Pareidolias and cognition in isolated REM sleep behavior disorder

Clinical correlates of pareidolias and color discrimination deficits in idiopathic REM sleep behavior disorder and Parkinson's disease

Visuoperceptual dysfunction is common in Parkinson's disease (PD) and is also reported in its prodromal phase, isolated REM sleep behavior disorder (iRBD). We aimed to investigate color discrimination ability and complex visual illusions known as pareidolias in patients with iRBD and PD compared to healthy controls, and their associating clinical factors. 46 iRBD, 43 PD, and 64 healthy controls performed the Farnsworth-Munsell 100 hue test and noise pareidolia tests. Any relationship between those two visual functions and associations with prodromal motor and non-motor manifestations were evaluated, including MDS-UPDRS part I to III, Cross-Cultural Smell Identification Test, sleep questionnaires, and comprehensive neuropsychological assessment. iRBD and PD patients both performed worse on the Farnsworth-Munsell 100 hue test and had greater number of pareidolias compared to healthy controls. No correlations were found between the extent of impaired color discrimination and pareidolia scores in either group. In iRBD patients, pareidolias were associated with frontal executive dysfunction, while impaired color discrimination was associated with visuospatial dysfunction, hyposmia, and higher MDS-UPDRS-III scores. Pareidolias in PD patients correlated with worse global cognition, whereas color discrimination deficits were associated with frontal executive dysfunction. Color discrimination deficits and pareidolias are frequent but does not correlate with each other from prodromal to clinically established stage of PD. The different pattern of clinical associates with the two visual symptoms suggests that evaluation of both color and pareidolias may aid in revealing the course of neurodegeneration in iRBD and PD patients.

Cognitive and motor profiles as prodromal markers in predicting phenoconversion and phenotype in isolated REM sleep behavior disorder

OBJECTIVE

To determine the clinical markers based on cognitive and motor profiles in predicting phenoconverion and phenotype in isolated rapid eye movement sleep behavior disorder (iRBD).

METHODS

45 iRBD patients and 25 healthy controls were included in the follow-up study. All participates received comprehensive evaluations of cognitive, motor and autonomic function at baseline. Positive phenoconversion were identified according to standard diagnostic criteria during follow-up.

RESULTS

21 iRBD patients displayed phenoconversion in a mean follow-up of 2.9 ± 1.6 years, with 14 presenting motor phenotype and 7 cognitive phenotype. In iRBD, visuospatial, memory, attention-executive function, information processing speed, and motor function predicted phenoconversion, with the combination of Trail Making Test (TMT) and Alternate-tap Test (ATT) performing best (sensitivity = 95.0 %, specificity = 75.0 %); attention-executive function, information processing speed, and motor function predicted motor phenotype conversion, with the combination of TMT and ATT performing best (sensitivity = 100 %, specificity = 66.7 %); visuospatial, memory, and attention-executive function predicted cognitive phenotype conversion, with TMT performing best (sensitivity = 83.3 %, specificity = 91.7 %). Furthermore, individuals with lower z-scores of TMT, Symbol Digit Modalities Test, and ATT than the established cutoff values in iRBD exhibited a significantly higher risk for phenoconversion at follow-up (HR = 2.98, 9.53, 11.68; respectively).

CONCLUSIONS

In iRBD, the attention-executive and motor function served as optimum combined markers in predicting phenoconversion and motor phenotype, whereas the attention-executive function performed best in predicting cognitive phenotype. Poor attention-executive function, information processing speed and motor function in iRBD independently increased the risk of phenoconversion.

Longitudinal evolution of cortical thickness signature reflecting Lewy body dementia in isolated REM sleep behavior disorder: a prospective cohort study

BACKGROUND

The isolated rapid-eye-movement sleep behavior disorder (iRBD) is a prodromal condition of Lewy body disease including Parkinson's disease and dementia with Lewy bodies (DLB). We aim to investigate the longitudinal evolution of DLB-related cortical thickness signature in a prospective iRBD cohort and evaluate the possible predictive value of the cortical signature index in predicting dementia-first phenoconversion in individuals with iRBD.

METHODS

We enrolled 22 DLB patients, 44 healthy controls, and 50 video polysomnography-proven iRBD patients. Participants underwent 3-T magnetic resonance imaging (MRI) and clinical/neuropsychological evaluations. We characterized DLB-related whole-brain cortical thickness spatial covariance pattern (DLB-pattern) using scaled subprofile model of principal components analysis that best differentiated DLB patients from age-matched controls. We analyzed clinical and neuropsychological correlates of the DLB-pattern expression scores and the mean values of the whole-brain cortical thickness in DLB and iRBD patients. With repeated MRI data during the follow-up in our prospective iRBD cohort, we investigated the longitudinal evolution of the cortical thickness signature toward Lewy body dementia. Finally, we analyzed the potential predictive value of cortical thickness signature as a biomarker of phenoconversion in iRBD cohort.

RESULTS

The DLB-pattern was characterized by thinning of the temporal, orbitofrontal, and insular cortices and relative preservation of the precentral and inferior parietal cortices. The DLB-pattern expression scores correlated with attentional and frontal executive dysfunction (Trail Making Test-A and B: R = - 0.55, P = 0.024 and R = - 0.56, P = 0.036, respectively) as well as visuospatial impairment (Rey-figure copy test: R = - 0.54, P = 0.0047). The longitudinal trajectory of DLB-pattern revealed an increasing pattern above the cut-off in the dementia-first phenoconverters (Pearson's correlation, R = 0.74, P = 6.8 × 10^-4) but no significant change in parkinsonism-first phenoconverters (R = 0.0063, P = 0.98). The mean value of the whole-brain cortical thickness predicted phenoconversion in iRBD patients with hazard ratio of 9.33 [1.16-74.12]. The increase in DLB-pattern expression score discriminated dementia-first from parkinsonism-first phenoconversions with 88.2% accuracy.

CONCLUSION

Cortical thickness signature can effectively reflect the longitudinal evolution of Lewy body dementia in the iRBD population. Replication studies would further validate the utility of this imaging marker in iRBD.

Illusory Responses across the Lewy Body Disease Spectrum

OBJECTIVE

This study was undertaken to study pareidolias, or perceived meaningful objects in a meaningless stimulus, in patients across the Lewy body (LB) disease spectrum, where most do not report hallucinations or delusions.

METHODS

We studied illusory responses on the Noise Pareidolia Task in 300 participants (38 cognitively impaired LB, 65 cognitively unimpaired LB, 51 Alzheimer disease spectrum [AD-s], 146 controls). Pairwise between-group comparisons examined how diagnosis impacts the number of illusory responses. Ordinal regression analysis compared the number of illusory responses across diagnosis groups, adjusting for age, sex, and education. Analyses were repeated after removing participants with reported hallucinations or delusions.

RESULTS

Cognitively impaired LB participants were 12.3, 4.9, and 4.6 times more likely than control, cognitively unimpaired LB, and AD-s participants, respectively, to endorse illusory responses. After adjusting for age, sex, and education, the probability of endorsing 1 or more illusory responses was 61% in the cognitively impaired LB group, compared to 26% in AD-s, 25% in cognitively unimpaired LB, and 12% in control participants. All results were similar after repeated analysis only in participants without hallucinations or delusions. In LB without hallucinations or delusions, 52% with mild cognitive impairment and 66.7% with dementia endorsed at least 1 illusory response.

INTERPRETATION

We found illusory responses are common in cognitively impaired LB patients, including those without any reported psychosis. Our data suggest that, prior to the onset of hallucinations and delusions, the Noise Pareidolia Task can easily be used to screen for unobtrusive pareidolias in all LB patients. ANN NEUROL 2023;93:702-714.

Utility of the 20-Item Noise Pareidolia Task (NPT-20) for Assessing Visuoperceptual Disturbances Associated with Complex Visual Hallucinations in Parkinson's Disease

Background

Complex visual hallucinations (VH) are a common complication of Parkinson's disease (PD). Recent studies have demonstrated relevance of face pareidolia to VH in PD and Lewy body dementia (LBD).

Objective

This study examined utility of the 20-item Noise Pareidolia Task (NPT-20) in assessing visuoperceptual disturbances associated with VH in PD.

Methods

Retrospective chart review included 46 consecutive PD patients who completed NPT-20 during clinical neuropsychological evaluation.

Results

About half the sample (43%) reported VH. PD with VH made significantly more false-positive pareidolia errors on the NPT-20 (p < 0.0001). A cut-off of 2 errors yielded 40% sensitivity, 100% specificity to VH; cut-off of 1 yielded 75% sensitivity, 81% specificity. NPT-20 was not associated with any other clinical or demographic factor. Across groups, NPT-20 evinced moderate correlations with visuospatial functioning and visual memory.

Conclusions

Current findings support utility of the NPT-20 for evaluating visuoperceptual disturbances associated with VH in PD.

[Auditory phenomena as differential diagnostics to tinnitus]

INTRODUCTION

In the auditory system, subjective tinnitus is known as phantom perception. Humans also report illusionary misperceptions of real listening impressions and complex scene-like acoustic fantasies without external hearing stimulus. The exact pathophysiological relationships of the auditory phenomena are still unclear. Important comorbidities include hearing loss, brain disease and mental disorders.

METHODS

In a literature search in the PubMed database, publications were evaluated until March 2021 on the search terms tinnitus, palinacousis, pareidolia, synesthesia, aura, acoustic hallucination with regard to similarities and differences to subjective tinnitus.

RESULTS

Subjective tinnitus can occur together with other auditory phenomena in an individual. Diagnostically important is the relationship between hearing loss and tinnitus as well as between tinnitus and hearing loss in the corresponding frequency range. With hearing loss, other auditory phenomena may occur.

CONCLUSION

The occurrence of various auditory phenomena simultaneously in a person suggests an auditory perceptual continuum with common physiological processing structures. People with hearing loss should be asked about the various auditory phenomena. For all auditory phenomena, audiometric examination should be part of the diagnostic standard.

Biomarkers of conversion to α-synucleinopathy in isolated rapid-eye-movement sleep behaviour disorder

Patients with isolated rapid-eye-movement sleep behaviour disorder (RBD) are commonly regarded as being in the early stages of a progressive neurodegenerative disease involving α-synuclein pathology, such as Parkinson's disease, dementia with Lewy bodies, or multiple system atrophy. Abnormal α-synuclein deposition occurs early in the neurodegenerative process across the central and peripheral nervous systems and might precede the appearance of motor symptoms and cognitive decline by several decades. These findings provide the rationale to develop reliable biomarkers that can better predict conversion to clinically manifest α-synucleinopathies. In addition, biomarkers of disease progression will be essential to monitor treatment response once disease-modifying therapies become available, and biomarkers of disease subtype will be essential to enable prediction of which subtype of α-synucleinopathy patients with isolated RBD might develop.

Serum metabolic biomarkers for synucleinopathy conversion in isolated REM sleep behavior disorder

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is a prodromal stage of Lewy-type synucleinopathies (LTS), which can present either with an initial predominant parkinsonism (Parkinson’s disease (PD)) or dementia (dementia with Lewy bodies (DLB)). To provide insights into the underlying pathogenic mechanisms, the lipoprotein and protein glycosylation profile of 82 iRBD patients, collected before and/or after their conversion to an overt LTS, and 29 matched control serum samples were assessed by nuclear magnetic resonance (NMR) spectroscopy. Data were statistically analyzed to identify altered metabolites and construct predictive models. Univariant analysis detected no differences between iRBD patients with an LTS compared to controls. However, significant differences were found when the analysis distinguished between iRBD patients that manifested initially predominant parkinsonism (pre-PD) or dementia (pre-DLB). Significant differences were also found in the analysis of paired iRBD samples pre- and post-LTS diagnosis. Predictive models were built and distinguished between controls and pre-DLB patients, and between pre-DLB and pre-PD patients. This allowed a prediction of the possible future clinical outcome of iRBD patients. We provide evidence of altered lipoprotein and glycosylation profiles in subgroups of iRBD patients. Our results indicate that metabolic alterations and inflammation are involved in iRBD pathophysiology, and suggest biological differences underlying the progression of LTS in iRBD patients. Our data also indicate that profiling of serum samples by NMR may be a useful tool for identifying short-term high-risk iRBD patients for conversion to parkinsonism or dementia.

Evaluating a novel behavioral paradigm for visual hallucinations in Dementia with Lewy bodies

The aim of this study was to evaluate the utility of the Bistable Percept Paradigm (BPP), a computerised behavioural task that has previously been utilised for the assessment of visual hallucinations in Parkinson's Disease, in a Dementia with Lewy bodies (DLB) cohort. Dementia with Lewy bodies patients demonstrated poorer performance than healthy controls (HC) on the BPP with significantly more misperceptions and a greater failure to detect bistable percepts correctly compared to HC. Further, the number of misperceptions was also correlated with the severity of hallucinations. The findings from this study demonstrate that the BPP is a viable tool to measure misperceptions in DLB patients.