scientists.

While MS is predominately a physical condition, some patients also have difficulties with mental, or cognitive, abilities such as perception, intuition and reasoning.

The research was based on two computerised driving tests given to people with MS.

Scientists examined 13 MS patients who had problems with perception, intuition and reasoning, and 15 people with MS who did not show the difficulties, based on several neuropsychological tests.

Comparisons were also made with 17 people who did not have MS.

This is the first study to provide direct evidence that cognitive difficulties among people with MS can influence driving

Dr Maria Schultheis

Based on the tests, those with MS who exhibited cognitive difficulties had a slower response time by 1,721 milliseconds than the other MS participants.

In addition, 29% of these people tested as high risk for accident involvement.

Researcher Dr Maria Schultheis, of Kessler Medical Rehabilitation Research and Education Corporation in New Jersey, US. said: "This is the first study to provide direct evidence that cognitive difficulties among people with MS can influence driving.

'Alarmism' danger

"Previous studies have only looked at physical problems resulting from MS in relation to driving capabilities, not cognitive difficulties."

But David Harrison, a spokesman for the UK's MS Society, told BBC News Online it was important not to extrapolate too much from the results of a small study, or promote alarmism about the driving skills of people with the condition.

"This study talks about people who exhibited cognitive difficulties and the general feeling is these people were aware that they did have difficulties.

"MS is a hugely variable condition - the way it impacts upon the lives and capabilities of people is very varied.

"If people are experiencing cognitive difficulties and have concerns about what impact that might have on their driving skills they should certainly discuss that with their neurologists.

Accident risk

"There are assessment centres which people can go to test their driving skills."

The single session of driving tests examined attention span and the driver's ability to process rapidly presented information, to calculate the driver's risk of accident.

MS is a hugely variable condition - the way it impacts upon the lives and capabilities of people is very varied

David Harrison
MS Society

Another test examined driving ability through self-evaluation questions, simulated driving tests and scenarios, and visual field assessments.

Ms Schultheis said the prevalence of cognitive difficulties in MS has only been recently recognised.

Comprehensive evaluation

Estimates of those with cognitive difficulties range from about 43-65%, although the severity and impact of these on everyday life varies and scientists acknowledge more research is required.

"Hopefully, this study will alert clinicians to consider cognitive factors in relation to MS when they are evaluating an individual's driving capabilities, and provide a more comprehensive evaluation for people," said Ms Schultheis.

Although a difference in reaction time was found between the two groups of MS participants, there was little difference in reaction time between people without MS and people with MS who did not experience cognitive difficulties.

Ms Schultheis hoped future studies could include more "real life" driving scenarios.

The research is published in Neurology, the journal of the American Academy of Neurology.