i Investigating Fitness to Drive in Older Drivers with Cognitive Impairment Anna Devlin B.App.Sci. (Psychology) Honours Submitted in partial fulfillment of the requirement for the degree of Doctor of Psychology (Health) Deakin University March 2013 ii Table of Contents Abstract ....................................................................................................................... ix Acknowledgements .................................................................................................... xii List of Publications .................................................................................................... xiii Conference Presentation ............................................................................................ xiv Terminology and Definitions ..................................................................................... xv Thesis Overview ......................................................................................................... 16 Chapter 1: Introduction .............................................................................................. 18 The Older Driver Problem ...................................................................................... 18 The extent of safety risk for older drivers. .......................................................... 20 The crash patterns of older drivers with cognitive impairment. ......................... 21 The problem for licensing authorities. ................................................................ 22 The problem for health professionals. ................................................................. 25 The importance of maintaining mobility. ........................................................... 27 Addressing the problem of older drivers with cognitive impairment. ................ 29 Chapter 2: Age-Related Cognitive Impairment and Driving ..................................... 31 Cognitive Impairment Defined ............................................................................... 31 Prevalence of mild cognitive impairment. .......................................................... 33 Assessment of cognitive impairment. ................................................................. 34 Telephone interviews for assessing cognitive impairment. ................................ 36 Models of Driver Performance and Cognitive Components .................................. 37 Information processing model of driver behaviour. ............................................ 37 Michon model of driver behaviour. .................................................................... 38 On-Road Driving Performance and Cognitive Impairment .................................... 40 Driver Error and Neuropsychology Test Performance ........................................... 43 Executive function. ............................................................................................. 45 Chapter 3: Older Driver Intersection Approach ......................................................... 47 Braking Behaviour of Older Drivers ...................................................................... 47 Braking Behaviour of Older Drivers with Mild Cognitive Impairment ................. 49 Summary ................................................................................................................. 51 Chapter 4: Rationale and Aims of Study 1 ................................................................. 52 Rationale of Study 1 ............................................................................................... 52 Aims and Objectives of Study 1 ............................................................................. 52 iii Paper 1: Investigating Driving Behaviour of Older Drivers with Mild Cognitive Impairment Using a Portable Driving Simulator .................................................... 53 Preamble to Paper ................................................................................................... 53 Paper 1 .................................................................................................................... 53 Chapter 5: Self-Regulation of Older Drivers ............................................................. 62 Introduction ............................................................................................................. 62 Self-Regulation Defined ......................................................................................... 62 Theoretical Models of Self-Regulation .................................................................. 63 Michon hierarchical model of driver compensatory behaviours ........................ 63 Driving as an Everyday Competence Model. ..................................................... 65 Self-Regulation and Driver Insight ......................................................................... 66 Self-Regulation, Driver Insight and Cognitive Impairment ................................... 68 Summary ................................................................................................................. 69 Chapter 6: Self-Regulation of Older Drivers with Cognitive Impairment: A Systematic Review ..................................................................................................... 71 Preamble to Paper ................................................................................................... 71 Paper 2 .................................................................................................................... 71 Chapter 7: Rationale and Aims of Study Two ........................................................... 79 Rationale of Study Two .......................................................................................... 79 Aims and Hypotheses of Study Two ...................................................................... 79 Paper 3: Self-Regulation of Older Drivers by Cognitive Status: Discrepancy between Driver and Passenger Reports .................................................................. 80 Preamble to Paper ................................................................................................... 80 Paper 3 .................................................................................................................... 80 Chapter 8: Prerequisites for Driving Cessation: Self-Reported and Passenger Reported Factors ....................................................................................................... 110 Introduction ........................................................................................................... 110 Driving Cessation ................................................................................................. 110 Method .................................................................................................................. 111 Approach and Analysis ......................................................................................... 114 Results................................................................................................................... 114 Decline in health or functional abilities. ........................................................... 117 Assessment of road safety risk. ......................................................................... 118 Self-efficacy beliefs. ......................................................................................... 120 External attribution and reliance on others. ...................................................... 120 iv Discrepancy between driver and passenger responses. ..................................... 121 Perspectives of drivers with cognitive impairment compared to those without. ........................................................................................................................... 121 Discussion ............................................................................................................. 122 Summary ............................................................................................................... 125 Chapter 9: General Discussion ................................................................................. 127 Introduction ........................................................................................................... 127 Summary of Key Findings .................................................................................... 128 Key findings from Study 1. ............................................................................... 128 Key findings from Study 2. ............................................................................... 129 Discussion of Findings with Respect to Theoretical Models of Driver Behaviour .............................................................................................................................. 130 Differences between drivers with MCI and age-matched healthy adult drivers. ........................................................................................................................... 130 Self-regulation and self-monitoring. ................................................................. 131 Driving as an Everyday Competence Model. ................................................ 132 Summary: The Impact of MCI on Driver Performance and Driver Competence 133 Limitations and General Comments on the Methodology .................................... 133 Study 1 limitations. ........................................................................................... 134 Study population and sample size. ................................................................ 134 Study design. ................................................................................................. 135 Study strengths. ............................................................................................. 135 Study 2 limitations. ........................................................................................... 136 Driver self-report. .......................................................................................... 136 Obtaining information from collateral sources. ............................................ 137 Sample size and study population. ................................................................ 137 Measure of insight. ........................................................................................ 138 Measure of cognition. .................................................................................... 138 Implications for Research, Policy and Practice .................................................... 139 Implications for licensing authorities. ............................................................... 139 Implications for health professionals. ............................................................... 141 Implications for Australian senior drivers with cognitive impairment. ............ 143 Implications for research. .................................................................................. 144 Directions for Future Research ............................................................................. 145 Conclusions........................................................................................................... 147 v References ................................................................................................................ 148 APPENDIX A: THE PORTABLE SIMULATOR DRIVE EVENTS – STUDY 1 . 179 vi LIST OF FIGURES Figure 1: Information Processing Model of Driver Error……………………….24 Figure 2: Driving as an Everyday Competence Model………………………….52 Figure 3: Key components of the Driving as an Everyday Competence Model...131 vii LIST OF TABLES Table 1: Driver Characteristics……………………………………………………..51 Table 2: Passenger Characteristics…………………………………………………116 Table 3: Key Themes and Subthemes, Definitions and Exemplars Derived from the Telephone Interview Data………………………………………………………….117 ix Abstract The assessment of fitness to drive in older individuals is controversial, with some remaining safe and others presenting at a substantially increased risk. There is a need to explore the nature of any deficits in driving performance in individuals with mild cognitive impairment (MCI), whether they engage in self-regulatory behaviours, and the extent to which they have insight into their driving behaviour. This thesis is comprised of two experimental studies and a systematic literature review. The aim of Study 1 was to establish brake profiles of older adults with and without mild cognitive impairment at intersections using a portable driving simulator. An experimental case-control study was conducted whereby 14 drivers with MCI and 14 age-matched healthy controls completed a simulator drive consisting of stop-sign controlled and signal-controlled intersections. Findings partially supported the hypothesis that compared to healthy older adult drivers, drivers with cognitive impairment would engage in higher risk brake response patterns. Preliminary evidence suggested that drivers with MCI may be less likely to stop at stop-sign controlled, and possibly also at critical light change intersections. The systematic literature review was conducted to identify existing literature on the topic of self- regulation in older drivers with cognitive impairment. Current evidence suggests that many drivers with cognitive impairment do self-regulate by restricting their driving and avoiding certain driving situations. The aim of Study 2 was to investigate the extent to which cognitive status impacts on the decision to self-regulate driving behaviour and to determine whether drivers who self-regulate demonstrate insight into a decline in their driving skills. Older drivers were recruited from the general population in Victoria, Australia. x Findings are presented with respect to cognitive status. Where available, passengers provided an informant view of driver behaviour and an indicator of insight. The findings are discussed in terms of implications for policy and practice regarding older drivers and particularly those with MCI.