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Standard Assessments May Miss Psychotic Symptoms in Patients With Parkinson’s Disease

Prompts for delusions and olfactory, tactile, gustatory, and minor hallucinations may identify additional symptoms.


VANCOUVER—Standard clinical assessments of Parkinson’s disease psychosis may miss more than half of psychotic symptoms, according to research presented at the 21st International Congress of Parkinson’s Disease and Movement Disorders. Among 182 patients with Parkinson’s disease, a structured clinical interview with prompts about delusions and olfactory, tactile, gustatory, and minor hallucinations detected more symptoms than standard assessments did.

“There is need for Parkinson’s disease psychosis scales such as our structured clinical interview that have greater sensitivity, particularly for delusions and olfactory, tactile, gustatory, and minor hallucinations,” said Catherine V. Kulick, a researcher at the Marlene and Paolo Fresco Institute for Parkinson’s and Movement Disorders at New York University School of Medicine, and colleagues. “Even isolated minor hallucinations were associated with reduced quality of life and higher prevalence of other nonmotor symptoms.”

As an alternative to standard rating scales for Parkinson’s disease psychosis, which focus on visual and auditory hallucinations and specific delusions, researchers developed a structured clinical interview based on the Parkinson’s disease–specific Scale for Assessment of Positive Symptoms with additional prompts for delusions and olfactory, tactile, gustatory, and minor hallucinations. To evaluate the new tool, the investigators conducted a cross-sectional analysis of 182 consecutive outpatients with Parkinson’s disease (mean age, 67). They evaluated patients with the structured clinical interview as well as a standardized battery of motor, psychiatric, and quality of life scales. Based on the results of the structured clinical interview, investigators classified patients has having major, minor, or no psychotic symptoms.

The structured clinical interview identified 52 patients (28.5%) with psychotic symptoms. Twenty-four patients had major symptoms, and 28 patients had minor symptoms.

A combination of clinical impression, the Unified Parkinson’s Disease Rating Scale (question 2), and the Nonmotor Symptoms Questionnaire (questions 14 and 30) identified 58% of the major psychotic symptoms and 17% of the isolated minor hallucinations that were detected during the structured clinical interview.

About 10% of patients reported major hallucinations, and more patients had major olfactory hallucinations (about 5% of patients) than had major visual, somatic, auditory, and gustatory hallucinations.

Jake Remaly

Suggested Reading

Pagonabarraga J, Martinez-Horta S, Fernández de Bobadilla R, et al. Minor hallucinations occur in drug-naive Parkinson’s disease patients, even from the premotor phase. Mov Disord. 2016;31(1):45-52.

Voss T, Bahr D, Cummings J, et al. Performance of a shortened Scale for Assessment of Positive Symptoms for Parkinson’s disease psychosis. Parkinsonism Relat Disord. 2013;19(3):295-299.

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