title: GABA levels are decreased after stroke and GABA changes during rehabilitation correlate with motor improvement.
abstract: OBJECTIVE
  γ-Aminobutyric acid (GABA) is the dominant inhibitory neurotransmitter in the brain and is important in motor learning. We aimed to measure GABA content in primary motor cortex poststroke (using GABA-edited magnetic resonance spectroscopy [MRS]) and in relation to motor recovery during 2 weeks of constraint-induced movement therapy (CIMT).
  
  
  METHODS
  Twenty-one patients (3-12 months poststroke) and 20 healthy subjects were recruited. Magnetic resonance imaging structural T1 and GABA-edited MRS were performed at baseline and after CIMT, and once in healthy subjects. GABA:creatine (GABA:Cr) ratio was measured by GABA-edited MRS. Motor function was measured using Wolf Motor Function Test (WMFT).
  
  
  RESULTS
  Baseline comparison between stroke patients (n = 19) and healthy subjects showed a significantly lower GABA:Cr ratio in stroke patients (P < .001) even after correcting for gray matter content in the voxel (P < .01) and when expressing GABA relative to N-acetylaspartic acid (NAA; P = .03). After 2 weeks of CIMT patients improved significantly on WMFT, but no consistent change across the group was observed for the GABA:Cr ratio (n = 17). However, the extent of improvement on WMFT correlated significantly with the magnitude of GABA:Cr changes (P < .01), with decreases in GABA:Cr ratio being associated with better improvements in motor function.
  
  
  CONCLUSIONS
  In patients 3 to 12 months poststroke, GABA levels are lower in the primary motor cortex than in healthy subjects. The observed association between GABA and recovery warrants further studies on the potential use of GABA MRS as a biomarker in poststroke recovery.
authors: Aarhus University, Aarhus, Denmark Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Hammel, Denmark jbli@cfin.au.dk.
authors: Jakob Udby
authors: JU
authors: Blicher
authors: McGill University, Montreal, Quebec, Canada.
authors: Jamie
authors: J
authors: Near
authors: Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Hammel, Denmark.
authors: Erhard
authors: E
authors: Næss-Schmidt
authors: Oxford University, Oxford, UK.
authors: Charlotte J
authors: CJ
authors: Stagg
authors: Oxford University, Oxford, UK.
authors: Heidi
authors: H
authors: Johansen-Berg
authors: Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Hammel, Denmark.
authors: Jørgen Feldbæk
authors: JF
authors: Nielsen
authors: Aarhus University, Aarhus, Denmark.
authors: Leif
authors: L
authors: Østergaard
authors: Aarhus University, Aarhus, Denmark.
authors: Yi-Ching Lynn
authors: YC
authors: Ho
mesh_terms: D000328:Adult; D000368:Aged; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009044:Motor Cortex / Q000737:chemistry*; D020127:Recovery of Function; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: GABA; constraint-induced movement therapy; magnetic resonance spectroscopy; rehabilitation; stroke