European isolation and confinement study. Mental performance.

Six EMSInauts were confined for 28 days in a hyperbaric chamber complex at a low overpressure. During this period they were repeatedly given four different standard mental performance tests: (1) Operational Test of sustained attention vigilance; (2) short-term memory; (3) visual reaction time; and (4) cognitive evoked brain potentials (N100 and P300). The aim of the study was to determine whether there were any general or specific effects on mental performance during the isolation period. For the simple mental performance tests (operational test and visual reaction time), a distinct learning effect over the 28 days of isolation could be detected. On the more cognitive demanding tasks such as in the short-term memory test, patterns of impairment were found. Of the cognitive evoked brain potentials recorded, the noncognitive N100 wave latency was unchanged throughout the isolation period. The P300 wave latency, related to cognitive functioning, showed lower values in the middle and higher values at the end of the isolation period, compared with the pre-isolation values. Although a few individual, transient impairments of function were noticed in the more demanding tests, it is concluded that the mental performance of the six EMSInauts appeared to remain basically unchanged throughout the isolation phase, both at the group level and the individual level.