Driving. Can older people keep driving?

• Q. Can we maintain our driving capacity?

• A. Try training your speed of processing, expand your visual field and put in some practice!

I don’t think anyone really wants to give up their driving license. It has been held for a long time. My friend who is 84 and now on dialysis said “They took my license from me!”  It is hard to accept these up-front changes as you get older. And who makes the final decision? It’s not easy to tap your father on the shoulder and say “Dad, you shouldn’t be driving.” Driving for many people is about independence, about mobility, about maintaining an active lifestyle, being part of a social group, it’s just what you do. Even if it’s convenient to walk to your local store or by the river or into the bush it is still useful to hold a driving license, just in case.

In Australia, as in many other countries, we have an increasing elderly population. Currently 15.9% of Australians are over the age of 65 years and this number is predicted to increase to 22.8%  by 2031. The improved lifestyle expectations of those in this age group (with the “baby-boomers” looming behind them!) will result in an increase in the number of older people who drive and expect to continue driving.

What makes people give up driving?

Many older drivers’ self-impose restrictions on their driving. It is known that with increasing age there is a decline in sensory, cognitive and motor function and older drivers do have more accidents per kilometer than younger drivers.

A research study in Maryland, USA followed 1,248 older people over a 10 year period. (That’s a good long follow-up to see what happens over time! )

The drivers were assessed at the start of the study for both physical and cognitive ability, and then again at 5 years and 10 years. The researchers wanted to know what predicted those individuals who gave up driving.

• Age is obviously involved, (that’s something we can’t avoid). The older people were when they started the study the more likely they were to stop driving during the 10 year period.

• Number of days driven per week: so if you don’t keep practicing your driving skills you are more likely to give up.
  

• Speed of processing as measured by the Useful Field of View Test (UFOV)

Driving requires the ability to detect and process visual information from both the peripheral and central visual fields at the same time. The useful field of view (UFOV) test was developed by Ball and co-workers(1993) .

Increase in UFOV from training

It attempts to measure the span of attention within the visual field.  As I practiced the Posit Science Insight program exercises I became fully aware of my “useful field of view”, my visual field. It is a very important component of the program.

After the age of 50: rapid decline

The importance of the visual field when driving is obvious to us all. After the age of 50, there is a rapid decline in

• Our sensory vision, resulting in a reduction of visual acuity and sensitivity to contrast. This is obvious to me in terms of night driving.

• Our perception of distance and space: the use of stereoscopic cues i.e.the smallest difference in the images presented to the two eyes.

• Our visual field sensitivity: i.e. everything that (at a given time) causes light to fall onto the retina. This input is processed by the visual system in the brain which computes the visual field as we see it.

Night driving

At night we have poorer colour discrimination and with age we don’t pick up contrast like we used to.  The presence of head-lights, street lighting and reflective road markings  moderate the experience of driving at night but visual processing still remains impaired compared with daytime. Research shows that drivers are generally unaware of the visual limitations of driving at night as this extrinsic lighting allows them to continue to see road signs and steer their vehicles effectively. At night, older drivers need to be closer to road signs, and view them for longer, before they are recognized.

The outcome is longer reaction times, resulting in longer stopping distances.

Much of this information has been operationalised into the Posit Science Insight program activities. It includes long term training in speed of processing, memory, visual acuity, contrast sensitivity, expansion of UFOV. There is also instruction about the visual field and the visual processing system plus where to apply this training and knowledge to everyday driving and living. (What is called  the  ‘top-down’ component.)

Also knowledge is power. So perhaps we can add confidence….?

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Visual function and fitness to drive: British Medical Bulletin Advance Access published August 20, 2008

http://bmb.oxfordjournals.org/cgi/content/short/87/1/163