Odor identification ability predicts changes in symptoms of psychopathology following 56 H of sleep deprivation

A person's ability to identify odors provides an index of the functional integrity of the brain's prefrontal cortex. Some evidence suggests that the functional activity of the prefrontal cortex, when well rested, may predict individual differences in the ability to sustain performance when subsequently sleep deprived. It was hypothesized that odor identification accuracy, when rested would predict the vulnerability to sleep deprivation-mediated elevations of affective symptoms of psychopathology, as measured on the Personality Assessment Inventory (PAI). Twenty-two healthy volunteers completed the University of Pennsylvania Smell Identification Test (SIT) and the PAI when rested. After 56 h of continuous wakefulness, participants were re-administered the PAI. Poorer odor identification at baseline correlated with increased symptoms of depression and borderline negative relationships. In contrast, higher SIT scores correlated with increased manic irritability. Results suggest that better olfactory identification in the well-rested state (a putative index of orbitofrontal cortex integrity) predicts affective stability during subsequent sleep deprivation.