Abstract
When facing age-related cerebral decline, older adults are unequally affected by cognitive impairment without us knowing why. To explore underlying mechanisms and find possible solutions to maintain life-space mobility, there is a need for a standardized behavioral test that relates to behaviors in natural environments. The aim of the project described in this paper was therefore to provide a free, reliable, transparent, computer-based instrument capable of detecting age-related changes on visual processing and cortical functions for the purposes of research into human behavior in computational transportation science. After obtaining content validity, exploring psychometric properties of the developed tasks, we derived (Study 1) the scoring method for measuring cerebral decline on 106 older drivers aged ≥70 years attending a driving refresher course organized by the Swiss Automobile Association to test the instrument's validity against on-road driving performance (106 older drivers). We then validated the derived method on a new sample of 182 drivers (Study 2). We then measured the instrument's reliability having 17 healthy, young volunteers repeat all tests included in the instrument five times (Study 3) and explored the instrument's psychophysical underlying functions on 47 older drivers (Study 4). Finally, we tested the instrument's responsiveness to alcohol and effects on performance on a driving simulator in a randomized, double-blinded, placebo, crossover, dose-response, validation trial including 20 healthy, young volunteers (Study 5). The developed instrument revealed good psychometric properties related to processing speed. It was reliable (ICC = 0.853) and showed reasonable association to driving performance (R2 = 0.053), and responded to blood alcohol concentrations of 0.5 g/L (p = 0.008). Our results suggest that MedDrive is capable of detecting age-related changes that affect processing speed. These changes nevertheless do not necessarily affect driving behavior.
Highlights
In western Europe we expect the proportion of the population aged 60 years or more to double by 2075 compared to the present, rising from 21 to 42% (Lutz et al, 2008)
Increased life expectancy at birth can be attributed to societal development, reduction of Abbreviations: ANT, attention network test; blood alcohol concentrations (BAC), blood alcohol concentration; CD, coefficient of determination; CFI, comparative fit index; goodnessof-fit statistics (GFI), goodness-of-fit statistics; likelihood ratio tests (LRtest), likelihood ratio test; R2, coefficient of determination; RMSEA, root mean squared error of approximation; SD, standard deviation; SDLP, standard deviation of lateral position to the middle of the road; T1, visual recognition tasks included in MedDrive; T2, central cue attention task included in MedDrive; T3, movement detection task included in MedDrive; T4, spatial working memory task included in MedDrive; TLI, Tucker-Lewis index; UFOV, useful field of view; UFOVmod, modified score combining results from the useful field of view using structural equation modeling; X2, Chi square test
Our only limitation in controlling for effects of alcohol was that participants might not have been completely blinded to their allocation as their guess on which BAC group they were in was above chance (Kappa = 0.383, CI95% 0.255–0.511)
Summary
In western Europe we expect the proportion of the population aged 60 years or more to double by 2075 compared to the present, rising from 21 to 42% (Lutz et al, 2008). Perinatal deaths for both newborns and mothers, a secure environment, and the decreased lethality of diseases. In developed countries, these improvements tend to leave normal aging as the major cause of death. These improvements tend to leave normal aging as the major cause of death This process is the result of chemical changes in cellular metabolism that increase the probability of dying, with age, even under optimal conditions (Harman, 2001). The proportion of the population that will have to change their habits due to these alterations is bound to increase and cause some important societal changes that we need to anticipate (James et al, 2011)
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