Effects of Different Types of Cognitive Training on Cognitive Function, Brain Structure, and Driving Safety in Senior Daily Drivers: A Pilot Study

Abstract

Background: Increasing proportion of the elderly in the driving population raises the importance of assuring their safety. We explored the effects of three different types of cognitive training on the cognitive function, brain structure, and driving safety of the elderly.

Methods: Thirty-seven healthy elderly daily drivers were randomly assigned to one of three training groups: Group V trained in a vehicle with a newly developed onboard cognitive training program, Group P trained with a similar program but on a personal computer, and Group C trained to solve a crossword puzzle. Before and after the 8-week training period, they underwent neuropsychological tests, structural brain magnetic resonance imaging, and driving safety tests.

Results: For cognitive function, only Group V showed significant improvements in processing speed and working memory. For driving safety, Group V showed significant improvements both in the driving aptitude test and in the on-road evaluations. Group P showed no significant improvements in either test, and Group C showed significant improvements in the driving aptitude but not in the on-road evaluations.

Conclusion: The results support the effectiveness of the onboard training program in enhancing the elderly's abilities to drive safely and the potential advantages of a multimodal training approach.

Figure 1

Flow diagram of this study.

Figure 2

Changes in the cognitive function composite scores in each training group. (a) Processing speed was evaluated as a composite of the Trail Making Test- (TMT-) A and Symbol-Digit Modalities Test (SDMT) measures. (b) Executive function was evaluated as a composite of the Frontal Assessment Battery (FAB), Word Fluency Test (WFT), and TMT-B test measures. (c) Working memory was evaluated as a composite of the Spatial Span (SS), Benton Visual Retention Test (BVRT), and Auditory-Verbal Learning Test (AVLT) measures. (d) Composite measure of cognitive impairment (COGSTAT) [5] was evaluated by combining the Block Design (BD), WFT, TMT-B, BVRT, Complex Figure Test- (CFT-) Copy, CFT-Recall, AVLT, and Judgment of Line Orientation (JLO) scores. Score changes were adjusted for age, sex, and Pre (baseline) scores. The error bars in the graphs show the standard errors of the mean (SEM) for the subjects in each group.

Figure 3

Group V showed significant rGMV increases in the left inferior frontal gyrus (a). Group P showed significant rGMV increases in the right middle frontal gyrus and the left superior occipital gyrus (b). Group C showed significant rGMV increases in the left dorsolateral prefrontal cortex (c) and significant rGMV decreases in the precuneus, the medial cerebellum, and the right caudate (d). The colored clusters show regions with rGMV changes that were significant with a family-wise error corrected P < 0.05 at the nonisotropic adjusted cluster level [59], with an underlying voxel level of P < 0.001.

Figure 4

Significant between-group difference in regional gray matter volume (rGMV) changes. (a) In the structures around the right caudate, the rGMV changes were significantly different between Groups P and C. The colored cluster shows the region that exhibited significant differences in rGMV change with family-wise error corrected P < 0.05 at the nonisotropic adjusted cluster level [59] with an underlying voxel level of P < 0.001. (b) The average of rGMV changes in each group shows that the differences in the region were largely because of the rGMV increases in Group P. The error bars in the graph show the 95% confidence intervals.

Figure 5

Tract-based spatial statistical analysis in Group C detected significant increases (Post and Pre) in fractional anisotropy (FA) in the left posterior white matter. Gray: MNI152 T1 template image, green: intergroup average white matter skeleton, and red-yellow: voxels that show threshold-free cluster enhancement-corrected significant (P < 0.05) increases in FA in Group C. Note that the images are displayed according to radiological convention, with the right hemisphere on the left.

Figure 6

Changes in driving safety measures in each training group. The measures are as follows: (a) the total grades obtained from the driving aptitude test unit and (b) the total grades obtained from the on-road driving safety test. The score changes were adjusted for age, sex, and Pre (baseline) scores. The error bars in the graphs show the standard errors of the mean (SEM) of the subjects in each group.