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Hallucinations in Parkinson disease
Diederich NJ, Fénelon G, Stebbins G, Goetz CG.. Nature reviews. Neurology, 2009-06-01
Topic: Risk, prevention and care in population studies
Patients with Parkinson disease (PD) can experience hallucinations (spontaneous aberrant perceptions) and illusions (misinterpretations of real perceptual stimuli). Of such phenomena, visual hallucinations (VHs) and illusions are the most frequently encountered, although auditory, olfactory and tactile hallucinations can also occur. In cross-sectional studies, VHs occur in approximately one-third of patients, but up to three-quarters of patients might develop VHs during a 20-year period. Hallucinations can have substantial psychosocial effects and, historically, were the main reason for placing patients in nursing homes. Concomitant or overlapping mechanisms are probably active during VHs, and these include the following: central dopaminergic overactivity and an imbalance with cholinergic neurotransmission; dysfunction of the visual pathways, including specific PD-associated retinopathy and functional alterations of the extrastriate visual pathways; alterations of brainstem sleep-wake and dream regulation; and impaired attentional focus. Possible treatments include patient-initiated coping strategies, a reduction of antiparkinson medications, atypical neuroleptics and, potentially, cholinesterase inhibitors. Evidence-based studies, however, only support the use of one atypical neuroleptic, clozapine, and only in patients without dementia. Better phenomenological discrimination, combined with neuroimaging tools, should refine therapeutic options and improve prognosis. The aim of this Review is to present epidemiological, phenomenological, pathophysiological and therapeutic aspects of hallucinations in PD.
Key findings
- Concomitant or overlapping mechanisms are probably active during VHs, and these include the following: central dopaminergic overactivity and an imbalance with cholinergic neurotransmission; dysfunction of the visual pathways, including specific PD-associated retinopathy and functional alterations of the extrastriate visual pathways; alterations of brainstem sleep-wake and dream regulation; and impaired attentional focus.
- Possible treatments include patient-initiated coping strategies, a reduction of antiparkinson medications, atypical neuroleptics and, potentially, cholinesterase inhibitors.
- Evidence-based studies, however, only support the use of one atypical neuroleptic, clozapine, and only in patients without dementia.
- Better phenomenological discrimination, combined with neuroimaging tools, should refine therapeutic options and improve prognosis.
- The aim of this Review is to present epidemiological, phenomenological, pathophysiological and therapeutic aspects of hallucinations in PD.
Why it matters
This review describes hallucinations in Parkinson disease and their possible mechanisms, and notes that evidence-based studies support only one atypical neuroleptic, clozapine, and only in patients without dementia. It reports no treatment, cure or prevention for Alzheimer's disease.
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Study details
- Study designcross-sectional
- Evidence strengthLow
How this study scored 49/100
Published in a peer-reviewed journal, and it is a snapshot of people at one point in time. Scored zero for sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Nature reviews. Neurology) |
| Journal's citation record | 3 / 4 | Nature Reviews Neurology: journal h-index 269 (OpenAlex, 2026-10-29) |
| Study design | 4 / 12 | A snapshot of people at one point in time |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2009 — within 20 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 6 / 7 | Cited 317 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 16.7 citations a year over 19 year(s) since 2009 |
| Impact for its field and year | 2 / 6 | Cited 1.2× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 3 other studies in this library |
| Still being cited | 2 / 4 | Cited 41 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Christopher G. Goetz: h-index 117 (OpenAlex, whole career) |
| Institution's track record | 0 / 3 | Rush University Medical Center: institution h-index 670 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 4 institution(s) in 3 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 19498436) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 49 / 100 | — |
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Diederich, N. J., Fénelon, G., Stebbins, G., & Goetz, C. G. (2009). Hallucinations in Parkinson disease. Nature reviews. Neurology. https://doi.org/10.1038/nrneurol.2009.62
Vancouver
Diederich NJ, Fénelon G, Stebbins G, Goetz CG. Hallucinations in Parkinson disease. Nature reviews. Neurology. 2009. doi:10.1038/nrneurol.2009.62. PMID: 19498436.
BibTeX
@article{diederich2009-19498436,
author = {Diederich, N. J. and Fénelon, G. and Stebbins, G. and Goetz, C. G.},
title = {{Hallucinations in Parkinson disease}},
journal = {Nature reviews. Neurology},
year = {2009},
doi = {10.1038/nrneurol.2009.62},
pmid = {19498436},
url = {https://doi.org/10.1038/nrneurol.2009.62}
}
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