Having a blood alcohol level just under the legal limit of 0.08 — typically just one drink — can still affect the driving abilities of older adults, according to a new University of Florida (UF) study.
Sara Jo Nixon, Ph.D., a professor in the departments of psychiatry and psychology at the University of Florida and doctoral candidate Alfredo Sklar conducted the study to see whether non-intoxicating levels of alcohol would affect the driving skills of 72 participants who fell into one of two age groups: ages 25 to 35 and ages 55 to 70.
The study, published in the journal Psychopharmacology, is the latest in a series of studies by Nixon and her team that looks at how even moderate doses of alcohol affect aging adults.
At the beginning of the study, all subjects (completely sober) were given a simulated driving test. Participants — staring straight ahead at a large computer monitor — felt as though they were driving down a winding three-mile stretch of country road.
Two more monitors were placed on either side, mimicking the side windows of a car and showing the drivers what they would see in their peripheral vision. Driving sounds were played through a stereo system. Occasionally, the drivers would encounter an oncoming car, but they did not encounter other distractions.
“There wasn’t even a cow,” said Nixon, who also is co-vice chair and chief of the division of addiction research in the department of psychiatry in the UF College of Medicine and UF’s Evelyn F. and William L. McKnight Brain Institute.
The driving test assessed the participants’ ability to stay in the center of their lane and maintain a constant speed. Researchers also noted how rapidly the subjects moved their steering wheel.
Later, the participants were divided in smaller groups. The first group was given a placebo — a diet lemon-lime soda spritzed with an insignificant amount of alcohol to mimic the experience of drinking alcohol. A second group’s drink was strong enough to produce a 0.04 percent breath alcohol level, and a third group’s drink gave them a breath alcohol level of 0.065 percent — still below the federal legal level for drinking of 0.08.
Participants then completed the same driving task they had performed while sober. Researchers timed the task so participants’ alcohol levels were declining to imitate a situation in which a person would have a drink with dinner and then drive home.
For the older drivers, even the small, legal levels of intoxication affected their driving skills.
In the younger age group, however, alcohol consumption did not affect their measured driving skills at all — a finding that Nixon called a “bit surprising.” She warned that although there was no difference in the laboratory, this does not necessarily mean that their driving wouldn’t be affected in real life.
Nixon noted that the laboratory setting was simplified compared to real-world driving and that the current data doesn’t address potential problems in more complex environments.
Source: University of Florida