Objective: Assess the prevalence of olfactory hallucinations (OlfH) in patients presenting to a tertiary movement disorders outpatient clinic.

Background: Hallucinations can be considered a non-motor feature of alpha synucleinopathies and occur in 20-50% of patients with PD. Due to a lack of awareness as well as paucity of structured questionnaires/tests that target psychosis assessment with an emphasis on OlfH, these are often missed during clinical consultations.

Methods: Single site, IRB-approved ongoing cross sectional study. Patients diagnosed with PD per UK Brain bank criteria were consecutively enrolled with their consent and completed a questionnaire and a self-administered UPSIT smell test. Inability to understand the instructions due to language barrier or severe underlying pathology were exclusion criteria.

Results: 38 male and 18 female subjects were evaluated (n=56). 82% reported no prior olfactory assessment. 19.6% (n=11) patients reported OlfH, 14.2% (n=8) visual, 7.14% auditory and 7.14% tactile hallucinations. 2 patients reported olfactory perseveration but not hallucinations of any modality. Of those with OlfH (see Table-1), mean age was 63.6 years (±10.86). 82% scored poorly on the UPSIT (Severe microsmia – 4, Anosmia – 5). While most reported that OlfH were infrequent, 18% (n=2) had hallucinations lasting greater than one hour and found them unpleasant and upsetting. OlfH related to food were more commonly considered pleasant (n=3).The most commonly described OlfH were “smoke/cigarette-smoke” (54.5%) (Table 2). Other concurrent sensory hallucinations reported included visual (36%), auditory (27%) and tactile (18%).

Conclusions: Non-motor symptoms of PD are often missed in routine clinical practice and have far-reaching implications in patient care. The preliminary data from our center shows that despite hyposmia being a recognized non-motor feature of PD, OlfH tend to be underreported with prevalence ranging from 2.1% to 10% in prior studies compared to 19.6% in our cohort. Our future goals include analyzing the various associations between OlfH and intrinsic variables with our entire cohort (n=200).

References: 1. Papapetropoulos S, Katzen H, Schrag A, et al. A questionnaire-based (UM-PDHQ) study of hallucinations in Parkinson’s disease. BMC Neurology. 2008;8:21. doi:10.1186/1471-2377-8-21. 2. Doty, R. L. (1995). The Smell Identification Test administration manual. Haddon Heights, NJ: Sensonics.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/olfactory-hallucinations-as-a-non-motor-sign-of-parkinsons-disease-a-cross-sectional-study-amongst-patients-in-a-tertiary-movement-center/