Dementia and driving: an attempt at consensus.

The number of older drivers in Sweden will be rapidly increasing during the next decades. A possible relationship exists between the increased relative crash risk of older drivers and the prevalence of age-related diseases such as dementia. However, a clear-cut policy for evaluating driving competence in demented persons is still lacking. In recognition of this fact, the Swedish National Road Administration invited a group of researchers to formulate a consensus on the issue of driving and dementia. This consensus document is aimed at providing primary care physicians with practical advice concerning the assessment of cognitive status in relation to driving. Suggestions are based on a review of existing research and discuss the use of general and driving-specific sources of information available to the physician. Consensus was reached on the statement that a diagnosis of moderate to severe dementia precludes driving and that certain individuals with mild dementia should be considered for a specialized assessment of their driving competence.

Can a physician recognize an older driver with increased crash risk potential?

OBJECTIVE: To identify factors in a medical examination that distinguish convicted older drivers with traffic violations from other drivers. DESIGN: Matched case-control study. SETTING: Two countries in Sweden. SUBJECTS: Thirty-seven drivers older than age 65, whose driving licenses have been temporarily suspended, each matched to one control subject based on age, sex, type of driving license, year of first license, living area, educational level, and annual distance driven. MEASUREMENTS: Case and control subjects were compared with respect to medical history, medication use, blood tests, drawing and memory tests, Mini-Mental State Examination, medical status findings, visual acuity, and brain imaging procedures. MAIN RESULTS: The group of drivers with suspended driving licenses did not differ from matched controls with respect to visual acuity or presence of cardiovascular diseases. However, persons with suspended driving licenses were more likely than control subjects to have suspected or mild dementia (P < .010) and to perform less well on two easily administrated screening tests: copying a cube (P < .010) and 5-item recall (P < .010). Case subjects with crashes had significantly more cardiovascular diseases than case subjects with other moving violations (P < .050). These case subjects with crashes also had significantly more cognitive impairments than control subjects without crashes as shown by a higher clinical dementia rating score (CDR) (P < .001), lower score on the Mini-Mental State Examination (MMSE) (P < .050), and lower level of performance in the copying task (cube) (P < .050) and 5-item recall test (P < .010). They also had evidence of greater cognitive impairment than those case subjects with other moving violations. CONCLUSIONS: Visual acuity and common medical examination did not distinguish convicted older drivers with crashes or other moving violations from controls. There was evidence that even mild cognitive impairment contributed to the risk of losing a driving license because of crashes.

Dynamics of accommodative vergence movements controlled by the dominant and non-dominant eye.

Accommodative vergence responses to accommodative stimuli presented at three different amplitudes in a stepwise and a sinusoidal mode to either the dominant or the non-dominant eye were studied. The motor control loop was opened by one eye viewing the target and the other eye covered. Each eye was stimulated monocularly and eye movements were recorded with an infra-red reflection system. Latency and time constant of the accommodative vergence response to step stimulation or the phase of the vergence response to sine wave stimulation, did not vary systematically with stimulus amplitude or eye stimulated. However, the gain of the accommodative vergence movements was highest in the non-dominant eye at a particular stimulus amplitude. This suggested that accommodative vergence angles can vary depending on which eye is leading and driving the accommodative vergence system in a specific fixation situation.