title: Acute hyperammonaemia induces a sustained decrease in vigilance, which is modulated by caffeine.
abstract: Hyperammonaemia is observed after prolonged, intense exercise, or in patients with hepatic failure. In the latter, it is associated with a set of neurological and psychiatric abnormalities termed hepatic encephalopathy.
  
  
  OBJECTIVE
  1. to measure vigilance in a condition of induced hyperammonaemia; 2. to assess whether caffeine modulates the effects of hyperammonaemia on vigilance, if any. Ten healthy volunteers (28.5 ± 5 years; 5 males) underwent three experimental sessions consisting of two-hourly measurements of capillary ammonia, subjective sleepiness (Karolinska Sleepiness Scale) and vigilance (Psychomotor Vigilance Task, PVT), in relation to the intake of breakfast (+/-coffee), an amino acid mixture which induces hyperammonaemia (amino acid challenge; AAC), and AAC+coffee (only for participants who had coffee with their standard breakfast). The AAC resulted in: 1. the expected increase in capillary ammonia levels, with highest values at approximately 4 h after the administration; 2. a significant increase in subjective sleepiness ratings; 3. a sustained increase in PVT-based reaction times. When caffeine was administered after the AAC, both subjective sleepiness and the slowing in RTs were significantly milder than in the AAC-only condition. In conclusion, acute hyperammonaemia induces an increase in subjective sleepiness and a sustained decrease in vigilance, which are attenuated by the administration of a single espresso coffee.
authors: Department of Medicine, University of Padova, Via Giustiniani, 2, 35128, Padova, Italy.
authors: E P
authors: EP
authors: Casula
authors: P S
authors: PS
authors: Bisiacchi
authors: M
authors: M
authors: Corrias
authors: S
authors: S
authors: Schiff
authors: C
authors: C
authors: Merkel
authors: P
authors: P
authors: Amodio
authors: S
authors: S
authors: Montagnese
mesh_terms: D000208:Acute Disease; D000328:Adult; D000596:Amino Acids / Q000633:toxicity; D001143:Arousal / Q000187:drug effects*; D062408:Breakfast; D002110:Caffeine / Q000627:therapeutic use*; D002196:Capillaries; D003069:Coffee; D006801:Humans; D022124:Hyperammonemia / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy / Q000523:psychology*; D008297:Male; D008499:Medical Records; D011597:Psychomotor Performance / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000596:Amino Acids; D003069:Coffee; D002110:Caffeine