title: Short latency afferent inhibition: a biomarker for mild cognitive impairment in Parkinson's disease?
abstract: BACKGROUND
  Mild cognitive impairment in Parkinson's disease (PD) is common and predicts those at risk of dementia. Cholinergic dysfunction may contribute to its pathophysiology and can be assessed using short latency afferent inhibition.
  
  
  METHODS
  Twenty-two patients with PD (11 cognitively normal; 11 with mild cognitive impairment) and 22 controls participated. Short latency afferent inhibition was measured by conditioning motor evoked potentials, which were elicited by transcranial magnetic stimulation of the motor cortex with electrical stimuli delivered to the contralateral median nerve at varying interstimulus intervals.
  
  
  RESULTS
  There was no significant difference between cognitively normal PD and controls for short latency afferent inhibition (62.8±30.3% vs. 55.7±21.7%; P=0.447). The PD-mild cognitive impairment group had significantly less inhibition (88.4±25.8%) than both cognitively normal PD (P=0.021) and controls (P=0.01).
  
  
  CONCLUSIONS
  Cholinergic dysfunction occurs early in those with PD-mild cognitive impairment. Short latency afferent inhibition may be a useful biomarker of increased risk of dementia in PD patients. © 2013 Movement Disorder Society.
authors: Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK. alison.yarnall@ncl.ac.uk
authors: Alison J
authors: AJ
authors: Yarnall
authors: Lynn
authors: L
authors: Rochester
authors: Mark R
authors: MR
authors: Baker
authors: Rachel
authors: R
authors: David
authors: Tien K
authors: TK
authors: Khoo
authors: Gordan W
authors: GW
authors: Duncan
authors: Brook
authors: B
authors: Galna
authors: David J
authors: DJ
authors: Burn
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology* / Q000473:pathology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology; D010300:Parkinson Disease / Q000150:complications*; D011930:Reaction Time / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation
keywords: Parkinson's disease; acetylcholine; mild cognitive impairment; neurophysiology; transcranial magnetic stimulation