Alzheimer and Vascular Dementias and Driving Fitten L.J.; Perryman K.M.; Wilkinson C.J.; Little R.J.; Burns M.M.; Pachana N.; Mervis R.; Malmgren R.; Siembieda D.W.; Ganzell S. JAMA, May 3, 1995 – Vol 273, No.17

Introduction More than 60% of elderly drivers had some degree of cognitive impairment. Dementia impairs driving and increases accident risk. The study combined on the road and laboratory tests to examine the driving skills of patients with mild AD and VascD.

Methods-Subjects Eight-seven driving subjects were enrolled; 83 completed the study. 17 mild AD patients. 14 VascD patients 15 age-matched patients with diabetes 26 healthy, age-matched, older subjects (60 years above) and 16 young subjects (20 and 35 years).

Low level traffic condition similar to a suburban drive. The road test comprised a six stage driving course 2.7 miles long. Each stage presented a different degree of driving complexity. Methods-Sepulveda Road Test

Laboratory-Cognitive Measures and Mental Status Test. MMSE and the clock-drawing tests of mental status were given the morning of the drive. There were computerized tests of visual tracking, vigilance, divided attention, and STM. Divided Attention- The subject is required to allocate attention to two concurrent tasks(compensatory tracking and a visual search task.)

Sustained Attention- It is used to evaluate the subject’s performance of a prolonged, unvarying task. The task provides no feedback to the subject and uses an infrequent signal in a noisy background. The Sternberg Test-This is a STM test, which may be most relevant to the driving task of remembering road signs long enough to make proper use of them.

RESULTS

Comparison of Distributions Across Study Groups The AD group drove more slowly, had lower mean drive scores, and committed more errors in the complex stages of the course than the three control groups. The AD group had significantly lower performances of visual tracking search and Sternberg than the older control subjects.

Correlation Analysis Drive score correlated most strongly with the Sternberg(0.71), visual tracking(-0.69) and MMSET(-0.63) scores. 利用逐步迴歸得到 (R 2 of 0.68) Drive Score= (MMSET)- 1.23(Visual Tracking)+ 0.34(Sternberg)

Discriminant Analysis

Drive score and number of collisions and moving violations per 1,000 miles driven were negatively correlated (r = -0.38; p <.02).

COMMENT AD 和 VascD 患者在道路測試的績效明顯較對 照組差。 AD 和 VascD 患者會發生嚴重的駕駛錯誤，特 別是在複雜的道路中。 The three factors that best predicted the drive score are the Sternberg test, MMSE and visual tracking.

Based on this study, type and degree of cognitive impairment are better predictors of driving skills than age or medical diagnosis per se. Specific testing protocols for drivers with potential cognitive impairment may detect unsafe drivers effectively as criteria for license restriction or revocation.