Hallucinations and REM sleep behaviour disorder in Parkinson's disease: Dream imagery intrusions and other hypotheses

Raffaele Manni, Michele Terzaghi, Pietro Luca Ratti, Alessandra Repetto, Roberta Zangaglia, Claudio Pacchetti

Research output: Contribution to journalArticlepeer-review


REM sleep behaviour disorder (RBD) is a REM sleep-related parasomnia which may be considered a " dissociated state of wakefulness and sleep" , given that conflicting elements of REM sleep (dreaming) and of wakefulness (sustained muscle tone and movements) coexist during the episodes, leading to motor and behavioural manifestations reminiscent of an enacted dream. RBD has been reported in association with α-synucleinopathies: around a third of patients with Parkinson's disease (PD) have full-blown RBD.Recent data indicate that PD patients with RBD are more prone to hallucinations than PD patients without this parasomnia. However it is still not clear why RBD in PD is associated with an increased prevalence of VHs.Data exist which suggest that visual hallucinations in PD may be the result of untimely intrusions of REM visual imagery into wakefulness. RBD, which is characterised by a REM sleep dissociation pattern, might be a condition that particularly favours such intrusions. However, other hypotheses may be advanced. In fact, deficits in attentional, executive, visuoperceptual and visuospatial abilities have been documented in RBD and found to occur far more frequently in PD with RBD than in PD without RBD. Neuropsychological deficits involving visual perception and attentional processes are thought to play an important role in the pathophysiology of VHs. On this basis, RBD in PD could be viewed as a contributory risk factor for VHs.

Original languageEnglish
Pages (from-to)1021-1026
Number of pages6
JournalConsciousness and Cognition
Issue number4
Publication statusPublished - Dec 2011


  • Hallucinations
  • Parkinson's disease
  • REM sleep behaviour disorder

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Arts and Humanities (miscellaneous)
  • Developmental and Educational Psychology


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