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Keywords:

  • Parkinson's disease;
  • dementia;
  • neurophysiology;
  • Alzheimer's disease;
  • Parkinson's disease dementia

Abstract

Background:

Cortical cholinergic deficiency occurs in Parkinson's disease (PD) and is more severe in PD dementia (PDD). Short-latency afferent inhibition (SAI) can be used as an in vivo test for the evaluation of the cholinergic circuit in the cerebral motor cortex.

Methods:

SAI and neuropsychological profile were studied in nondemented PD, PDD, Alzheimer's disease (AD) patients, and age-matched controls.

Results:

SAI was significantly impaired in AD cases (94.7 ± 6.2 versus 55.5 ± 4.0; P < 0.0001). In PD patients, it was not different from controls (61.4 ± 5.8 versus 55.5 ± 4.0; P = 0.412). PDD cases demonstrated a significant impairment in SAI (91.4 ± 5.2 versus 55.5 ± 4.0; P < 0.0001). A high correlation was found between SAI and Mini–Mental State Examination (r = −0.68; P < 0.0001).

Conclusions:

These findings add further evidence that differential cholinergic deficiency occurs in PD and PDD. SAI can be a neurophysiological correlate of PDD. © 2012 Movement Disorder Society