A clinical method of evaluating simple reaction time and reaction accuracy is sensitive to a single dose of lorazepam.

RATIONALE

Benzodiazepines are useful and commonly prescribed. Unfortunately, they are associated with subtle but functionally significant neurocognitive side effects that increase the risk of motor vehicle accidents and falls.

OBJECTIVE

The objective of this study was to determine whether clinically feasible measures of simple reaction time and reaction accuracy are sensitive to a single dose of lorazepam.

METHODS

Using a randomized, double-blind, crossover design, 26 healthy adults (13 women; age = 26.9 ± 8.2 yr) were given 1.0 mg lorazepam or placebo 90 minutes prior to two data collection sessions. Participants completed simple and reaction accuracy tasks using a standardized "ruler drop" testing paradigm during each session. Outcomes were mean and variability of simple reaction time and reaction accuracy, which evaluates a participant's ability to catch the device solely on the random 50% of trials that lights affixed to it illuminate on release. Reaction accuracy requires a go/no-go decision within 420 ms before the falling device strikes the floor.

RESULTS

As compared with placebo, lorazepam increased simple reaction time variability (range = 43 ± 18 vs. 60 ± 23 ms, respectively; = 0.004 and standard deviation = 14.6 ± 5.7 vs. 19.7 ± 7.3 ms, respectively; = 0.006) and decreased reaction accuracy (90 ± 7% vs. 84 ± 11%, respectively; = 0.010).

CONCLUSION

Given prior work demonstrating associations between simple reaction time and reaction accuracy and functional outcomes such as self-protection, response to perturbations, and fall risk, these clinically available measures may have a role in identifying subtle, functionally significant cognitive changes related to short-term benzodiazepine use.