by Allen J Ruben, MD

At the time of onset of symptons in adulthood, most persons with HD will have subtle, though indistinguishable, changes in function from their normal baselines. Most of these individuals will be licensed drivers and there is no reason to infer, based solely on a diagnosis, that their ability to drive has been compromised. Yey, at the other end of a progressive process of loss of neurological function which may extend over decades, virtually every person with HD will be unable to drive safely. Unfortunately, at some point between these extremes, each person with HD must face this loss of a valued function.

Deciding that the person with HD should not drive is likely to be a difficult decision for the physician, who must balance his obligation to advocate the highest level of independant functioning against his obligation for public safety, and, where there is conflict, must allow public safety to take precedence. At the same time, physicians rarely have specific training in the assessment of driving capacity.

In addition to the more obvious physical prerequisites for driving such as adequate visual acuity and motor strength, there are a number of features of HD to which the physician should pay particular attention, since they are likely to be undermined by the brain dysfunction inherent in HD. These problems will not all occur in any one individual but if significant impairment exists, any one of them could be sufficient to render driving unsafe:

* Alertness and Attention - Drivers must have sustained attention, vigilance, and control of distractibility.

* Aquisition of Visual Information - Drivers must not neglect peripheral visual space or be unable to reposition the eyes quickly; This function can be greatly slowed in HD.

* Processing of Visual Information - Drivers must be able to process information quickly and effectively. Motion and distance must be interpreted correctly.

* Motor Activation - Drivers must be coordinated and effective in the control of movement, be able to sippress intrusive involuntary movements of extremities, and be able to perform several motor functions at once.

* Motor Response - Driving reaction times must be quick and linked to effective problem-solving abilities. The situations encountered in traffic require effective responses to many simultaneous stimuli and changing environments.

* Executive Function - Judgement in driving is vital. A driver must also have the ability to anticipate problems ahead.

* Emotional Status - Drivers must control impulses and temperament, not take undue risks, and not allow driving to express aggression or hope-lessness.

* Denial - A small minority of persons with HD will deny having impairments, even when the impairments are obvious to others. This is a very dangerous trait in a driver.

The physician can take into account the driver’s ability to compensate for an identified difficulty (driving more slowly or restricting oneself to familiar destinations in light daylight traffic, for example). Learning of many recent accidents or near misses is a warning sign, as is a decline in overall functional independence in nondriving situations. When early or minor difficulties are recognised, the physician should re-evaluate every six months.

Driving may continue as long as it is clear that the driver can compensate for early problems, adjust driving circumstances, and exercise adequate judgement to ensure safety. But, where safe driving capacity is less than definite, the person with HD must be instructed to obtain a special assessment, and instructed not to drive until that assessment is obtained and it is determined ( according to his or her province’s criteria ) that driving can resume. Where driving constitutes a danger to personal or public safety, it must stop, and the physician must employ whatever means are at his or her disposal to ensure that it does.

On December 1. 1995, Linda Kyler, a Maryland HDSA member was involved in a car crash. Although her physical injuries were relatively minor, the accident changed her life, and that of her husband forever. Linda, an affected individual driving against medical advice, was at the wheel of a vehicle which killed another driver. Almost immediately, questions were raised: Was Linda at fault? Was her HD to blame? Should her doctors, her family, her friends, or someone else have stopped her from driving? Should Linda have had a license to drive in the first place?.

Due to pending Litigation, the Kylers are unable to talk about the details of this event. That’s unfortunate; although an interview can’t heal their wounds or ease the pain of the slain driver’s family and friends, it might force us all to reconsider the impact of exercising those rights we too often take for granted. The articles in this section will examine some of the issues involved with HD and driving privileges. Along with the Kylers, we’ll try to bring some good out of the tragedy that befell these two families - and hopefully help prevent it from happening again.

Carol Bindel

A license to drive is not a right, it’s a privilege. We as citizens grant each other freedom to drive with the rule of law.

Driving tests establish minimum competency standards. We citizens ask any driver who is at any time experiencing reduced observation, reaction or judgement capacity to refrain from taking the wheel. The freedom in choosing to honour your limits can be a great privilege and wise choices add credit to your character.

Perhaps you are one who is willing to choose lifestyle adjustments before you decline to mere minimum. It can be a gracious act to recognise within yourself that it’s time to stop driving. But no one pretends it is an easy decision.

If you feel you need your license for ID purposes, remember, you can always use other documentation ( IE credit card ). Your identity and your value is entirely separate from your ability to drive a car.

 Hopkins Study:

There has been a lot of discussion recently about whether people with HD can safely drive an automobile. In a recent study of 73 HD outpatients conducted ay John Hopkins, fifty-two (70%) reported that they had continued to drive after being diagnosed. The study was published in 1995 (Rebok, Bylsma, Keyl, Brandt, and Folstein, Automobile Driving in Huntington.s Disease., Movement Disorders. Vol 10. No.6 pp. 778-787).

During the study, 29 HD patients who were still driving were tested on a driving simulator. On this driving task, the patients made errors and reacted more slowly than unaffected drivers. 19 of these patients also completed a driving questionnaire.

The HD patients reported driving roughly the same number of miles per year, under similar weather and traffic conditions, day and night, and on the same mix of roads (neighbourhood streets, secondary roads, freeways ) as unaffected drivers. However, 11 of the patients (58%) reported being in at least one accident in the last two years, a rate more than 5 times higher than that of unaffected drivers (11%). HD patients’ accidents occurred most often in familiar territory: neighbourhoods, local shopping areas, home towns, or secondary roads. The accidents seemed to happen most in the earlier stages of HD, as the patients involved had been sick for shorter periods and were thus able to perform many of their own day-to-day activities.

Patients and their families are encouraged to talk candidly about alternate means of transportation as soon as an HD diagnosis is made ( even better, before the onset of any symptons ) and, for safety’s sake, to have the patient stop driving as soon after diagnosis as possible.

Assistant Professor of Psychiatry and Behavioural Sciences,

John Hopkins University.

 Did You Know?

by Jerome M Levey

Chorea - the random, uncontrolled movement associated with HD - is not always the major cause of driving impairment in affected individuals!

Although it can be a problem for some people, the patient’s judgement is more often the factor which can make HD people dangerous drivers.

Just as teenagers with superb coordination tend to have higher accident rates, HD persons who have little or no chorea may have more accidents due to impaired ability to anticipate situations and make rapid traffic related decisions.

Taken from the March 1998 issue of Gateway the newsletter of the Australian HD Association(NSW) Inc.