Patient and Informant Views on Visual Hallucinations in Parkinson Disease

Behavioral and neural correlates of pareidolic illusions in dementia with Lewy bodies

INTRODUCTION

Pareidolia, a form of visual illusions phenomenologically similar to complex visual hallucinations, is a phenomenon that is associated with visual hallucinations in dementia with Lewy bodies (DLB). This study aimed to identify commonalities and differences in behavioral and neural correlates between pareidolic illusions and visual hallucinations in DLB.

METHODS

Forty-three patients with DLB underwent the scene pareidolia test, which evokes and measures pareidolic illusions, and standardized neuropsychological and behavioral assessments. Regional cerebral blood flow (rCBF) was measured by single-photon emission computed tomography. Factor analysis was performed to assess the relationships among pareidolic illusions, cognitive functions, and behavioral symptoms. Partial least squares correlation analysis was used to investigate the relationship between these symptoms and rCBF.

RESULTS

Factor analysis yielded three behavior factors: the first factor (hallucinations/fluctuations) consisted of pareidolic illusions, visual hallucinations, and fluctuating cognition; the second factor (general cognitive function) consisted of general cognitive function and working memory; and the third factor (visual processing) consisted of visual processing and pareidolic illusions. Partial least squares correlation analysis identified two brain-behavior correlation patterns: (1) rCBF reduction in the frontal and perisylvian/periventricular regions was associated with lower general cognitive function and lower visual processing; and (2) rCBF reduction in the bilateral occipitotemporal cortex was associated with more severe hallucinations/fluctuations and lower visual processing.

CONCLUSIONS

At the behavioral level, pareidolic illusions are associated with visual hallucinations, fluctuating cognition, and visual processing in DLB. At the neural level, pareidolic illusions may arise from the synergistic effects of global neuropathological changes and occipitotemporal cortical dysfunctions.

Exploring Bottom-Up Visual Processing and Visual Hallucinations in Parkinson's Disease With Dementia

Visual hallucinations (VH) are a common symptom of Parkinson's disease with dementia (PDD), affecting up to 65% of cases. Integrative models of their etiology posit that a decline in executive control of the visuo-perceptual system is a primary mechanism of VH generation. The role of bottom-up processing in the manifestation of VH in this condition is still not clear although visual evoked potential (VEP) differences have been associated with VH at an earlier stage of PD. Here we compared the amplitude and latency pattern reversal VEPs in healthy controls (n = 21) and PDD patients (n = 34) with a range of VH severities. PDD patients showed increased N2 latency relative to controls, but no significant differences in VEP measures were found for patients reporting complex VH (CVH) (n = 17) compared to those without VH. Our VEP findings support previous reports of declining visual system physiology in PDD and some evidence of visual system differences between patients with and without VH. However, we did not replicate previous findings of a major relationship s between the integrity of the visual pathway and VH.

Visual hallucinations in dementia and Parkinson's disease: A qualitative exploration of patient and caregiver experiences

OBJECTIVES

Visual hallucinations (VHs) can occur in several clinical conditions, of which the dementias, broadly defined, and Parkinson's disease rank among the most common. There is limited research on the lived experience of hallucinations among affected individuals and therefore a lack of evidence-based management strategies. This study used qualitative methods to explore the VH experience of individuals with dementia or Parkinson's disease and their informal caregivers.

METHODS

In-depth interviews were conducted with 10 individuals with VHs and dementia and 11 informal caregivers, and 11 individuals with VHs and Parkinson's disease and 9 informal caregivers. Interviews were analysed using an inductive thematic approach.

RESULTS

Three themes emerged from the data: "Insight and distress," "Caregiver approach: challenging v reassurance," and "Normality and stigma." Insight appeared to affect whether hallucinations were perceived as threatening and whether acceptance occurred over time. Emotional reactions and management strategies varied as insight changed with disease progression. Concerns around stigmatisation negatively influenced help-seeking and acceptance of the hallucinations.

CONCLUSIONS

Degree of insight and cognitive ability appear fundamental to the lived experience of hallucinations. Irrespective of the clinical context, support in early stages should focus on raising awareness of VH, symptom disclosure, stigma reduction, and contact with others affected. In later stages, the focus shifts to informal caregiver needs and a flexible approach to reassuring those affected.

Psychometric Properties and Characteristics of the North-East Visual Hallucinations Interview in Parkinson's Disease

BACKGROUND

Visual Hallucinations (VH) are a common symptom experienced by individuals with Parkinson's disease (PD); however, a validated measure of VH has yet to be established for this population. The North-East Visual Hallucinations Interview (NEVHI), a promising VH measure, has not been well validated in PD. The aim of this study was to evaluate the convergent and discriminant validity of the NEVHI as well as the proportional identification and characteristics of VH in PD.

METHODS

One hundred seventeen individuals with PD completed the NEVHI as well as evaluations of psychological, cognitive, motor, and visual functioning as measures of convergent and divergent validity. The hallucination items from the Neuropsychiatric Inventory (NPI) and the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Scale (MDS-UPDRS) were used to assess convergent validity.

RESULTS

The NEVHI identified 20.5% of PD patients with VH, which consisted of all individuals detected by the MDS-UPDRS and NPI and nine additional individuals not detected by the other measures. The NEVHI was strongly correlated with the MDS-UPDRS hallucinations item, and weakly correlated with the NPI VH item. Weak to non-significant correlations were found between the NEVHI and measures of psychological, cognitive, motor, visual, and demographic characteristics.

DISCUSSION

The NEVHI identified a greater number of individuals with VH than either the MDS-UPDRS or NPI. Results demonstrated good convergent validity between the NEVHI and a clinician-administered-to-patient-report measure of VH and excellent divergent validity, supporting the NEVHI as a valid and preferable measure for assessing the presence of VH in PD.

Visual Hallucinations in Eye Disease and Lewy Body Disease

OBJECTIVES

Visual hallucinations (VH) most commonly occur in eye disease (ED), Parkinson disease (PD), and Lewy body dementia (LBD). The phenomenology of VH is likely to carry important information about the brain areas within the visual system generating them.

METHODS

Data from five controlled cross-sectional VH studies (164 controls, 135 ED, 156 PD, 79 [PDD 48 + DLB 31] LBD) were combined and analyzed. The prevalence, phenomenology, frequency, duration, and contents of VH were compared across diseases and sex.

RESULTS

Simple VH were most common in ED patients (ED 65% versus LBD 22% versus PD 9%, χ(2) = 31.43, df = 2, p < 0.001), whereas complex VH were more common in LBD (LBD 76% versus ED 38%, versus PD 28%, χ(2) = 96.80, df = 2, p < 0.001). The phenomenology of complex VH was different across diseases and sex. ED patients reported more "flowers" (ED 21% versus LBD 6% versus PD 0%, χ(2) = 10.04, df = 2, p = 0.005) and "body parts" (ED 40% versus LBD 17% versus PD 13%, χ(2) = 11.14, df = 2, p = 0.004); in contrast, LBD patients reported "people" (LBD 85% versus ED 67% versus PD 63%, χ(2) = 6.20, df = 2, p = 0.045) and "animals/insects" (LBD 50% versus PD 42% versus ED 21%, χ(2) = 9.76, df = 2, p = 0.008). Men reported more "machines" (13% versus 2%, χ(2) = 6.94, df = 1, p = 0.008), whereas women reported more "family members/children" (48% versus 29%, χ(2) = 5.10, df = 1, p = 0.024).

CONCLUSIONS

The phenomenology of VH is likely related to disease-specific dysfunctions within the visual system and to past, personal experiences.