Fitness-to-Drive and Risk acceptance in Huntington's disease

Huntington*s disease (HD) is an autosomal dominant neurodegenerative disorder
which is characterised by a triad of symptoms: motor, cognitive and
behavioural. These symptoms in HD eventually lead to significant decline in
(instrumental) activities of daily living ((i)ADL). The cognitive, motor, and
visual functions that are required for adequate procedural driving skills in a
motor vehicle show a progressive decline in HD as well. Patients with HD are at
a greater risk of overestimating their driving skills and fitness-to-drive
(FTDr) because of impaired self-awareness, which may already be present in
presymptomatic gene carriers. Overestimating FTDr could lead to potential
dangerous situations for HD patients* self and others.

With the proposed study we plan to establish cognitive profiles with classic
neuropsychological tests that correlate with FTDr in HD patients; 1) Fit to
drive, 2) No longer fit to drive, and 3) Dubious fit to drive. For HD patients
who fall into the dubious category, additional testing is required to provide a
more decisive answer regarding their FTDr. In these situations a driving
simulator test, to assess procedural driving skills, in conjunction with the
cognitive profile could clarify the remaining ambiguities. When we are able to
correctly identify patients* FTDr on base of classic neuropsychological tests
and driving simulators assessments, on-road driving tests can be implemented
more specific. This in turn, makes FTDr assessment more cost-effective, safer
and expeditious.

We aim to develop three cognitive profiles to assess FTDr in HD patients; 1)
Fit to drive, 2) No longer fit to drive, and 3) Dubious fit to drive and no
longer fit to drive. The profiles will be determined with classic
neuropsychological tests, complemented with tests that focus specifically on
FTDr, and driving simulator tests.

We propose a cohort study of a population of HD patients.

All participants will attend one test session at the University Medical Center
Groningen (UMCG) for the neuropsychological assessments and the driving
simulator tests. The duration of this session is approximately 4 hours,
excluding intermissions (which are set at the participants* request). The
on-road driving test will be scheduled on a later date at the participant*s
local office of the Dutch driver licensing association; Centraal Bureau
Rijvaardigheidsbewijzen (CBR). The driving test has a maximum duration of 60
minutes. Participants will receive feedback of their performance on the driving
test by the examiner of the CBR.

Benefits of participation in the study are a free extensive assessment of
driving ability. A fail on the driving test has no immediate consequences for
the participant*s drivers* license. Participants who have failed the driving
test are advised to cease driving. However, this advice is not binding.
Participants may experience simulator sickness (similar to car sickness) during
the driving simulator test. Participants are notified of this possibility
beforehand and they will be monitored during the test. They will also be
informed of their right to stop the test at any time.