Traffic Psychology Factsheets
Dementia & Alzheimer
car driving
• Driving scores decrease with increasing dementia.
• Patients with AD made most errors on the tactical level (lane positioning, lane changing,
checking the blind spot, slower driving and stopping appropriately)
• On the operational level, errors in turning signalling and lane maintenance occur.
• Strategic errors included less attention while driving, slower decision making and difficulties
with road rules.
• Compared to patients with Parkinson’s disease, AD patients made more mistakes on the
operational and strategic levels.
• Patients who failed an on road assessment scored worse on neuropsychological tasks (speed
of processing, executive functioning, attention, memory, visuospatial abilities)
• Patients are not able to judge their own driving behaviour. The rating by a neurologist was
more optimistic compared to the rating performed by a driving instructor and psychologist.
Spouses tend to overestimate driving ability of AD patients. Ratings by adult children were
more accurate.
• In most studies, more than half of the patients with a neurodegenerative disorder were
classified as safe drivers.
• Individual evaluations are important and changes in driving performance should be
monitored regularly, preferably every year.
Parkinson
car driving
• PD patients are most likely to make errors on the tactical level including difficulties with
yielding at intersections, lane changing, mirror use, adjusting to traffic situations and other
road users, road positioning and they hesitated more, had an unsteady car speed and drove
slower.
• On the operational level, PD patients made more incorrect turns, did not signal appropriately
and made errors in lane maintenance.
• On the strategic level, PD patients made fewer driving trips, drove less distance and shorter
durations.
• Most studies reported associations between cognitive functioning and driving competence,
but results are inconsistent. Driving errors were mostly associated with lower performance in
cognitive flexibility, visuoconstructional abilities, attention, psychomotor speed working
memory, set shifting, information processing, and visual functions (scanning, memory,
acuity).
Bicycle patient with Freezing of Gait
• Case report of a 58-year-old man with longstanding PD who was grounded by severe Freezing
Of Gait (FOG). To our surprise, this patient manifested a strikingly preserved ability to ride his
bicycle.
, • Cycling could provide external pacing cues that are less prominent during gait. It is well
known that external sensory cues are effective in overcoming the defective basal ganglia
circuitry of PD patients, perhaps by activating the motor cortex via alternative circuits.
• The pedals could restore two mechanisms that have been implied in the pathophysiology of
FOG: the inability of PD patients to generate and maintain appropriate movement amplitudes
and the abnormal temporal coordination between both legs. In contrast to gait, cycling
provides the patient with a mechanical constraint that keeps step length constant. In
addition, it corrects the coupling between central commands and the biomechanical
constraints of the legs.
• Both acts evoke similar modulations of cutaneous reflexes but compared to walking, cycling
may require much less unloading to the weigh-bearing leg.
• PD patients with FOG have specific difficulties in generating these preparatory lateral weight
shift.
• Dynamic balance control is also different during cycling and walking. Various studies have
shown that balance deficits in PD are directionally dependent, being greatest in the backward
direction, and much less so in the mediolateral direction. This relatively preserved
mediolateral stability could also explain why PD patients typically walk with a narrow-based
gait and why tandem gait is preserved in most patients.
• FOG commonly leads to a decreased mobility and loss of independence.
• Our patients felt secure while cycling, but reported difficulties and occasionally falls during
mounting or dismounting the bicycle, particularly when it was unexpected. Cycling on a
normal bicycle is therefore not ideal for all patients, but a tricycle can be a good alternative.
Additional concerns relate to busy traffic and the need for duals tasking, which is problematic
in PD.
Car driving
• Prior studies showed that impairments in driving in PD patients are associated with deficits in
contrast sensitivity, visual processing, set-shifting and psychomotor speed.
• A retrospective survey found that patients with H&Y stages 2 and 3 had a significantly higher
crash risk compared to healthy controls. However, there was no evidence of increased crash
risk among patients in H&Y stage 1.
• Recently, a prospective cohort study compared drivers with PD to drivers without neurologic
conditions and found no clear link between PD and occurrence of real-life crashes.
• Clinicians/ neurologists often overestimate the driving ability of their patients with PD
• Most drivers with PD had significantly worse driving performance than healthy controls.
Although most drivers with PD were considered safe to drive, deficits that may affect driving
were apparent even in the early stages of PD.
• H&Y stage are probably not predictive of driving performance. Disease duration is also not
predictive of driving performance.
• Contrast sensitivity was probably predictive of driving performance, the UFOV was probably
predictive of impaired driving performance.
• The Rey complex figure, the trail making test B and the TMT B-A are probably predictive of
driving performance.
• UPDRS motor scores, H&Y stages, disease duration, GDS and MMSE scores are probably not
predictive of driving performance.
, • Besides the UFOV risk index score, which needs to be replicated in larger studies, we cannot
suggest any cut-offs for the remaining risk factors that would indicate a high-risk driver or a
patient with PD who should discontinue driving.
• Disease severity indices captures mainly motor symptoms and do not capture visual or
cognitive deficits. As visual attention, spatial and executive skills are critical abilities for
driving in general, it is not surprising that these indices are not predictive of driving
performance.
Car driving
o Increased daytime sleepiness may impact driving in PD
o It is estimated that PD patients often continue driving during the first decade of their illness.
o PD drivers were more reliant on external cues (road signs) to regulate driving)
o This result suggests that external cues, such as driving assistance systems might be useful for PD
drivers.
o The impairment of key executive skills compromises tactical level driving behaviours in patients
with PD. Moreover, an impairment of lower order cognitive skills such as information processing
speed, attention to detail and basic visuoperception involves difficulties in driving behaviours at
the operational level.
o PD patients performed significantly less well the concurrent task than controls as suggested by
the authors, it is likely that PD drivers sacrificed concurrent task performance to maintain driving
ability.
o However, PD drivers were able to maintain appropriate driving behaviour especially in low or
moderate attentional demanding conditions which is an important result for road safety.
o The main finding was an impairment of updating function in early stages if PD whereas there
were not differences in flexibility tasks between the two groups. It also appeared that updating
task on driving simulator have a greater impact on driving performances for both groups,
suggesting that updating task is more demanding than flexibility task.
o Decline in visual attention, visual construction, visual memory and general cognition appeared to
be significant predictors of total error counts within the PD group.
o The SDMT correlated significantly with the average driving safety score.
o It has been suggested that neuropsychological measures requiring rapid responding, visual spatial
cognition and executive functioning are most useful for distinguishing safe from marginal drivers.
o Two on-road studies confirm the usefulness of TMT for clinician to predict driving performances
in PD drivers. Clinical indices such as disease duration, motor score or H&Y scale have not been
shown as reliable predictors of driving performances in most studies suggesting that they cannot
be used alone as relevant indicators of safe driving.
o The TMT, SDMT, UFOV and block design tests are good predictors of driving or have strong
correlations with driving performances in patients with PD.
o While there is no consensus about real crash risk in PD, there is clear evidence that AD patients
have an increased risk of crashes compared to age-mitched controls.
o Tests used to predict driving in AD patients are similar to those used in PD patients. However, AD
patients exhibit severe deficits in all tests whereas PD patients with mild-to-moderate stages have
more specific and discrete alternations especially in executive and visuospatial functions.
o Accordingly, as in PD, TMT-B, SDMT or Block design are reported as good predictors of unsafe
driving in traumatic brain injured patients.
(Uc, et al., 2011)
• The incidence of driving cessation in drivers with PD was higher than in neurologically healthy
control drivers.
Dementia & Alzheimer
car driving
• Driving scores decrease with increasing dementia.
• Patients with AD made most errors on the tactical level (lane positioning, lane changing,
checking the blind spot, slower driving and stopping appropriately)
• On the operational level, errors in turning signalling and lane maintenance occur.
• Strategic errors included less attention while driving, slower decision making and difficulties
with road rules.
• Compared to patients with Parkinson’s disease, AD patients made more mistakes on the
operational and strategic levels.
• Patients who failed an on road assessment scored worse on neuropsychological tasks (speed
of processing, executive functioning, attention, memory, visuospatial abilities)
• Patients are not able to judge their own driving behaviour. The rating by a neurologist was
more optimistic compared to the rating performed by a driving instructor and psychologist.
Spouses tend to overestimate driving ability of AD patients. Ratings by adult children were
more accurate.
• In most studies, more than half of the patients with a neurodegenerative disorder were
classified as safe drivers.
• Individual evaluations are important and changes in driving performance should be
monitored regularly, preferably every year.
Parkinson
car driving
• PD patients are most likely to make errors on the tactical level including difficulties with
yielding at intersections, lane changing, mirror use, adjusting to traffic situations and other
road users, road positioning and they hesitated more, had an unsteady car speed and drove
slower.
• On the operational level, PD patients made more incorrect turns, did not signal appropriately
and made errors in lane maintenance.
• On the strategic level, PD patients made fewer driving trips, drove less distance and shorter
durations.
• Most studies reported associations between cognitive functioning and driving competence,
but results are inconsistent. Driving errors were mostly associated with lower performance in
cognitive flexibility, visuoconstructional abilities, attention, psychomotor speed working
memory, set shifting, information processing, and visual functions (scanning, memory,
acuity).
Bicycle patient with Freezing of Gait
• Case report of a 58-year-old man with longstanding PD who was grounded by severe Freezing
Of Gait (FOG). To our surprise, this patient manifested a strikingly preserved ability to ride his
bicycle.
, • Cycling could provide external pacing cues that are less prominent during gait. It is well
known that external sensory cues are effective in overcoming the defective basal ganglia
circuitry of PD patients, perhaps by activating the motor cortex via alternative circuits.
• The pedals could restore two mechanisms that have been implied in the pathophysiology of
FOG: the inability of PD patients to generate and maintain appropriate movement amplitudes
and the abnormal temporal coordination between both legs. In contrast to gait, cycling
provides the patient with a mechanical constraint that keeps step length constant. In
addition, it corrects the coupling between central commands and the biomechanical
constraints of the legs.
• Both acts evoke similar modulations of cutaneous reflexes but compared to walking, cycling
may require much less unloading to the weigh-bearing leg.
• PD patients with FOG have specific difficulties in generating these preparatory lateral weight
shift.
• Dynamic balance control is also different during cycling and walking. Various studies have
shown that balance deficits in PD are directionally dependent, being greatest in the backward
direction, and much less so in the mediolateral direction. This relatively preserved
mediolateral stability could also explain why PD patients typically walk with a narrow-based
gait and why tandem gait is preserved in most patients.
• FOG commonly leads to a decreased mobility and loss of independence.
• Our patients felt secure while cycling, but reported difficulties and occasionally falls during
mounting or dismounting the bicycle, particularly when it was unexpected. Cycling on a
normal bicycle is therefore not ideal for all patients, but a tricycle can be a good alternative.
Additional concerns relate to busy traffic and the need for duals tasking, which is problematic
in PD.
Car driving
• Prior studies showed that impairments in driving in PD patients are associated with deficits in
contrast sensitivity, visual processing, set-shifting and psychomotor speed.
• A retrospective survey found that patients with H&Y stages 2 and 3 had a significantly higher
crash risk compared to healthy controls. However, there was no evidence of increased crash
risk among patients in H&Y stage 1.
• Recently, a prospective cohort study compared drivers with PD to drivers without neurologic
conditions and found no clear link between PD and occurrence of real-life crashes.
• Clinicians/ neurologists often overestimate the driving ability of their patients with PD
• Most drivers with PD had significantly worse driving performance than healthy controls.
Although most drivers with PD were considered safe to drive, deficits that may affect driving
were apparent even in the early stages of PD.
• H&Y stage are probably not predictive of driving performance. Disease duration is also not
predictive of driving performance.
• Contrast sensitivity was probably predictive of driving performance, the UFOV was probably
predictive of impaired driving performance.
• The Rey complex figure, the trail making test B and the TMT B-A are probably predictive of
driving performance.
• UPDRS motor scores, H&Y stages, disease duration, GDS and MMSE scores are probably not
predictive of driving performance.
, • Besides the UFOV risk index score, which needs to be replicated in larger studies, we cannot
suggest any cut-offs for the remaining risk factors that would indicate a high-risk driver or a
patient with PD who should discontinue driving.
• Disease severity indices captures mainly motor symptoms and do not capture visual or
cognitive deficits. As visual attention, spatial and executive skills are critical abilities for
driving in general, it is not surprising that these indices are not predictive of driving
performance.
Car driving
o Increased daytime sleepiness may impact driving in PD
o It is estimated that PD patients often continue driving during the first decade of their illness.
o PD drivers were more reliant on external cues (road signs) to regulate driving)
o This result suggests that external cues, such as driving assistance systems might be useful for PD
drivers.
o The impairment of key executive skills compromises tactical level driving behaviours in patients
with PD. Moreover, an impairment of lower order cognitive skills such as information processing
speed, attention to detail and basic visuoperception involves difficulties in driving behaviours at
the operational level.
o PD patients performed significantly less well the concurrent task than controls as suggested by
the authors, it is likely that PD drivers sacrificed concurrent task performance to maintain driving
ability.
o However, PD drivers were able to maintain appropriate driving behaviour especially in low or
moderate attentional demanding conditions which is an important result for road safety.
o The main finding was an impairment of updating function in early stages if PD whereas there
were not differences in flexibility tasks between the two groups. It also appeared that updating
task on driving simulator have a greater impact on driving performances for both groups,
suggesting that updating task is more demanding than flexibility task.
o Decline in visual attention, visual construction, visual memory and general cognition appeared to
be significant predictors of total error counts within the PD group.
o The SDMT correlated significantly with the average driving safety score.
o It has been suggested that neuropsychological measures requiring rapid responding, visual spatial
cognition and executive functioning are most useful for distinguishing safe from marginal drivers.
o Two on-road studies confirm the usefulness of TMT for clinician to predict driving performances
in PD drivers. Clinical indices such as disease duration, motor score or H&Y scale have not been
shown as reliable predictors of driving performances in most studies suggesting that they cannot
be used alone as relevant indicators of safe driving.
o The TMT, SDMT, UFOV and block design tests are good predictors of driving or have strong
correlations with driving performances in patients with PD.
o While there is no consensus about real crash risk in PD, there is clear evidence that AD patients
have an increased risk of crashes compared to age-mitched controls.
o Tests used to predict driving in AD patients are similar to those used in PD patients. However, AD
patients exhibit severe deficits in all tests whereas PD patients with mild-to-moderate stages have
more specific and discrete alternations especially in executive and visuospatial functions.
o Accordingly, as in PD, TMT-B, SDMT or Block design are reported as good predictors of unsafe
driving in traumatic brain injured patients.
(Uc, et al., 2011)
• The incidence of driving cessation in drivers with PD was higher than in neurologically healthy
control drivers.
