ASU Research E-Magazine: More Nasty News About Nicotine

Tobacco users who think they perform better after a cigarette or a pinch of chewing tobacco should think again.

New research findings indicate that the nicotine in tobacco products reduces an individual’s ability to perform and learn tasks that require complex visual and motor skills.

Scientists already know that nicotine use reduces dopamine release in the basal ganglia, the area of the human brain that controls movement, says George Stelmach, ASU professor of exercise science and physical education. Stelmach is completing a three-year study designed to test how nicotine affects human movement. Early results appeared in the November 1999 issue of the journal Nicotine & Tobacco.

During their initial experiments, Stelmach and ASU graduate students found that tobacco users exhibited a slower learning curve. Their movements were slower and more irregular than non-tobacco users.

“Our results suggest that tobacco use on the job can reduce an individual’s capacity to learn new visual-motor mapping and adapt his or her performance to new visual feedback,” says Jose Contreras-Vidal, now at the University of Maryland.

Study participants were tested individually for about two hours on three separate tasks. They were asked to draw the straightest possible path as quickly as possible from a central point on a computer screen to a target that lit up in one of four different positions on the edges of the screen.

Participants included 10 tobacco users and 11 non-users. The users abstained from tobacco for at least eight hours before being tested. After the first test, no differences were found between the two groups.

Tobacco users then were given a pinch of smokeless tobacco immediately before the second test. The feedback screen was also rotated by 45 degrees. Tobacco users performed this task much worse than non-users with regard to accuracy and smoothness of movement.

Non-users greatly reduced the jerkiness of their movements between sessions one and two, while tobacco users did not.

The third test was identical to the first. The intent was to measure participants’ ability to readapt following the 45-degree rotation of targets in the second session. Non-users continued to improve the smoothness of their movements. The smokeless tobacco users did not.

“These findings provide one more piece of evidence that nicotine is affecting users in ways not previously known,” Stelmach says. “We now have other data that shows nicotine intake affects the way complex movement (involving several joints) is controlled.”

ASU scientists are now studying how nicotine affects the brain’s ability to perform simple tasks.—Lynette Summerill