Driving with Your Brain

by Guy McKhann, M.D.

August 6, 2009

Any physician who deals with elderly patients has run up against the problem of when a person should stop driving. On numerous occasions I have had members of a family tell me that they are worried about an elderly relative’s driving but are afraid to bring up the subject, and ask: Will I do it?

Driving is so essential to functioning in our society that removing that privilege can result in social isolation, as one no longer can get to the store, visit friends or relatives, or participate in volunteer activities. Taking away a driving license forces a degree of dependence upon a person, which isn’t necessarily a good thing for older people.

The Boston Globe article “Your Brain in Drive” by Drake Bennett is an excellent discussion of the issues involved. If there is one thing we have learned from the study of cognitive processes in the elderly, it is that there is enormous variability. Some people in their 90s function remarkably well. Others in their 60s have already begun to lose their cognitive abilities. Clearly, it is not just a question of age. The simple bureaucratic solution of having an upper age for driving—as we have a lower age—would make no allowance for this variability.

The 96-year-old mother of one of my colleagues has remarkably intact cognitive functions. (Another sharp 96-year-old, Emma Shulman, is profiled in the New York Times story “She Knows a Thing or Two about Aging.”) At the age of 93 this mother bought a Toyota Prius, a hybrid car, so that she could participate in the green movement. In the last election, she drove to the local Democratic headquarters so she could volunteer to drive older voters to the polls. Some volunteers suggested that she man the phones instead, but she would have none of that! On the other hand she restricts her driving to when she feels safe: not at night, not on stormy days, not on major highways. Ruling this woman off the roads would be an injustice. But someday she should stop. How do you tell when that time has arrived?

Regulations regarding driving are determined at a state level. About one-third of states have expanded requirements for the elderly. As mentioned in the Globe article, there are a number of programs that evaluate older people for the skills required for driving. One of the most successful is the DriveWise program at the Beth Israel Deaconess Hospital in Boston, which evaluates such things as vision, reaction times, attention, judgment and ability to multitask, that is, to focus on more than one task at a time. As we age, our brains do change, and one of the normal changes is that our ability to multitask decreases. Elderly drivers need to pay attention on the road and not use the phone—especially dialing numbers. (This is probably true for younger drivers as well, but is a much harder sell.)

The brain as a driver

A new area of neurosciences has been quietly developing: Brain-Machine Interfaces (BMI). This field involves the study of how the electrical activity of brain neurons can be used to control the activities of a robot, such as a prosthetic arm. The first step in the process is to develop a recording device that receives bran signals. In animal studies, implantable recorders are used. Because of the risks involved, implanted recording devices are only used in humans under special circumstances, such as mapping functions in the brain prior to surgery for epilepsy. These short-term recordings can give scientists the “proof of principle” that will allow for further research, but the devices themselves are not ready for long-term use. One of the active areas of research is to develop devices that utilize less-risky external recorders, such as electroencephalograms (EEG) or magnetoencephalograms (MEG).

In the Scientist article “Brain (Minus Machine) Interface” by Edyta Zielinska, scientists at University of California, Berkeley report that a monkey’s brain can develop a stable motor map—a stable interconnection of neurons—to move a robotic device. As we develop our ability to control our motor movements, we develop such stable maps so that movements become automatic. You don’t think about your movements as you walk, ride a bike, hit a tennis ball or play the piano. Rather, you activate a series of neurons that have learned to make the movement. This study indicates it is possible to take advantage of this ability of the brain when the moving part is not an arm or leg, but an artificial limb or computer cursor. Thus, in this aspect of the brain-machine interface, the brain is developing and using mechanisms similar to those at work during normal movement.

There are still problems to be solved in the area. Not least is to establish some form of sensory feedback to make the brain aware of what the prosthesis is doing. If you close your eyes and reach for your coffee cup, you hand assumes various positions depending on what part you touch. That sensory feedback is an essential part of movement control. As the output side of brain-machine interfaces are developed, so must the input side.

Just think: as this field advances, couch potatoes will not even have to push a button to change channels on the TV. Hopefully, there will also be a monitoring device to shut things down after too much time on the couch, allowing you to get up and exercise.