Functional involvement of central cholinergic circuits and visual hallucinations in Parkinsons disease

Fiore Manganelli, Carmine Vitale, Gabriella Santangelo, Chiara Pisciotta, Rosa Iodice, Autilia Cozzolino, Raffaele Dubbioso, Marina Picillo, Paolo Barone, Lucio Santoro

Research output: Contribution to journalArticlepeer-review

Abstract

Visual hallucinations (VHs) represent a frequent and disturbing complication of Parkinsons disease. Evidence suggests that VH can be related to central cholinergic dysfunction. Short-latency afferent inhibition (SAI) technique gives the opportunity to test an inhibitory cholinergic circuit in the human cerebral motor cortex. This inhibition of motor-evoked potentials can be observed when transcranial magnetic stimulation is delivered with a delay ranging from 2 to 8 ms, after a peripheral nerve afferent input has reached the somatosensory cortex. We applied SAI technique in 10 non-demented patients with Parkinsons disease with VHs, in 12 non-demented patients with Parkinsons disease without VHs (NVH-pts) and in 11 age-matched normal controls. All patients with Parkinsons disease underwent a battery of neuropsychological tests to assess frontal and visuospatial functions, memory and attention. SAI was significantly reduced in patients with VHs compared with controls and patients without VHs. Neuropsychological examination showed a mild cognitive impairment in 16 out of 22 patients with Parkinsons disease. In addition, we found that in our patients with VHs, performance of some tasks evaluating visuospatial functions and attentional/frontal lobe functions was significantly more impaired than in patients without VHs. SAI abnormalities, presence of VH and neuropsychological results strongly support the hypothesis of cholinergic dysfunction in some patients with Parkinsons disease, who will probably develop a dementia. A follow-up study of our patients is required to verify whether SAI abnormalities can predict a future severe cognitive decline. Moreover, SAI can also be very useful to follow-up the efficacy of anti-cholinesterase therapies.

Original languageEnglish
Pages (from-to)2350-2355
Number of pages6
JournalBrain
Volume132
Issue number9
DOIs
Publication statusPublished - Sep 2009

Keywords

  • Cognitive deficits
  • Parkinsons disease
  • Short-latency afferent inhibition
  • TMS
  • Visual hallucinations

ASJC Scopus subject areas

  • Clinical Neurology

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