title: Caffeine restores regional brain activation in acute hypoglycaemia in healthy volunteers.
abstract: OBJECTIVE
  Caffeine enhances counterregulatory responses to acute hypoglycaemia. Our aim was to explore its effects on cortical function, which are not known at present.
  
  
  METHODS
  Regional brain activation during performance of the four-choice reaction time (4CRT) at different levels of complexity was measured using functional magnetic resonance imaging (fMRI) at euglycaemia (5 mmol/l) and hypoglycaemia (2.6 mmol/l) in the presence and absence of caffeine in six healthy right-handed men.
  
  
  RESULTS
  During hypoglycaemia, caffeine enhanced adrenaline responses to hypoglycaemia (2.5 +/- 0.7 nmol/l to 4.0 +/- 1.0 nmol/l, P = 0.01) and restored the brain activation response to the non-cued 4CRT, the linear increases in regional brain activation associated with increased task complexity and the ability to respond to a cue that were lost in hypoglycaemia alone.
  
  
  CONCLUSIONS
  Caffeine can sustain regional brain activation patterns lost in acute hypoglycaemia, with some restoration of cortical function and enhanced adrenaline responsiveness. A methodology has been established that may help in the development of therapies to protect against severe hypoglycaemia in insulin therapy for patients with diabetes and problematic hypoglycaemia.
authors.affiliation: Centre for Diabetes and Endocrinology, and Diabetes Research Group, King's College London School of Medicine, London, UK. m.rosenthal@ucl.ac.uk
authors.forename: M J
authors.initials: MJ
authors.lastname: Rosenthal
authors.forename: D
authors.initials: D
authors.lastname: Smith
authors.forename: L
authors.initials: L
authors.lastname: Yaguez
authors.forename: V
authors.initials: V
authors.lastname: Giampietro
authors.forename: D
authors.initials: D
authors.lastname: Kerr
authors.forename: E
authors.initials: E
authors.lastname: Bullmore
authors.forename: M
authors.initials: M
authors.lastname: Brammer
authors.forename: S C R
authors.initials: SC
authors.lastname: Williams
authors.forename: S A
authors.initials: SA
authors.lastname: Amiel
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects*; D006801:Humans; D007003:Hypoglycemia / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine