Undoubtedly, such decrements would severely degrade operational effectiveness. The deficits observed were greater than those typically produced by alcohol intoxication, treatment with sedating drugs, or clinical hypoglycemia. Relatively simple cognitive functions such as reaction time and vigilance were significantly impaired, as were more complex functions, including memory and logical reasoning. In both groups, during stressful combat-like training, every aspect of cognitive function assessed was severely degraded compared with baseline, pre-stress performance. We administered a variety of identical, computer-based cognitive tests to both groups. In the other study, participants were younger, mostly enlisted, trainees with only 3 yr of military experience on average, in training to determine if they would qualify for an elite U.S.

In one study, subjects were officers, with an average 9 yr of military service, who were members of an elite U.S. These studies were conducted in different environments with two different types of military volunteers. Our laboratory had several unique opportunities to study cognitive function in warfighters engaged in exercises designed to simulate the stress of combat. However, little objective information is available to confirm these observations.

Anecdotal reports from military conflicts suggest cognitive performance and mood are severely degraded by the stress of combat.

The fog of war