Apnea Diving: Long-Term Neurocognitive Sequelae of Repeated Hypoxemia

ABSTRACT

This article examines the neurocognitive sequelae of repeated exposure to hypoxemia in apnea (breath-hold) divers. A brief review of the literature on the physiological and neurological adaptations involved in the “human diving reflex” is presented. The results from a neuropsychological investigation of N = 21 elite apnea divers are evaluated. Standard neuropsychological tests, with known sensitivity to mild brain insults, included speed of visuo-motor responding, speed of language comprehension, response inhibition, and visual and verbal attention and recall tasks. Results indicated that the breath-hold divers performed tasks within the average range compared to norms on all tests, suggesting that 1–20 years of repeated exposure to hypoxemia including multiple adverse neurological events did not impact on performance on standard neuropsychological tasks. The results are discussed in relation to implications for clinical conditions such as sleep apnea, respiratory disorders, altitude sickness, and recreational apnea activities.

Notes

Note. P_AO₂ = Alveolar oxygen pressure.

^a Verbal production error. A fully conscious Canadian diver emerged post long-duration breath-hold and had meant to say “Man, that was ugly.” Instead, the neologism “Mooglie” was uttered and has been adopted by the team to describe any “uncomfortable” breath-hold.

^a Dive depth in meters.

^b Static time in minutes.

^c LMC-Loss of motor control. Divers reported their approximate number of “sambas.”

^d LOC-Loss of consciousness from “shallow water blackout.”

^e Total number of negative neurological events in life, includes previous concussions, head injury, and dive-related accidents.

Note. All variables have been rescaled such that a low Z score reflects poorer performance.