Aberrant gray matter volume and functional connectivity in Parkinson’s disease with minor hallucination

Abstract

Background: Minor hallucination (MH) is the most common psychotic symptom in Parkinson's disease (PD); it can develop into well-structured visual hallucination (VH), suggesting that MH may be a staccato form of wellstructured VH. However, it remains unclear whether the pathogenesis is the same. Therefore, the aim of this study was to investigate the altered gray matter volume (GMV) and functional connectivity (FC) of MH in PD to further understand the complex mechanisms. Materials and methods:We included 67 PD patients who attended the outpatient clinic of Nanjing Medical University Affiliated Brain Hospital and recruited 31 healthy controls (HC). Demographic data and clinical characteristics of all subjects were recorded, and cranial structural magnetic resonance imaging (MRI) and resting-state functional MRI data were acquired. Patients were classified into the PD with MH (PD-MH) group and PD without hallucinations or delusions (PD-NH) group. Voxel-based morphometry was used to analyze the differences in GMV in the structural pattern. Seed-based FC was used to analyze the functional pattern. Gaussian random field correction was used, with voxel level P < 0.001 and cluster level P < 0.05 representing statistically significant differences. Finally, the correlation between FC values and scores on the clinical characteristics assessment scale was analyzed.Results: In the GMV analysis, compared to the PD-NH group, the PD-MH group had reduced GMV in the medial superior frontal gyrus (SFGmed). In the FC analysis, the FC between the SFGmed and the left middle occipital gyrus and right calcarine sulcus decreased in the PD-MH group compared with the PD-NH group, while the FC between SFGmed and the left middle temporal gyrus increased. Correlation analysis revealed that the FC values of the SFGmed and right calcarine sulcus were correlated with the assessment Frontiers in Aging Neuroscience 01 frontiersin.org Zhong et al. 10.3389/fnagi.2022.923560 scores for anxiety and sleep symptoms. The FC values of the SFGmed and left middle occipital gyrus were correlated with assessment scores for rapid eye movement disorder. Conclusion:The aberrant structure and function of the default mode network and visual processing areas seems to facilitate the generation of MH in PD, as the alteration was previously found in well-structured VH, suggesting that the two hallucinations have similar pathophysiological mechanisms.

Genetic mechanisms underlying gray matter atrophy in Parkinson’s disease: a combined transcriptome and neuroimaging study

“…Some disparities could be attributed to the limited number of our patient samples. The overlap results emphasize the signi cant appearance of gray matter reduction in the superior temporal gyrus, coherent with previous research ndings 5,[27][28][29] . Abnormalities in this region have been linked with key symptoms of PD, including theory of mind impairment, apathy, cognitive impairment, depression, freezing of the gait, and frequent falls [30][31][32][33] .…”

Illusory Responses across the Lewy Body Disease Spectrum

“…The remaining associations with illusory responses are consistent with previous findings, including processing speed, language (both visually based naming and fluency), and visual memory 49 . Our results lend additional support to the hypotheses that visual hallucinations (even minor illusory phenomena) may occur due to some combination of visual information processing, attention deficits or disruptions to attention networks, and/or disruptions in the default mode network 50–54 . To date, there is a lack of clear understanding of the timing and relative importance of these changes, as well how deficits in language may fit with current models.…”

“…49 Our results lend additional support to the hypotheses that visual hallucinations (even minor illusory phenomena) may occur due to some combination of visual information processing, attention deficits or disruptions to attention networks, and/or disruptions in the default mode network. [50][51][52][53][54] To date, there is a lack of clear understanding of the timing and relative importance of these changes, as well how deficits in language may fit with current models. Given this, and that our results are in a relatively small sample and do not hold up to multiple comparisons testing, further exploration into domain-specific relationships between pareidolias and cognitive performance is needed to provide insight into common underlying pathways between psychosis and specific cognitive domains.…”

Minor hallucinations in Parkinson’s disease with probable rapid eye movement sleep behavior disorder

“…Although only a few articles have been published on imaging studies of MHs, several similar structural and functional characteristics between MHs and VHs have been found. Apart from gray matter atrophy in limbic and paralimbic regions in patients with VHs ( Lenka et al, 2015 ), morphometric studies also reported reduced gray matter volume of posterior cingulate cortex and parahippocampal gyri in patients with MHs ( Bejr-Kasem et al, 2019 ; Zhong et al, 2022 ). Considering that RBD represents a more aggressive PD subtype ( Fereshtehnejad et al, 2015 ), we conjecture that MHs in this population may be associated with damage to related brain regions in the early stage.…”