Abstract
BackgroundPatients with Parkinson’s disease (PD) experience visual hallucinations, which may be related to decreased contrast sensitivity (ie, the ability to discern shades of grey).ObjectiveThe objective of this study was to investigate if an online research platform can be used to survey patients with Parkinson’s disease regarding visual hallucinations, and also be used to assess visual contrast perception.MethodsFrom the online patient community, PatientsLikeMe, 964 members were invited via email to participate in this study. Participants completed a modified version of the University of Miami Parkinson’s disease hallucinations questionnaire and an online vision test.ResultsThe study was completed by 27.9% (269/964) of those who were invited: 56.9% of this group had PD (153/269) and 43.1% (116/269) were non-Parkinson’s controls. Hallucinations were reported by 18.3% (28/153) of the Parkinson’s group. Although 10 subjects (9%) in the control group reported experiencing hallucinations, only 2 of them actually described formed hallucinations. Participants with Parkinson’s disease with a mean of 1.75 (SD 0.35) and the control group with a mean of 1.85 (SD 0.36) showed relatively good contrast perception as measured with the online letter test (P=.07). People who reported hallucinations showed contrast sensitivity levels that did not differ from levels shown by people without hallucinations (P=.96), although there was a trend towards lower contrast sensitivity in hallucinators.ConclusionsAlthough more Parkinson's responders reported visual hallucinations, a significant number of non-Parkinson's control group responders also reported visual hallucinations. The online survey method may have failed to distinguish between formed hallucinations, which are typical in Parkinson's disease, and non-formed hallucinations that have less diagnostic specificity. Multiple questions outlining the nature of the hallucinations are required. In a clinical interview, the specific nature of the hallucination would be further refined to rule out a vague description that does not indicate a true, formed visual hallucination. Contrary to previous literature, both groups showed relatively good contrast sensitivity, perhaps representing a ceiling effect or limitations of online testing conditions that are difficult to standardize. Steps can be taken in future trials to further standardize online visual function testing, to refine control group parameters and to take steps to rule out confounding variables such as comorbid disease that could be associated with hallucinations. Contacting subjects via an online health social network is a novel, cost-effective method of conducting vision research that allows large numbers of individuals to be contacted quickly, and refinement of questionnaires and visual function testing may allow more robust findings in future research.
Highlights
Dear PatientsLikeMe member, PatientsLikeMe is collaborating with researchers at Massachussetts Eye & Ear Infirmary to conduct a new research survey
You are being asked to participate in a research study about your experience of visual hallucinations and your ability to see items when they do not have high contrast
The results from the survey will be shared with researchers at the Massachusetts Eye and Ear Infirmary Vision Rehabilitation Clinic
Summary
1. Do you experience any visual hallucinations (seeing things that are not really there or that other people do not see)?. I have never had visual hallucinations (Value: 0) Yes (Value: 1) Not within the past month, but it has happened in the past (Value: 2). Do you experience any other hallucinations (hear, smell, or taste things that are not really there or that other people do not experience)? 5. How severe/emotionally distressing do / did you find these images or visions?. No effect / friendly (Value: 1) Mildly produce little distress (Value: 2) Moderately produce distress and are disturbing and disruptive (Value: 3) Severely very disturbing (medications may be required) (Value: 4)
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