Visual Memory Errors in Parkinson's Disease Patient With Visual Hallucinations

Abstract

The occurrences of visual hallucinations seem to be more prevalent in low light and hallucinators tend to be more prone to false positive type errors in memory tasks. Here we investigated whether the richness of stimuli does indeed affect recognition differently in hallucinating and nonhallucinating participants, and if so whether this difference extends to identifying spatial context. We compared 36 Parkinson's disease (PD) patients with visual hallucinations, 32 Parkinson's patients without hallucinations, and 36 age-matched controls, on a visual memory task where color and black and white pictures were presented at different locations. Participants had to recognize the pictures among distracters along with the location of the stimulus. Findings revealed clear differences in performance between the groups. Both PD groups had impaired recognition compared to the controls, but those with hallucinations were significantly more impaired on black and white than on color stimuli. In addition, the group with hallucinations was significantly impaired compared to the other two groups on spatial memory. We suggest that not only do PD patients have poorer recognition of pictorial stimuli than controls, those who present with visual hallucinations appear to be more heavily reliant on bottom up sensory input and impaired on spatial ability.

The psychosis spectrum in Parkinson disease

“…Some studies have reported deficits that are specific to visual — as opposed to verbal — memory 46 . Greater memory deficits have also been found for black-and-white visual stimuli than for coloured visual stimuli, perhaps reflecting more-limited encoding of visually impoverished stimuli in patients with visual hallucinations 47 . A transitive inference test thought to measure hippocampal function has uncovered impairments in patients with PD psychosis 48 .…”

“…Tests purporting to measure visuospatial function, such as the Benton judgement of line orientation and the Rey complex figure test, are often included in test batteries for PD psychosis, but tend not to show significant differences 46,49 (although see Katzen et al 50 for evidence of deficits on the Benton test). The lack of consistent findings could be a test sensitivity issue, as other measures of visuospatial function — for example, the Visual Object and Space Perception (VOSP) number location subtest 47,51 — have been shown to differ between patients with and without visual hallucinations. Tests examining motion, spatiotemporal aspects of visual perception, and eye movements in the PD psychosis spectrum have not been reported to date, but are of particular relevance given the hypothesized role of dysfunctional motion perception and eye movement control in passage and presence hallucinations.…”

Neuroanatomical and cognitive correlates of visual hallucinations in Parkinson’s disease and dementia with Lewy bodies: Voxel-based morphometry and neuropsychological meta-analysis

“…Previous studies suggest that VH in LBD are associated with structural brain abnormalities, evident in brain imaging, mainly in frontal, parietal, and occipitotemporal areas (Pezzoli et al, 2017). Other studies including patients with LBD reported an association between VH and specific cognitive deficits, including visual perception/construction, visual attention, memory, and executive functioning (Barnes and Boubert, 2011;Cagnin et al, 2013;Grossi et al, 2005;Hepp et al, 2013;Koerts et al, 2010;Manganelli et al, 2009). However, findings are often inconsistent and even contradictory, suggesting the need for further research to widen our current knowledge of the neuroanatomical and neuropsychological correlates of this symptom.…”

Multimodal MRI of the hippocampus in Parkinson’s disease with visual hallucinations

“…We compared hippocampal volume, shape, gray matter microstructure, and functional connectivity in individuals with PD with and without visual hallucinations, and healthy controls (HC). We also compared visuospatial memory function in each group because this ability depends upon the hippocampus (Dupret et al 2010 ) and impaired visuospatial function is, in turn, linked to visual hallucinations (Barnes and Boubert 2011 ).…”

“…Visuospatial memory impairment has been reported in those with PD and visual hallucinations (Barnes and Boubert 2011 ), as well individuals with dementia with Lewy bodies (Hamilton et al 2008 , 2011 ). Visuospatial memory relies heavily upon the hippocampus (Dupret et al 2010 ) and is thought to contribute to visual hallucinations (Barnes and Boubert 2011 ). Therefore inter-relationship between hippocampal pathology postulated and this critical cognitive faculty was examined (Robbins et al 1998 ).…”