Methylphenidate Improved Driving Performance in Adults
Methylphenidate improved driving performance in adults by reducing lane weaving and speed variation, according to results from a recent randomized controlled trial published in the Journal of Psychopharmacology.
“This study demonstrated that an acute 10 mg dose of methylphenidate demonstrated protective effects against performance degradation commonly observed during prolonged, monotonous driving, evidenced by improvements in vehicle control and speed maintenance relative to placebo,” authors noted. “The limited changes in broader ocular metrics such as gaze transition entropy (GTE) and stationary gaze entropy (SGE) suggest that while methylphenidate enhances specific aspects of cognitive function, it does not universally improve visual scanning efficiency.”
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In this study, 25 licensed, healthy adults (mean age = 33.5 ± 7.8 years, 64% male) completed two 40-minute simulated highway drives 1 week apart, with their simultaneous eye movements being monitored using a proprietary automotive-grade driver monitoring system. Researchers assessed driving performance using the standard deviations of lateral position, speed, and steering variability. Visual scanning efficiency was assessed using ocular metrics, fixation duration and rate, gaze transition entropy, and stationary gaze entropy.
Methylphenidate significantly improved participants’ driving performance by reducing lane weaving and speed variation, especially in the last half of the simulation. Though researchers saw a significant reduction in fixation duration, all the other ocular metrics stayed stable. Participants reported no significant differences in perceived drug effects. Standard deviation of lateral position (SDLP) was reduced after methylphenidate administration compared to placebo, meaning participants were weaving less while driving (mean difference = −1.33, p = 0.001, 95% CI = −0.52 to −2.14). At 40 minutes, standard deviation of speed (SDS) decreased with methylphenidate compared to placebo, indicating improved speed maintenance (mean difference = −0.56, p = 0.014, 95% CI = −0.10 to −0.123). There was also a notable reduction in starting wheel movements after methylphenidate administration compared to placebo mean difference = −0.0001, p = 0.037, 95% CI = −0.0003 to −0.00001).
Authors noted that, given the driving simulation was not complex and was repeated, “demands on gaze behavior, the necessity for frequent and varied eye movements may be low” and there may have been a “ceiling effect” on the repeated trip. Authors also pointed out that a low, acute dose of methylphenidate was used, so results may not properly reflect what changes would look like in patients taking higher or more frequent doses.
“There is a clear need for further research in this area, particularly studies aimed at identifying more pronounced alterations in ocular behavior caused by methylphenidate and other psychostimulants,” authors concluded. “Considering the broad range of effects elicited by this class of drugs, it is important for research to clearly outline the spectrum of these effects such that thresholds can be established to enable detection of impairment by monitoring technologies and reduce safety risk.”
