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Stanford Report, July 12, 2000

Exposure therapy explored for treatment of driving phobias  


Cruising in a convertible across the Golden Gate Bridge is a scene made famous in the movie "Interview with the Vampire," and for many visitors it embodies California's automobile-centric lifestyle. But for people with a driving phobia, merging onto a freeway filled with fast-moving traffic can induce an anxiety attack and confronting a bridge can be their worst nightmare.

Marcia Feitel was one of those people. A 44-year-old software engineer, she was terrified at the prospect of driving faster than 40 miles per hour and so avoided freeways at all cost. "I didn't learn to drive until I was 28, so when I finally did learn there was a lot of anxiety associated with going fast," Feitel said. She was also upset by roads that bank as they round a corner and by tire skid marks on the road ­ which reinforced her belief that the streets are rife with dangerous drivers. "When I saw the road was banked, it was very stressful not to slow down," Feitel said. "And I was not happy to see skid marks on the road. Those were things that triggered a burst of fear in me."

So Feitel enrolled in a Stanford study designed to monitor the emotions and bodily reactions of people who are afraid to drive. The study is designed to gauge the effectiveness of exposure therapy as a means to treat the condition. Exposure therapy involves entering the avoided situation and confronting the anxiety, and commonly is used to treat phobias such as fear of spiders or flying in an airplane.

"The study is designed to overcome the phobia of driving a car," said Georg Alpers, psychologist and visiting researcher in the department of psychiatry and behavioral sciences. Alpers is conducting the study with research associate Frank Wilhelm, PhD, and Walton Roth, MD, professor of psychiatry and behavioral sciences and Chief of the Psychiatric Consultation Service at the Veteran's Affairs Palo Alto Health Care System.

Study participants agree to several treatment sessions whereby they drive in a variety of typical situations. The route is designed specifically for each patient, who typically spends 60 to 90 minutes on the road in each of the three sessions. Each trip focuses on one previously avoided driving situation.

For her first session, Feitel was asked to drive onto Highway 101. "I was almost sick with fear," she said. "I was never aware that it's possible to get that frightened. It was all I could do to drive back to work afterwards." By the third session, she was able to move to the fast lane and overtake another vehicle. "That was viewed as progress," she said.

Before the trip, the driver is outfitted with an array of sensors that monitor heart rate, breathing and skin conductance, the last of which gives the researcher an indication of how much the subject is sweating. Information is collected continuously and captured via a portable recorder attached to the waist. The person's saliva is sampled at various times to detect any changes in the level of stress hormones, and the gas mixture of the air the person exhales is also monitored. These physical measurements are then correlated with the person's subjective reports of the level of anxiety experienced throughout the drive. The researcher then compiles the physical and psychological data to reach an overall assessment of the anxiety level experienced by each patient.

"We monitor the physiology in the lab and during the driving," said Alpers. The data collected from each anxious subject is compared to the same data collected from age- and gender-matched control subjects.

According to Alpers, fear of driving is especially suited to physiological evaluation in real life situations because, unlike many agoraphobic situations e.g. walking in crowded places, driving entails only minimal exercise. The relative lack of physical activity necessary to drive a car means that any changes in heart and respiration rates reflect the patient's response to the anxiety-provoking situation rather than changes induced by exercise. To calculate a base-line level for each patient, measurements of all parameters also are made when the person is at rest and when they are exercising on a stationary bicycle.

Preliminary results from the first twenty-one patients, who are all women, show that heart rate and the subjective anxiety rating were lower on the inbound, or return, leg of the journey than on the outbound leg. Both values also decreased over the three sessions suggesting that patients felt less anxious after completion of the study.

Measurements for individual patients found that the level of exhaled carbon dioxide decreased and the heart rate increased when the driver confronted an anxiety-provoking situation, such as crossing a bridge. These preliminary results have led Alpers to conclude that subjects with a driving phobia subconsciously over-prepare for emergency physical activity ­ their body reacts by inhaling more oxygen and exhaling more carbon dioxide than they currently need, which is defined as hyperventilation. For some people, the sensations resulting from hyperventilation make them feel even more anxious.

Feitel says that the exposure itself is empowering. "The fact that you're doing something is positive reinforcement," she said. "A lot of my fear had to do with doing the wrong thing and causing injury to myself or others. The study got me believing that I could make some improvement in how I felt ­ I went from being ready to collapse, to just being kind of edgy. And once I actually got onto the highway, the other things that I was afraid of just didn't happen."

Alpers is still recruiting volunteers for the study. Control subjects are paid $15 per hour for each 4-hour driving session. For further information, call (650) 493-5000 extension 65640. SR