Visual hallucinations in dementia with Lewy bodies: transcranial magnetic stimulation study (2011)

Author(s): Taylor JP, Firbank M, Barnett N, Pearce S, Livingstone A, Mosimann U, Eyre JA, McKeith IG, O'Brien JT

    Abstract: Background: The aetiology of visual hallucinations (VH) is poorly understood in dementia with Lewy bodies (DLB). Pathological alterations in visual cortical excitability may be one contributory mechanism. Aims: To determine: 1) visual cortical excitability in DLB patients compared to aged matched controls 2) the relationship between visual cortical excitability and VH in DLB. Methods: Visual cortical excitability was determined by using transcranial magnetic stimulation (TMS) applied to the occiput to elicit phosphenes (transient subjective visual responses) in 21 DLB patients and 19 aged matched controls. Results: Phosphene parameters were similar between control and DLB patients tested. However in DLB patients, TMS measures of visual cortical excitability correlated strongly with the severity of VH (p≤0.005). Six DLBs experienced VH-like phosphenes (e.g. seeing people or figures on stimulation) compared with none of the controls (p=0.02). Conclusions: Increased visual cortical excitability in DLB does not appear to explain VH but it may be a marker for their severity.

      • Date: 20-10-2011
      • Journal: British Journal of Psychiatry
      • Volume: 199
      • Issue: 6
      • Pages: 492-500
      • Publisher: Royal College of Psychiatrists
      • Publication type: Article
      • Bibliographic status: Published

      Professor Janet Eyre
      Professor of Paediatric Neuroscience

      Dr Michael Firbank
      Associate Researcher

      Professor Ian McKeith
      Professor of Old Age Psychiatry

      Professor John O'Brien
      Strategic Research Advisor

      Dr John-Paul Taylor
      Clinical Senior Lecturer/Consultant