Cognitive impairment of acute mountain sickness and acetazolamide.

In a trial to assess the cognitive impairment attributable to benign acute mountain sickness (AMS) and to acetazolamide, six women and five men, 20-35 years old, ascended from sea-level to 3600 m in 36 h and were assessed for deterioration in performance on psychological tests. Of five sex-matched pairs with a mean age difference of 3.4 years (S.D. +/- 4.4 years), one member took slow-release acetazolamide 500 mg daily and one placebo on a double-blind basis during the ascent and again for an identical course at low altitude 32-38 d later. The unmatched woman took placebo during ascent. Before, during, and after each drug course each subject performed an Environmental Symptom Questionnaire (ESQ) and a psychological test battery consisting of trail-making, paced auditory serial addition test (PASAT), letter-digit code, dual-task cancellation and subtraction, and memory subtests. On ascent, ESQ score deteriorated by an average of 62 points in placebo subjects compared with 32 in acetazolamide subjects (p = 0.055). Deterioration in the psychological test battery was only significant in the PASAT (p less than 0.05) and memory (p less than 0.01) subtests of subjects taking placebo. For those taking acetazolamide, no test showed significant impairment, suggesting it had no detectable cognitive impairment at this dose.