Cognitive Difference Associated with High-Altitude Flying in Pilots (P01.052)

OBJECTIVE: Extreme high-altitude exposure incites change in general cognitive functioning, cognitive processing speed and memory. BACKGROUND: Extreme high-altitude exposure places physiologic stress on the pilot9s central nervous system. Some pilots experience neurologic decompression sickness, exhibiting a variety of neurologic symptoms, including cognitive difficulties. Previous work has demonstrated the presence of subcortical white matter change in high-altitude pilots even in the absence of clinical symptoms. We hypothesize cognitive networks are impacted within an individual with extreme hypobaric exposure in the absence of clinical symptoms. DESIGN/METHODS: The authors obtained cognitive testing on 48 high-altitude (U2) military pilots before pilot training and 85 after extreme hypobaric exposure. Sixty non-exposed military pilots (AFP) served as controls. Baseline and current Multidimensional Aptitude Battery II (MAB-II) and MicroCog assessments were compared between U2 and AFP groups using a two-tailed t-test. Baseline versus current MAB-II and Microcog assessments were compared within the same pilot, using paired t-test. RESULTS: Pilots in both cohorts demonstrated very high performance (>1SD above population means). At baseline, no significant difference on the MicroCog in global cognitive functioning or proficiency or information processing accuracy was noted. Both groups of pilots demonstrated an improvement when comparing their individual baseline to their individual current results. Current testing on U2 versus AFP demonstrated significant differences in general cognitive proficiency (p=0.022), information processing accuracy (p=0.026), reasoning (p=0.001), and memory (0.006). No group differences were observed in full scale IQ, verbal IQ, or performance IQ on baseline or current MAB-II. CONCLUSIONS: Extreme hypobaric exposure is associated with a mild difference in general cognition, processing accuracy, reasoning and memory compared to AFP controls not exposed to extreme altitudes. Although there is a statistically significant change, U2 pilots continue to perform highly on cognitive assessments. Additional study is underway to explain the mechanism of this difference. Disclosure: Dr. Rasmussen has nothing to disclose. Dr. Tate has nothing to disclose. Dr. Kochunov has nothing to disclose. Dr. Sherman has nothing to disclose. Dr. McGuire has nothing to disclose.