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The paper reviewed here is ‘Predictors of Driving Safety in Early Alzheimer’s Disease’ by Dawson and colleagues and freely available here. The researchers investigated driving safety in people with early Alzheimer’s Disease compared to a group of older adults without cognitive impairment. Key points in the study include
- 40 drivers with probable early Alzheimer’s Disease
- 115 older adult drivers without neurological disease
- Subjects drove a vehicle 35 miles along an urban route
- Assessment of the video of the driving by a driving expert
- An average of 33.2 v 42 safety errors per drive in the control group versus people with probable early Alzheimer’s Disease (p < 0.00001)
- Lane violations were one of the most common errors
- An additional average of 2.3 safety errors per 5 year increment in age
- A statistically significant inverse correlation between driving safety errors and cognitive performance
The researchers assessed people with probable Alzheimer’s Disease using the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association criteria (NINCDS-ADRDA criteria). The exclusion criteria included a number of neurological and psychiatric illnesses limiting the generalisation of the study findings. The researchers used the MMSE as well as a neuropsychological battery. Ten of the subjects were taking a cognitive enhancer which may have influenced the results (although more evidence is needed from other research).
The people with Alzheimer’s Disease were older. We know from the results of this study that age itself if significantly associated with driving safety errors in this study. However the researchers used their results to test a number of models. These models showed that other factors including a diagnosis of Alzheimer’s Disease and cognitive performance significantly affected the number of driving safety errors independently of age. People with Alzheimer’s Disease showed more lane violations during the driving test. There were two errors in particular that were more common – failing to drive through the traffic lights when they turned green and crossing over the central lines on the road.
When interpreting the results it should be remembered that this is a small study, that the driving safety errors were assessed according to American driving regulations and that people with a range of neurological and psychiatric illnesses were excluded. However the results provide a useful addition to the evidence base.
Appendix – Other Reviews on this Site
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