The role of blood glucose availability and fatigue in the development of cognitive impairment during combat training.
BACKGROUND
The aim of this study was to determine whether inadequate nutrition would produce a reduction in the blood glucose concentration and impair cognitive function.


METHODS
Energy intake, blood glucose, and cognitive function were measured in 18 male subjects during a 4-d military field exercise. Baseline measures of fasting blood glucose, body mass, cognitive function, and mood were taken before the start of combat training. Measurements of blood glucose, cognition, and well-being were then repeated during every subsequent 24 h period. Activity levels were monitored continuously using wrist-worn activity monitors.


RESULTS
Subjects experienced an increase in symptoms relating to hypoglycemia after 24 h in the field (p < 0.01), vigor decreased (p < 0.001), and fatigue increased (p < 0.001). After 48 h, subjects reported feelings of depression (p < 0.05), anger (p < 0.01), and confusion (p < 0.001). Delayed memory recall was significantly impaired after 48 h (p < 0.05), and there was a decrease in vigilance (p < 0.01). Between 48 and 72 h, there was a decrease in immediate memory recall (p < 0.05). Delayed memory recall and vigilance remained impaired, but did not deteriorate further. When subjects were extracted from the field after 96 h, nude BM had decreased by 2% (p < 0.05).


CONCLUSIONS
Although it was possible to reproduce the symptoms and cognitive impairment associated with hypoglycemia, there was no change in blood glucose concentration throughout the 4-d period. The impairment in cognitive function is likely to have been the result of significant sleep deprivation.
Owen
Gail
G
Centre for Human Sciences, QinetiQ, Farnborough, Hampshire, UK. Gail.Owen@Unilever.com
Turley
Helen
H
Casey
Anna
A
D000328:Adult; D000339:Affect; D001143:Arousal; D001786:Blood Glucose; D031204:Caloric Restriction / Q000009:adverse effects*; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D005221:Fatigue / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D007003:Hypoglycemia / Q000503:physiopathology; D008297:Male; D011939:Mental Recall; D008889:Military Personnel
D001786:Blood Glucose