TITLE: Cognitive basis about risk level classifications for the self-assessment of
older drivers

  ABSTRACT:
[Purpose] This study analyzed the cognitive functions according to risk level for the
Driver 65 Plus measure, and examined the cognitive basis of self-assessment for screening
the driving risk of elderly drivers. [Subjects and Methods] A total of 46 older drivers
with a driver's license participated in this study. All participants were evaluated with
Driver 65 Plus. They were classified into three groups of "safe," "caution" and "stop,"
and examined for cognitive functions with Trail Making Test and Montreal Cognitive
Assessment-K. The cognitive test results of the three groups were compared. [Results]
Trail Making Test-A, Trail Making Test-B, and Montreal Cognitive Assessment-K showed a
significant difference between the three groups. The safe group showed significantly
higher ability than the caution and stop groups in the three cognitive tests. In addition,
cognitive functions of naming, attention, language, and delayed recall were significantly
different between the three groups. [Conclusion] Self-assessment of older drivers is a
useful tool for screening the cognitive aspects of driving risk. The cognitive functions,
such as attention and recall, are the critical factors for screening the driving risk of
elderly drivers.

BODY.INTRODUCTION:
Driving ability of older drivers is reduced due to the overall dysfunction involved in the
natural aging process1). Almost half of all
drivers are older, and their accident rate has continued to increase2, 3). Therefore,
recently, elderly driving experts have committed to the screening of at-risk older drivers
to prevent accidents4).  The accident risk of drivers has been reported to be highly relevant to motor ability,
cognitive function, self-regulation ability, and medical condition5, 6). In particular,
cognitive functions have been reported as a key screening element in the elderly driver due
to characteristics of the aging process7).
Therefore, cognitive assessment is used as a driving screening tool for older drivers4). The commonly used cognitive tests include
the Trail Making Test (TMT), Montreal Cognitive Assessment (MOCA), Useful Field of View
(UFOV), Mini Mental State Examination (MMSE), and Clock Drawing Test (CDT)8,9,10).  Older drivers have a self-regulation that can prevent accidents by enhancing the
sensitivity to the changes due to aging11). This ability can be measured through behavior that occurs during the
operation of the self-assessment, and it can be used to monitor the broader population12). The major self-assessments include Driver
65 Plus, the Safe Driving Behavior Measure, SAFER Driving, and the Driving Decisions
Workbook, among others13). In particular,
Driver 65 Plus consists of 15 questions, and it is relatively simple to use; as such, the
facilitation of the monitoring of low concentration elderly drivers is an advantage14).  Despite this advantage, the reliability of the evaluation report by the elderly themselves
is no less a problem14). Therefore,
further evidence that the accuracy of older drivers' self-assessment in driving-related
function is needed to use it for rehabilitation of elderly drivers15,16,17). The research that confirms the ability to the
discrimination of the driving-related functions with self-assessment will provide the basis
for the screening of driving risk in rehabilitation of older drivers. In particular,
verification of cognitive function, a key element in elderly driving, will be an important
basis for elderly driving rehabilitation.  Driver 65 Plus separates the elderly drivers into "Safe", "Caution", "Stop" groups,
depending on their score. Therefore, the analysis on the differences in cognitive function
according to the classification may identify whether there are cognitive effects of
screening the risk of self-assessment.  The purpose of this study was to confirm the basis for screening the driving risk of
self-assessment through analysis of cognitive functions, in accordance with the
classification of Driver 65 Plus.

BODY.SUBJECTS AND METHODS:
Forty-seven older drivers with a driver's license were recruited from August to September
2016. The study participants were enrolled from a senior citizens' center of Korea. All
study protocols were presented to all subjects and written informed consent was obtained
from all participants in accordance with the ethical standards of the Declaration of
Helsinki, 1995. Participants with no senile and neurological disease were included. One
participant with an incomplete assessment was excluded. Forty-six older drivers participated
in this study. Table 1Table 1.General and driving related characteristics of the participants (n=46)CharacteristicsSafe group (n=12)Caution group (n=26)Stop group (n=8)FGender (male/female)11/120/65/31.362Age (years)75.8 ± 5.974.6 ± 4.674.0 ± 5.20.234Education (pre/middle/high/above)3/1/2/64/5/11/62/3/2/11.405Past driving experience (<10/10–20
/>20 years)1/3/83/5/183/1/40.523Driving time per week (<3/3–4/4–5 />5
hours)5/2/1/411/6/6/37/1/0/02.668Accidents resent three months (yes/no)0/122/240/80.819 lists the personal and driving-related characteristics of the participants.
There was no significant difference among the three groups.  This study was carried out by dividing the process into four steps. In the first step,
Driver 65 Plus was used to evaluate the driving risk of the participants. In the second
step, the subjects were classified into three groups according to their score of Driver 65
Plus. In the next step, the safe group (n=12), the caution group (n=26) and the stop group
(n=8) underwent a cognitive function assessment. In the final step, the cognitive test
results of the three groups were compared.  Driver 65 Plus is a self-assessment for screening the risk of the driver, and it was
developed by the AAA (Australian Automobile Association) Foundation for Traffic Safety. It
consists of 15 questions that ask about the behaviors or conditions associated with driving.
The combined scores of each question are defined as "0–15, safe driving," "16–34, caution
driving," and "≥35, stop driving"18).
MOCA-K measures visuospatial executive function, naming, attention, language, abstraction,
delayed recall. It was reported to be associated with driving9). The TMT is divided into the A or B type. TMT-A measures the
response time, attention, sequencing, and visual scanning; and additionally, TMT-B measures
the shift-attention, executive function, and decision-making. They are used to predict
driving risk due to the high association with elderly drivers19).  SPSS 18.0 was used for statistical analysis. An one-way ANOVA was used to assess the
differences in the cognitive functions between the three groups. A p value<0.05 was
considered statistically significant.

BODY.RESULTS:
As listed in Table 2Table 2.Comparison of the cognitive functions between three groupsSafe group (n=12)Caution group (n=26)Stop group (n=8)FTMTTMT-A (second)46.88 ± 13.45a*62.65 ± 30.3983.25 ± 30.00a*4.362*TMT-B (second)103.18 ± 54.15a*,c***165.43 ± 61.23a*,b*232.32 ± 38.53b*, c***12.820***MOCA-KTotal (score)27.12 ± 1.70a*,c***23.42 ± 4.10a*,b*19.50 ± 4.81b*,c***10.060***Visuospatial executive4.00 ± 1.133.92 ± 1.292.75 ± 1.283.040Naming2.92 ± 0.292.81 ± 0.572.25 ± 0.893.591*Attention5.83 ± 0.39a*4.81 ± 1.364.00 ± 1.77a*5.274**Language3.00 ± 0.00a**2.73 ± 0.532.25 ± 0.71a**5.490**Abstraction1.67 ± 0.651.23 ± 0.771.00 ± 0.762.269Delayed recall3.83 ± 1.40a*,b*1.92 ± 1.83a*1.63 ± 1.92b*5.781**Orientation5.92 ± 0.295.77 ± 0.995.63 ± 0.520.329MOCA-K: Korean version of the montreal cognitive assessment; TMT-A: trail making
test-A; TMT-B: trail making test-B. abc Scheffe, *p<0.05, **p<0.01, ***p<0.001, TMT-A, TMT-B, and MOCA-K showed significant differences between the three
groups. The safe group showed higher ability in the three cognitive tests than in the
caution and stop groups. Additionally, the caution group showed higher ability in the TMT-B
and MOCA-K than the stop group. The four items showed a significant difference between the
three groups. The safe group showed higher ability in the items of naming, attention, and
language than the stop group. On the other hand, the safe group showed higher ability in the
item of delayed recall than the caution and stop groups.

BODY.DISCUSSION:
This study classified elderly drivers into "safe," "caution," and "stop" groups through
Driver 65 Plus. TMT and MOCA-K were significantly different between the three groups. Thus,
it confirmed the cognitive basis for the prediction of the risk of elderly drivers with
Driver 65 Plus.  Through Scheffe posteriori test results, TMT-B significant differences were found in all
comparisons between the three groups. In contrast, TMT-A was significant different only
between safe and stop groups. It is interpreted that this was due to TMT-B having more
measures on decision-making, executive function and shift attention, compared to the
TMT-A20). Driving is a highly complex
task that requires attention, memory, response time, decision-making, and executive
function, among other factors21).
Therefore, this can be seen in the results of TMT-B, which measured high-level cognitive
function more sensitively. This result is consistent with the pre-study that indicated that
TMT-B was more effective in predicting the risk of senior drivers19).  MOCA-K (used to measure the overall cognitive functions9)) was significantly different in all of comparisons between three
groups. In addition, it was confirmed that a significant difference between the sub-areas of
naming, attention, language, delayed recall was present. Older drivers are required to have
cognitive functions such as shift-attention, selective-attention, processing speed,
long-term memory, and decision-making22).
Because of this characteristic, it is assumed that there is a difference in the attention
and delayed recall of the study. The difference of the language was determined to be caused
by the evaluation method of Driver 65 Plus. Elderly drivers with a high vocabulary can
respond better to these evaluations that require reading and understanding.  In the other measure, the cognitive functions of orientation and abstraction were also
related with older drivers. But, a significant difference between the groups was not
reported. Nevertheless, the mean of the safe group was higher than the caution and stop
groups. In general, the mean difference analysis is sensitive to the increase of the number
of subjects in the sample23). Because of
the limited sample, it is estimated that the cognitive functions did not show a
statistically significant difference in this study.  Therefore, future research studies that include a sufficient sample size will be needed to
provide strong evidence. This study confirmed the cognitive basis of self-assessment for
elderly drivers. This finding can be used as the evidence for screening dangerous older
drivers through self-assessment in elderly drivers' rehabilitation. Besides this, a
multifaceted study related to older drivers will be required.

Question: Compared to Being in the Stop gruop what was the result of Being in the Caution gruop on MOCA-K ability?
Evidence: The safe group showed higher ability in the three cognitive tests than in the
caution and stop groups. 
Answer: significantly increased