Validation of the Psychosis and Hallucinations Questionnaire in Non‐demented Patients with Parkinson's Disease

Abstract

People diagnosed with Parkinson's disease (PD) frequently experience visual and non-visual hallucinations often with comorbid psychosis, however, there is currently no gold standard tool for accurately assessing these symptoms. To address this problem, we designed a novel questionnaire to evaluate the presence of hallucinatory and psychotic symptoms in PD, as well as related symptoms, such as attentional dysfunction and sleep disturbance. We administered the 20-item Psychosis and Hallucinations Questionnaire (PsycH-Q) and three common questionnaire measures in a large cohort of 197 patients with idiopathic PD via a postal survey. We established concurrent validity, convergent validity, and internal consistency of the questionnaire and then assessed test-retest reliability in a subcohort of 44 patients. PsycH-Q was found to be a valid instrument when analogous items were compared across three other existing tools (Spearman's rho range: 0.34-0.64; P < 0.01). PsycH-Q demonstrated a strong relationship between self-reported hallucinations and psychosis and symptoms of the broader hallucinatory phenotype (Kendall's tau = 0.41; P < 0.01; positive predictive value = 0.97). PsycH-Q also displayed a high level of internal consistency (Cronbach's alpha = 0.900; range, 0.696-0.923) and reproducibility (intraclass correlation coefficient = 0.928). PsycH-Q is a simple, valid, self-completed instrument that reliably identifies hallucinations and psychosis in PD and has the ability to characterize related patterns of attentional and sleep impairments. As such, PsycH-Q is a highly valuable tool for use in both clinical and research settings.The evolution of psychotic symptoms is common in Parkinson's disease (PD) and not surprisingly, the presence of visual hallucinations (VH) represents a strong predictor for the development of more florid psychosis, 1 impaired quality of life, 2 and frequently leads to nursing home placement. 3,4 Patients vary in their ability to self-identify these symptoms, making accurate diagnosis and treatment problematic in both the clinical and research setting. 5 Many patients are unable to understand the medical terminology associated with these symptoms, leading to potential under-reporting. Indeed, a recent task force concluded that a novel questionnaire encompassing the broad phenomenology of the disorder would help to increase the sensitivity of the diagnosis of psychosis and VH in PD. 5,6 In addition, hallucinations in PD have consistently been shown to occur in the presence of broader phenotypic abnormalities, including problems with attention, 7-10 general cognition, 8,10 and sleep, 11-13 thus highlighting the specific domains that can be targeted to better characterize the broader phenomenology of psychosis and hallucinations in PD.In an attempt to solve these two related issues, we designed a novel self-report questionnaire-the Psychosis and Hallucinations Questionnaire (PsycH-Q). The questionnaire has been specifically written in "nonscientific" language with a focus on the phen...

Informant‐ and Self‐Appraisals on the Psychosis and Hallucinations Questionnaire (PsycH‐Q) Enhances Detection of Visual Hallucinations in Parkinson's Disease

“…This factor may contribute to an underestimation of the prevalence of symptoms among dyads. However, we are assured by evidence from pilot data (n = 62) collected in the research clinic setting showing that individual patients could complete the questionnaire under 10 minutes without assistance from their caregiver …”

“…However, we are assured by evidence from pilot data (n = 62) collected in the research clinic setting showing that individual patients could complete the questionnaire under 10 minutes without assistance from their caregiver. 11 It is also important to note that the MMSE was the only assessment of cognition used in this study, potentially lacking the sensitivity to detect subtler cognitive deficits. Morecomprehensive cognitive testing would be of value to investigate the agreement of different sources of information about hallucinations in patients with varying degrees of cognitive impairment.…”

“…The PsycH‐Q was developed and comprehensively tested in stages: item generation in consultation with experienced clinicians, a pilot phase to test comprehension and feasibility, followed by a postal survey conducted to test the internal consistency reliability and validity of the questionnaire. Details of the scoring system and administration procedures for PsycH‐Q are provided in our previous publication …”

“…The 20-item PsycH-Q provides scores for the presence of hallucinatory symptoms in five discrete subscales: visual hallucinations, sensory misperceptions, disordered thought, attentional dysfunction, and sleep impairment. 11 These subscales were further split into two sections: items directly evaluating signs of psychosis and hallucinations (Section I: Q 1-13 ), as well as items assessing for related problems with sleep and attention (Section II: Q [14][15][16][17][18][19][20], that capture the broader phenotype known to be associated with development of hallucinations in PD. 11,[16][17][18][19] The PsycH-Q was developed and comprehensively tested in stages: item generation in consultation with experienced clinicians, a pilot phase to test comprehension and feasibility, followed by a postal survey conducted to test the internal consistency reliability and validity of the questionnaire.…”

“…Details of the scoring system and administration procedures for PsycH-Q are provided in our previous publication. 11 In this study, data from the subset of PD patients whose informants consented to participate in the validation process were utilized, in addition to those whose surveys were returned after the conclusion of the validation study. Informants additionally answered the following questions: What is your relationship to the patient?…”