Acute hyperammonaemia induces a sustained decrease in vigilance, which is modulated by caffeine

• Published in: Metabolic brain disease Vol. 30; no. 1; pp. 143 - 149
• Main Authors: Casula, E. P., Bisiacchi, P. S., Corrias, M., Schiff, S., Merkel, C., Amodio, P., Montagnese, S.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-02-2015; Springer Nature B.V
• Subjects: Acute Disease; Adult; Amino Acids - toxicity; Arousal - drug effects; Biochemistry; Biomedical and Life Sciences; Biomedicine; Breakfast; Caffeine - therapeutic use; Capillaries; Coffee; Humans; Hyperammonemia - blood; Hyperammonemia - chemically induced; Hyperammonemia - drug therapy; Hyperammonemia - psychology; Male; Medical Records; Metabolic Diseases; Neurology; Neurosciences; Oncology; Psychomotor Performance - drug effects; Research Article; Young Adult; Vigilance; Hyperammonaemia; Sleepiness; Caffeine
• ISSN: 0885-7490; 1573-7365
• DOI: 10.1007/s11011-014-9590-8

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. The aims of our study were: 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.