Pathology and temporal onset of visual hallucinations, misperceptions and family misidentification distinguishes dementia with Lewy bodies from Alzheimer's disease

Casting shadows of perception: An exploration of visual hallucinations

ABSTRACT

Hallucinations can be caused by biological, psychological, neurological, ophthalmological, and environmental factors. This article discusses a selection of the various conditions that can present with visual disturbances and hallucinations including schizophrenia, HIV, neurosyphilis, hyperammonemia, migraine, substance use, brain tumors, sleep disturbances, thyroid disorders, delirium, ophthalmologic conditions, and Lewy body dementia, providing an overview of the differential diagnosis of visual hallucinations. The mechanisms by which these conditions can lead to hallucinations are also discussed, and insight into the recommended medical workup for each is provided.

Neuropathological correlates of neuropsychiatric symptoms in dementia

INTRODUCTION

Neuropsychiatric symptoms (NPS) are common in Lewy body disease (LBD), but their etiology is poorly understood.

METHODS

In a population-based post mortem study neuropathological data was collected for Lewy body (LB) neuropathology, neurofibrillary tangles (NFT), amyloid beta burden, TDP-43, lacunar infarcts, cerebral amyloid angiopathy (CAA), and hyaline atherosclerosis. Post mortem interviews collected systematic information regarding NPS and cognitive status. A total of 1038 cases were included: no pathology (NP; n = 761), Alzheimer's disease (AD; n = 189), LBD (n = 60), and AD+LBD (n = 28).

RESULTS

Hallucinations were associated with higher LB Braak stages, while higher NFT Braak staging was associated with depression, agitation, and greater number of symptoms in the Neuropsychiatric Inventory. Cases with dual AD+LBD pathology had the highest risk of hallucinations, agitation, apathy, and total symptoms but a multiplicative interaction between these pathologies was not significant.

DISCUSSION

LB and AD pathology contribute differentially to NPS likely with an additive process contributing to the increased burden of NPS.

Diencephalic versus Hippocampal Amnesia in Alzheimer's Disease: The Possible Confabulation-Misidentification Phenotype

BACKGROUND

Alzheimer's disease (AD) is clinically heterogeneous, including the classical-amnesic (CA-) phenotype and some variants.

OBJECTIVE

We aim to describe a further presentation we (re)named confabulation-misidentification (CM-) phenotype.

METHODS

We performed a retrospective longitudinal case-series study of 17 AD outpatients with the possible CM-phenotype (CM-ADs). Then, in a cross-sectional study, we compared the CM-ADs to a sample of 30 AD patients with the CA-phenotype (CA-ADs). The primary outcome was the frequency of cognitive and behavioral features. Data were analyzed as differences in percentage by non-parametric Chi Square and mean differences by parametric T-test.

RESULTS

Anterograde amnesia (100%) with early confabulation (88.2%), disorientation (88.2%) and non-infrequently retrograde amnesia (64.7%) associated with reduced insight (88.2%), moderate prefrontal executive impairment (94.1%) and attention deficits (82.3%) dominated the CM-phenotype. Neuropsychiatric features with striking misidentification (52.9%), other less-structured delusions (70.6%), and brief hallucinations (64.7%) were present. Marked behavioral disturbances were present early in some patients and very common at later stages. At the baseline, the CM-ADs showed more confabulation (p < 0.001), temporal disorientation (p < 0.02), misidentification (p = 0.013), other delusions (p = 0.002), and logorrhea (p = 0.004) than the CA-ADs. In addition, more social disinhibition (p = 0.018), reduction of insight (p = 0.029), and hallucination (p = 0.03) persisted at 12 months from baseline. Both the CA- and CM-ADs showed anterior and medial temporal atrophy. Compared to HCs, the CM-ADs showed more right fronto-insular atrophy, while the CA-ADs showed more dorsal parietal, precuneus, and right parietal atrophy.

CONCLUSION

We described an AD phenotype resembling diencephalic rather than hippocampal amnesia and overlapping the past-century description of presbyophrenia.

Cortical complexity alterations in the medial temporal lobe are associated with Alzheimer's disease psychosis

Psychosis is frequent in Alzheimer's disease (AD) and it is associated with a worse disease course. AD psychosis may represent a distinct AD phenotype, though its specific neurobiological underpinnings have yet to be identified. This study investigated neural underpinnings of AD psychosis using surface-based-morphometry.Data from 32 AD patients, 17 with psychosis (AD-P) and 15 without were analyzed. Average cortical complexity (fractal dimension, FD) was estimated for each theoretically motivated ROI and patient. First, we compared regional FD in AD-P and AD patients. Then we calculated the correlation coefficients between FD and the severity of misidentification and paranoid psychotic symptoms. AD-P showed decreased FD in ventral-visual-stream compared to AD, suggesting that perceptual processes might be pivotal in psychosis. A negative correlation was found between misidentification severity and FD in the entorhinal cortex suggesting that misidentification may be specifically associated with alterations in regions involved in high-level perceptual and contextualization processes.

Temporal Variation in Disease Onset and Clinical Features of Lewy Body Disease in China

Background: Lewy body dementia is the second most common neurodegenerative dementia, but data concerning the onset age and clinical features in the prodromal stage remain limited in China. Objective: To investigate the associations between onset age and clinical manifestations of cognitive impairment with Lewy bodies in a large-sample cohort. Methods: We included 74 patients with mild cognitive impairment with Lewy bodies (MCI-LB), 533 patients with dementia with Lewy bodies (DLB), 118 patients with Parkinson’s disease with MCI (PD-MCI), and 313 patients with Parkinson’s disease dementia (PDD) in this multicenter cohort from 22 memory clinics of China from 1 January 2018 to 31 March 2022. The onset age, clinical manifestations, and neuropsychological assessments were recorded and analyzed after reviewing the medical records. Results: The average onset age of memory loss was 68.28 (±7.00) years, and parkinsonism happened 2.00 (±1.24) years later for patients with MCI-LB. The average onset age of parkinsonism was 60.56 (±8.96) years, and the memory loss happened 3.49 (±3.02) years later for patients with PD-MCI. Rapid eye movement sleep behavior disorder and visual hallucinations were frequently reported in MCI-LB, DLB, and PDD, while visual hallucinations were least frequently reported in PD-MCI. Lower scores of MMSE and depression, and higher scores of activities of daily living and delusions, were independently associated with older onset age in DLB. Conclusion: The onset of PD-MCI precedes MCI-LB, and memory loss occurs 3 years after parkinsonism. The onset age is associated with cognition and neuropsychiatric symptoms in process.

A Multimodal Neuroimaging and Neuropsychological Study of Visual Hallucinations in Alzheimer’s Disease

Background: Hallucinations in Alzheimer’s disease (AD) have been linked to more severe cognitive and functional decline. However, research on visual hallucinations (VH), the most common type of hallucinations in AD, is limited. Objective: To investigate the cognitive and cerebral macrostructural and metabolic features associated with VH in AD. Methods: Twenty-four AD patients with VH, 24 with no VH (NVH), and 24 cognitively normal (CN) matched controls were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Differences in regional gray matter (GM) volumes and cognitive performance were investigated with whole brain voxel-based morphometry analyses of MRI structural brain scans, and analyses of neuropsychological tests. Glucose metabolic changes were explored in a subsample of patients who had FDG-PET scans available. Results: More severe visuoconstructive and attentional deficits were found in AD VH compared with NVH. GM atrophy and hypometabolism were detected in occipital and temporal areas in VH patients in comparison with CN. On the other hand, NVH patients had atrophy and hypometabolism mainly in temporal areas. No differences in GM volume and glucose metabolism were found in the direct comparison between AD VH and NVH. Conclusion: In addition to the pattern of brain abnormalities typical of AD, occipital alterations were observed in patients with VH compared with CN. More severe visuoconstructive and attentional deficits were found in AD VH when directly compared with NVH, and might contribute to the emergence of VH in AD.

Psychosis as a Treatment Target in Dementia: A Roadmap for Designing Interventions

Psychotic phenomena are among the most severe and disruptive symptoms of dementias and appear in 30% to 50% of patients. They are associated with a worse evolution and great suffering to patients and caregivers. Their current treatments obtain limited results and are not free of adverse effects, which are sometimes serious. It is therefore crucial to develop new treatments that can improve this situation. We review available data that could enlighten the future design of clinical trials with psychosis in dementia as main target. Along with an explanation of its prevalence in the common diseases that cause dementia, we present proposals aimed at improving the definition of symptoms and what should be included and excluded in clinical trials. A review of the available information regarding the neurobiological basis of symptoms, in terms of pathology, neuroimaging, and genomics, is provided as a guide towards new therapeutic targets. The correct evaluation of symptoms is transcendental in any therapeutic trial and these aspects are extensively addressed. Finally, a critical overview of existing pharmacological and non-pharmacological treatments is made, revealing the unmet needs, in terms of efficacy and safety. Our work emphasizes the need for better definition and measurement of psychotic symptoms in dementias in order to highlight their differences with symptoms that appear in non-dementing diseases such as schizophrenia. Advances in neurobiology should illuminate the development of new, more effective and safer molecules for which this review can serve as a roadmap in the design of future clinical trials.

Sex Differences for Clinical Correlates of Alzheimer's Pathology in People with Lewy Body Pathology

BACKGROUND

Lewy body (LB) dementias have limited clinical diagnostic accuracy because of frequent copathologies contributing to clinical heterogeneity. Although sex differences in clinical prevalence and frequency of pure LB pathology were shown, differences for clinicopathological correlations are less known.

OBJECTIVE

The aim of this study was to determine sex differences for clinical associations of Alzheimer's disease (AD) copathology in those with LB pathology.

METHODS

Data were from National Alzheimer's Coordinating Center for 223 women and 468 men with limbic or neocortical LB, separated into two groups as those with high likelihood and low/intermediate likelihood for LB clinical phenotype based on pathology. Clinical associations of sex and interaction of sex and pathology for the clinical phenotype were analyzed.

RESULTS

More severe AD copathology was associated with worse cognitive decline and lower likelihood of LB disease clinical phenotype. Women with more severe AD copathology and tau had worse cognitive decline and higher likelihood of AD clinical phenotype than men. Men with more severe AD copathology had lower likelihood of LB clinical phenotype than women. Interaction of sex and pathology was more pronounced in those aged between 70 and 80 years.

CONCLUSIONS

AD copathology reduces the likelihood of LB clinical phenotype for both women and men; however, men may be at higher risk for LB disease underdiagnosis and women at higher risk for dementia. The use of both LB and AD biomarkers, even when LB or AD pathology is not clinically expected, is necessary for the accurate clinical diagnosis of both LB diseases and AD. © 2022 International Parkinson and Movement Disorder Society.

Paranoid and misidentification subtypes of psychosis in dementia

This study aimed to review the neurobiological and neuropsychological correlates of paranoid (persecutory delusions) and misidentification (misidentification delusions and/or hallucinations) subtypes of psychosis in dementia, to establish if they represent distinct subphenotypes. Nine studies were eligible, all included patients with Alzheimer's disease. Greater global cognitive deficits and an accelerated global cognitive decline were observed in the misidentification subtype. Neuroimaging studies showed more marked volume loss in multiple regions in patients with the misidentification subtype, including those involved in object recognition and the processing of information on spatial and temporal context. A single study found greater impairment in visual sustained attention and object recognition in the misidentification subtype. The small number of studies and methodological heterogeneity limit interpretation of the findings. Nevertheless, these findings would tentatively suggest that there may be additional or accelerated pathological change in functional networks involved in visuoperceptual processing in the misidentification subtype. This should be further explored in prospective studies and the investigation extended to other forms of dementia, to gain a transdiagnostic perspective.

Striatal Dopaminergic Depletion Pattern Reflects Pathological Brain Perfusion Changes in Lewy Body Diseases

PURPOSE

In Lewy body diseases (LBD), various symptoms occur depending on the distribution of Lewy body in the brain, and the findings of brain perfusion and dopamine transporter single-photon emission computed tomography (DAT-SPECT) also change accordingly. We aimed to evaluate the correlation between brain perfusion SPECT and quantitative indices calculated from DAT-SPECT in patients with LBD.

PROCEDURES

We retrospectively enrolled 35 patients with LBD who underwent brain perfusion SPECT with N-isopropyl-p-[¹²³I] iodoamphetamine and DAT-SPECT with ¹²³I-ioflupane. Mini-mental state examination (MMSE) data were also collected from 19 patients. Quantitative indices (specific binding ratio [SBR], putamen-to-caudate ratio [PCR], and caudate-to-putamen ratio [CPR]) were calculated using DAT-SPECT. These data were analysed by the statistical parametric mapping procedure.

RESULTS

In patients with LBD, decreased PCR index correlated with hypoperfusion in the brainstem (medulla oblongata and midbrain) (uncorrected p < 0.001, k > 100), while decreased CPR index correlated with hypoperfusion in the right temporoparietal cortex (family-wise error corrected p < 0.05), right precuneus (uncorrected p < 0.001, k > 100), and bilateral temporal cortex (uncorrected p < 0.001, k > 100). However, there was no significant correlation between decreased SBR index and brain perfusion. Additionally, the MMSE score was correlated with hypoperfusion in the left temporoparietal cortex (uncorrected p < 0.001).

CONCLUSIONS

This study suggests that regional changes in striatal ¹²³I-ioflupane accumulation on DAT-SPECT are related to brain perfusion changes in patients with LBD.

Sex Modifies the Associations of APOEɛ4 with Neuropsychiatric Symptom Burden in Both At-Risk and Clinical Cohorts of Alzheimer's Disease

BACKGROUND

Recent work suggests that APOEɛ4/4 females with Alzheimer's disease (AD) are more susceptible to developing neuropsychiatric symptoms (NPS).

OBJECTIVE

To examine the interaction of sex and APOEɛ4 status on NPS burden using two independent cohorts: 1) patients at risk for AD with mild cognitive impairment and/or major depressive disorder (n = 252) and 2) patients with probable AD (n = 7,261).

METHODS

Regression models examined the interactive effects of sex and APOEɛ4 on the number of NPS experienced and NPS Severity. APOEɛ3/4 and APOEɛ4/4 were pooled in the at-risk cohort due to the sample size.

RESULTS

In the at-risk cohort, there was a significant sex*APOEɛ4 interaction (p = 0.007) such that the association of APOEɛ4 with NPS was greater in females than in males (incident rate ratio (IRR) = 2.0). APOEɛ4/4 females had the most NPS (mean = 1.9) and the highest severity scores (mean = 3.5) of any subgroup. In the clinical cohort, APOEɛ4/4 females had significantly more NPS (IRR = 1.1, p = 0.001, mean = 3.1) and higher severity scores (b = 0.31, p = 0.015, mean = 3.7) than APOEɛ3/3 females (meanNPS = 2.9, meanSeverity = 3.3). No association was found in males.

CONCLUSION

Our study suggests that sex modifies the association of APOEɛ4 on NPS burden. APOEɛ4/4 females may be particularly susceptible to increased NPS burden among individuals with AD and among individuals at risk for AD. Further investigation into the mechanisms behind these associations are needed.

Neuropathology and molecular diagnosis of Synucleinopathies

Synucleinopathies are clinically and pathologically heterogeneous disorders characterized by pathologic aggregates of α-synuclein in neurons and glia, in the form of Lewy bodies, Lewy neurites, neuronal cytoplasmic inclusions, and glial cytoplasmic inclusions. Synucleinopathies can be divided into two major disease entities: Lewy body disease and multiple system atrophy (MSA). Common clinical presentations of Lewy body disease are Parkinson's disease (PD), PD with dementia, and dementia with Lewy bodies (DLB), while MSA has two major clinical subtypes, MSA with predominant cerebellar ataxia and MSA with predominant parkinsonism. There are currently no disease-modifying therapies for the synucleinopathies, but information obtained from molecular genetics and models that explore mechanisms of α-synuclein conversion to pathologic oligomers and insoluble fibrils offer hope for eventual therapies. It remains unclear how α-synuclein can be associated with distinct cellular pathologies (e.g., Lewy bodies and glial cytoplasmic inclusions) and what factors determine neuroanatomical and cell type vulnerability. Accumulating evidence from in vitro and in vivo experiments suggests that α-synuclein species derived from Lewy body disease and MSA are distinct "strains" having different seeding properties. Recent advancements in in vitro seeding assays, such as real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA), not only demonstrate distinct seeding activity in the synucleinopathies, but also offer exciting opportunities for molecular diagnosis using readily accessible peripheral tissue samples. Cryogenic electron microscopy (cryo-EM) structural studies of α-synuclein derived from recombinant or brain-derived filaments provide new insight into mechanisms of seeding in synucleinopathies. In this review, we describe clinical, genetic and neuropathologic features of synucleinopathies, including a discussion of the evolution of classification and staging of Lewy body disease. We also provide a brief discussion on proposed mechanisms of Lewy body formation, as well as evidence supporting the existence of distinct α-synuclein strains in Lewy body disease and MSA.

[Hallucinations in Patients with Idiopathic Parkinson's Disease]

Patients with idiopathic Parkinson's disease develop symptoms of the hallucination-psychosis spectrum in more than 20%. Most common are visual hallucinations. The pathogenesis of hallucinations mainly depends on disease duration, the distribution and extent of alpha-synuclein pathology, and modulating effects of the dopaminergic therapy. When managing PD hallucinations both anti-delirogenic actions and medication management are important. However, decrease in dopaminergic medication may lead to critical worsening of akinesia. If appropriate neuroleptic medication - essentially quetiapin or clozapin - can be considered. Instead, anti-dopaminergic neuroleptics should not be used owing to their pro-akinetic side-effects. Here, we provide therapy recommendations to manage PD hallucinations based on an up-to-date targeted review of the literature and expert-based empirical evidence.

Psychosis in neurodegenerative disease: differential patterns of hallucination and delusion symptoms

Although psychosis is a defining feature of Lewy body disease, psychotic symptoms occur in a subset of patients with every major neurodegenerative disease. Few studies, however, have compared disease-related rates of psychosis prevalence in a large autopsy-based cohort, and it remains unclear how diseases differ with respect to the nature or content of the psychosis. We conducted a retrospective chart review of 372 patients with autopsy-confirmed neurodegenerative pathology: 111 with Alzheimer's disease, 59 with Lewy body disease and concomitant Alzheimer's disease, 133 with frontotemporal lobar degeneration (FTLD) with tau inclusions (including progressive supranuclear palsy, corticobasal degeneration or Pick's disease), and 69 with FTLD and TDP inclusions (FTLD-TDP, including types A-C). Psychosis content was classified by subtype, and the frequency of each subtype was compared among pathological diagnoses using logistic regression. A total of 111 of 372 patients had psychosis. Compared to other groups, patients with Lewy body disease/Alzheimer's disease pathology were significantly more likely to have hallucinations and were more likely to have more than one subtype of hallucination. Patients with Braak Parkinson stage 5-6 Lewy body disease were significantly more likely than those with no Lewy body disease to have visual hallucinations of misperception, peripheral hallucinations, hallucinations that moved, hallucinations of people/animals/objects, as well as delusions regarding a place and delusions of misidentification. The feeling of a presence occurred significantly more frequently in patients with Lewy body disease/Alzheimer's disease than all other pathologies. Patients with FTLD-TDP were significantly more likely to have delusions, and for the delusions to occur in the first 3 years of the disease, when compared to patients with Alzheimer's disease and FTLD-tau, though rates were not significantly greater than patients with Lewy body disease/Alzheimer's disease. Paranoia occurred more frequently in the FTLD-TDP and Lewy body disease/Alzheimer's disease categories compared to patients with Alzheimer's disease or FTLD-tau. Patients with FTLD-TDP pathology had delusions of misidentification as frequently as patients with Lewy body disease/Alzheimer's disease, and were significantly more likely to have self-elevating delusions such as grandiosity and erotomania compared to patients with other pathologies including FTLD-tau. These data show that the nature and content of psychosis can provide meaningful information about the underlying neurodegenerative pathology, emphasizing the importance of characterizing patients' psychoses for prediction of the neuropathological diagnosis, regardless of a patient's clinical syndrome.

Visual hallucinations in psychiatric, neurologic, and ophthalmologic disease

PURPOSE OF REVIEW

Recent studies have increased our understanding of the biochemical and structural bases of visual hallucinations in patients with a variety of underlying causes.

RECENT FINDINGS

Visual hallucinations may be related to disruption of functional connectivity networks, with underlying biochemical dysfunction such as decreased in cholinergic activity. Structural abnormalities in primary and higher order visual processing areas also have been found in patients with visual hallucinations. The occurrence of visual hallucinations after vision loss, the Charles Bonnet syndrome, may have more functional similarity to psychiatric and neurodegenerative causes than previously suspected despite retained insight into the unreal nature of the phenomena.

SUMMARY

Visual hallucinations are common, and patients may not report them if specific inquiries are not made. Presence or absence of hallucinations may be of diagnostic and therapeutic importance, especially in patients with neurodegenerative conditions that have overlapping features. Treatment of visual hallucinations remains challenging and must be tailored to each patient based on the underlying cause and comorbid conditions.

Distinct clinicopathologic clusters of persons with TDP-43 proteinopathy

To better understand clinical and neuropathological features of TDP-43 proteinopathies, data were analyzed from autopsied research volunteers who were followed in the National Alzheimer's Coordinating Center (NACC) data set. All subjects (n = 495) had autopsy-proven TDP-43 proteinopathy as an inclusion criterion. Subjects underwent comprehensive longitudinal clinical evaluations yearly for 6.9 years before death on average. We tested whether an unsupervised clustering algorithm could detect coherent groups of TDP-43 immunopositive cases based on age at death and extensive neuropathologic data. Although many of the brains had mixed pathologies, four discernible clusters were identified. Key differentiating features were age at death and the severity of comorbid Alzheimer's disease neuropathologic changes (ADNC), particularly neuritic amyloid plaque densities. Cluster 1 contained mostly cases with a pathologic diagnosis of frontotemporal lobar degeneration (FTLD-TDP), consistent with enrichment of frontotemporal dementia clinical phenotypes including appetite/eating problems, disinhibition and primary progressive aphasia (PPA). Cluster 2 consisted of elderly limbic-predominant age-related TDP-43 encephalopathy (LATE-NC) subjects without severe neuritic amyloid plaques. Subjects in Cluster 2 had a relatively slow cognitive decline. Subjects in both Clusters 3 and 4 had severe ADNC + LATE-NC; however, Cluster 4 was distinguished by earlier disease onset, swifter disease course, more Lewy body pathology, less neocortical TDP-43 proteinopathy, and a suggestive trend in a subgroup analysis (n = 114) for increased C9orf72 risk SNP rs3849942 T allele (Fisher's exact test p value = 0.095). Overall, clusters enriched with neocortical TDP-43 proteinopathy (Clusters 1 and 2) tended to have lower levels of neuritic amyloid plaques, and those dying older (Clusters 2 and 3) had far less PPA or disinhibition, but more apathy. Indeed, 98% of subjects dying past age 85 years lacked clinical features of the frontotemporal dementia syndrome. Our study revealed discernible subtypes of LATE-NC and underscored the importance of age of death for differentiating FTLD-TDP and LATE-NC.

Prevalence and clinical associations of tau in Lewy body dementias: A systematic review and meta-analysis

INTRODUCTION

Alzheimer's disease neuropathologies (amyloid-β and tau) frequently co-exist to varying degrees in Lewy body dementias (LBD), which include dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).

OBJECTIVES

To investigate the prevalence of tau in DLB and PDD, and its associations with clinical outcomes.

METHODS

We searched the major electronic databases using the search term: ("dementia with Lewy bodies" OR "diffuse Lewy body disease" OR "Lewy body variant of Alzheimer's disease") AND ("tau protein" OR "tauopathy" OR "neurofibrillary tangle"), for relevant studies which evaluated tau in LBD. Forty-nine articles met the inclusion criteria for data extraction. Where appropriate, a random-effect meta-analysis was performed to obtain pooled estimates for prevalence and risk ratios (RR) or standardized mean differences (SMD) for clinical features, diagnostic accuracy and cognition.

RESULTS

Braak neurofibrillary tangle stage ≥ III was observed in 66% (n = 1511, 95%CI 60%-73%) of DLB and 52% (n = 433, 95%CI 27%-76%) of PDD at autopsy. Abnormal CSF phosphorylated-tau levels were present in 28% (n = 925, 95%CI 25%-31%) of DLB and 15% (n = 172, 95%CI 5%-24%) of PDD cases. Higher tau burden in DLB was associated with reduced likelihood of manifesting visual hallucinations (RR 0.56; 95%CI 0.40-0.77) and motor parkinsonism (RR 0.62; 95%CI 0.40-0.98), lower diagnostic accuracy of DLB during life (RR 0.49; 95%CI 0.38-0.64) and worse cognition prior to death (SMD 0.63; 95%CI 0.46-0.81).

CONCLUSIONS

Tau is common in LBD and may reduce clinical diagnostic accuracy in people with DLB. Prospective longitudinal studies are needed to understand the roles of co-morbid neuropathologies in Lewy body dementias.

Prevalence and Clinical Implications of the Mirror and TV Signs in Advanced Alzheimer's Disease and Dementia with Lewy Bodies

Objective

To explore the prevalence and clinical implications of the mirror and TV signs in the moderate to advanced stages of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB).

Methods

We retrospectively examined the prevalence of clinical and psychiatric symptoms including the mirror and TV signs in 200 subjects with AD and 200 with DLB and evaluated the relationships among the symptoms.

Results

The mirror sign was found in 3.0% of AD and 4.5% of DLB subjects. The TV sign was found in 1.5% of AD and 4.0% of DLB subjects. The prevalence of the mirror and TV signs was not significantly different between the AD and DLB groups. Visual hallucination, visual illusion, misidentification of person, and sleep talking were significantly more frequent in DLB than in AD subjects. The mirror sign was significantly associated with lower Mini-Mental State Examination scores, whereas the TV sign was significantly associated with the misidentification of person.

Conclusions

Both the mirror and TV signs were rare even in the moderate to advanced stages of AD and DLB. The mirror sign may be independent from other delusional misidentification syndromes (DMSs). Being associated mainly with global cognitive decline, the mirror sign is unlikely attributed to any specific cognitive impairment or the dysfunction of localized brain areas. In contrast, the TV sign was significantly more often coexistent with the misidentification of person, suggesting that the TV sign may partly share common neuropsychological mechanisms with DMSs.

Visual hallucinations in Alzheimer's disease do not seem to be associated with chronic hypoperfusion of to visual processing areas V2 and V3 but may be associated with reduced cholinergic input to these areas

Background

Up to 20% of patients with AD experience hallucinations. The pathological substrate is not known. Visual hallucinations (VH) are more common in dementia with Lewy bodies (DLB). In autopsy studies, up to 60% of patients with AD have concomitant Lewy body pathology. Decreased perfusion of the occipital lobe has been implicated in DLB patients with VH, and post-mortem studies point to both decreased cholinergic activity and reduced oxygenation of the occipital cortex in DLB.

Methods

We used biochemical methods to assess microvessel density (level of von Willebrand factor, a marker of endothelial cell content), ante-mortem oxygenation (vascular endothelial growth factor, a marker of tissue hypoxia; myelin-associated glycoprotein to proteolipid protein-1 ratio, a measure of tissue oxygenation relative to metabolic demand), cholinergic innervation (acetylcholinesterase and choline acetyltransferase), butyrylcholinesterase and insoluble α-synuclein content in the BA18 and BA19 occipital cortex obtained post-mortem from 23 AD patients who had experienced visual hallucinations, 19 AD patients without hallucinations, 19 DLB patients, and 36 controls. The cohorts were matched for age, gender and post-mortem interval.

Results

There was no evidence of reduced microvessel density, hypoperfusion or reduction in ChAT activity in AD with visual hallucinations. Acetylcholinesterase activity was reduced in both BA18 and BA19, in all 3 dementia groups, and the concentration was also reduced in BA19 in the DLB and AD without visual hallucinations groups. Insoluble α-synuclein was raised in the DLB group in both areas but not in AD either with or without visual hallucinations.

Conclusions

Our results suggest that visual hallucinations in AD are associated with cholinergic denervation rather than chronic hypoperfusion or α-synuclein accumulation in visual processing areas of the occipital cortex.

Electronic supplementary material

The online version of this article (10.1186/s13195-019-0519-7) contains supplementary material, which is available to authorized users.

Clinicopathologic subtype of Alzheimer's disease presenting as corticobasal syndrome

INTRODUCTION

The corticobasal syndrome (CBS) is associated with several neuropathologic disorders, including corticobasal degeneration and Alzheimer's disease (AD).

METHOD

In this report, we studied 43 AD patients with CBS (AD-CBS) and compared them with 42 AD patients with typical amnestic syndrome (AD-AS), as well as 15 cases of corticobasal degeneration and CBS pathology.

RESULTS

Unlike AD-AS, AD-CBS had prominent motor problems, including limb apraxia (90%), myoclonus (81%), and gait disorders (70%). Alien limb phenomenon was reported in 26% and cortical sensory loss in 14%. Language problems were also more frequent in AD-CBS, and memory impairment was less frequent. AD-CBS had more tau pathology in perirolandic cortices but less in superior temporal cortex than AD-AS. In addition, AD-CBS had greater neuronal loss in the substantia nigra.

DISCUSSION

AD-CBS is a clinicopathological subtype of AD with an atypical distribution of Alzheimer-type tau pathology. Greater neuronal loss in the substantia nigra may contribute to Parkinsonism which is not a feature of typical AD.

Differences in the Experience of Caregiving Between Spouse and Adult Child Caregivers in Dementia With Lewy Bodies

BACKGROUND AND OBJECTIVES

Dementia caregiving has been associated with increased burden, depression, grief, a decreased sense of well-being and quality of life, and a weakening of social support. Little is known about the experience of caregiving in Dementia with Lewy Bodies (DLB). The present study examines differences in the caregiving experience of spouse versus adult child caregivers of individuals with DLB.

RESEARCH DESIGN AND METHODS

In this cross-sectional analytic study of spouses (n = 255) and adult children (n = 160) caregivers of individuals with DLB, participants completed an online survey of burden, grief, depression, well-being, quality of life, and social support.

RESULTS

Adult child caregivers were more likely to care for women (p < .001) and see the care recipient less often (p < .001) than spouses. Adult child caregivers reported lower quality of life (p < .001) and more caregiver burden (p < .009), but also greater social support (p < .001) than spouses. Between group analyses of caregiver type by disease severity demonstrated that spousal caregivers experience greater grief with advancing disease (p = .005), while adult child caregivers increase social support with advancing disease (p < .001).

DISCUSSION AND IMPLICATIONS

Spouses and adult children experience DLB caregiving differently. This was explained by the younger age of the adult child caregiver, frequency of contact with the care recipient, and differences in the care recipient's characteristics, frequency of neuropsychiatric symptoms, and disease severity. DLB caregiver support for this population should target psychoeducation for complicated neuropsychiatric symptoms in the care recipient. Screening all DLB caregivers for burden, grief, and depression is suggested to identify those that may benefit most from intervention. Spouses specifically may benefit from interventions that target increasing social support, while adult child caregivers may benefit from interventions aimed at mitigating burden and improving quality of life.

Review: Clinical, neuropathological and genetic features of Lewy body dementias

Lewy body dementias are the second most common neurodegenerative dementias after Alzheimer's disease and include dementia with Lewy bodies and Parkinson's disease dementia. They share similar clinical and neuropathological features but differ in the time of dementia and parkinsonism onset. Although Lewy bodies are their main pathological hallmark, several studies have shown the emerging importance of Alzheimer's disease pathology. Clinical amyloid-β imaging using Pittsburgh Compound B (PiB) supports neuropathological studies which found that amyloid-β pathology is more common in dementia with Lewy bodies than in Parkinson's disease dementia. Nevertheless, other co-occurring pathologies, such as cerebral amyloid angiopathy, TDP-43 pathology and synaptic pathology may also influence the development of neurodegeneration and dementia. Recent genetic studies demonstrated an important role of APOE genotype and other genes such as GBA and SNCA which seem to be involved in the pathophysiology of Lewy body dementias. The aim of this article is to review the main clinical, neuropathological and genetic aspects of dementia with Lewy bodies and Parkinson's disease dementia. This is particularly relevant as future management for these two conditions may differ.

Misidentification Subtype of Alzheimer's Disease Psychosis Predicts a Faster Cognitive Decline

The presence of psychosis is associated with a more rapid decline in Alzheimer's disease (AD), but the impact of paranoid (persecutory delusions) and misidentification (misperceptions and/or hallucinations) subtypes of psychosis on the speed of decline in AD is still unclear. We analyzed data on Alzheimer's Disease Neuroimaging Initiative 2 participants with late mild cognitive impairment or AD, and we described individual trajectories of Alzheimer's Disease Assessment Scale-Cognitive Subscale scores using a semimechanistic logistic model with a mixed effects-based approach, which accounted for dropout and adjusted for baseline Mini Mental State Examination scores. The covariate model included psychosis subtypes, age, gender, education, medications, and Apolipoprotein E epsilon 4 (Apo-e ε4 genotype). We found that the Alzheimer's Disease Assessment Scale-Cognitive Subscale rate of increase was doubled in misidentification (β_{r,misid_subtype}  = 0.63, P = 0.031) and mixed (both subtypes; β_{r,mixed_subtype}  = 0.70, P = 0.003) when compared with nonpsychotic (or paranoid) patients, suggesting that the misidentification subtype may represent a distinct AD sub-phenotype associated with an accelerated pathological process.

Reduced occipital GABA in Parkinson disease with visual hallucinations

Objective

To investigate the relationship between visual hallucinations in Parkinson disease (PD) and levels of γ-aminobutyric acid (GABA) in the primary visual cortex.

Methods

We utilized magnetic resonance spectroscopy to investigate occipital GABA levels in 36 participants with PD, 19 with and 17 without complex visual hallucinations, together with 20 healthy controls without hallucinations. In addition, we acquired T1-weighted MRI, whole-brain fMRI during a visual task, and diffusion tensor imaging.

Results

We found lower GABA+/creatine in PD with visual hallucinations (0.091 ± 0.010) vs those without (0.101 ± 0.010) and controls (0.099 ± 0.010) (F_2,49 = 4.5; p = 0.016). Reduced gray matter in the hallucinations group was also observed in the anterior temporal lobe. Although there were widespread reductions in white matter integrity in the visual hallucinations group, this was no longer significant after controlling for cognitive function.

Conclusions

The data suggest that reduced levels of GABA are associated with visual hallucinations in PD and implicate changes to the ventral visual stream in the genesis of visual hallucinations. Modulation of visual cortical excitability through, for example, pharmacologic intervention, may be a promising treatment avenue to explore.

Quality of Life in Patients with Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is a complex, multisymptom disorder. When making decisions regarding the treatment of DLB, the patient's quality of life (QoL) should always be the main consideration. To our knowledge, this is the first review article focusing on the QoL in DLB patients. We searched the PubMed database using the keywords "quality of life" and "dementia with Lewy bodies." Previously, no specific instrument had been developed for assessing the QoL in DLB patients. Patients with DLB have a decreased QoL compared to patients with Alzheimer's disease, which is reportedly caused by several factors including level of independence in instrumental activities of daily living, whether the patient is living with the caregiver, apathy, delusion, and dysautonomia. The direct effect of visual hallucination, sleep, and movement disorders on the QoL in DLB patients has not been previously studied. The role of cognitive function on the QoL is still controversial. In a randomized controlled study, memantine may improve the QoL in PDD or DLB patients. We concluded that it is important to develop a specific instrument to assess the QoL in DLB patients. Furthermore, there is an urgent need for large clinical trials to identify factors associated with the QoL and how they can be managed.

Compensatory shifts in visual perception are associated with hallucinations in Lewy body disorders

Visual hallucinations are a common, distressing, and disabling symptom of Lewy body and other diseases. Current models suggest that interactions in internal cognitive processes generate hallucinations. However, these neglect external factors. Pareidolic illusions are an experimental analogue of hallucinations. They are easily induced in Lewy body disease, have similar content to spontaneous hallucinations, and respond to cholinesterase inhibitors in the same way. We used a primed pareidolia task with hallucinating participants with Lewy body disorders (n = 16), non-hallucinating participants with Lewy body disorders (n = 19), and healthy controls (n = 20). Participants were presented with visual “noise” that sometimes contained degraded visual objects and were required to indicate what they saw. Some perceptions were cued in advance by a visual prime. Results showed that hallucinating participants were impaired in discerning visual signals from noise, with a relaxed criterion threshold for perception compared to both other groups. After the presentation of a visual prime, the criterion was comparable to the other groups. The results suggest that participants with hallucinations compensate for perceptual deficits by relaxing perceptual criteria, at a cost of seeing things that are not there, and that visual cues regularize perception. This latter finding may provide a mechanism for understanding the interaction between environments and hallucinations.

Clinical and neurocognitive aspects of hallucinations in Alzheimer's disease

Due to their prevalence, hallucinations are considered as one of the most frequent psychotic symptoms in Alzheimer's disease (AD). These psychotic manifestations reduce patients' well-being, increase the burden of caregivers, contribute to early institutionalization, and are related with the course of cognitive decline in AD. Considering their consequences, we provide a comprehensive account of the current state of knowledge about the prevalence and characteristics of hallucinations in AD. We propose a comprehensive and testable theoretical model about hallucinations in AD: the ALZHA (ALZheimer and HAllucinations) model. In this model, neurological, genetic, cognitive, affective, and iatrogenic factors associated with hallucinations in AD are highlighted. According to the ALZHA model, hallucinations in AD first involve trait markers (i.e., cognitive deficits, neurological deficits, genetic predisposition and/or sensory deficits) to which state markers that may trigger these experiences are added (e.g., psychological distress and/or iatrogenic factors). Finally, we provide recommendations for assessment and management of these psychotic manifestations in AD, with the aim to benefit patients, caregivers, and health professionals.

Analysis of primary visual cortex in dementia with Lewy bodies indicates GABAergic involvement associated with recurrent complex visual hallucinations

Dementia with Lewy bodies (DLB) patients frequently experience well formed recurrent complex visual hallucinations (RCVH). This is associated with reduced blood flow or hypometabolism on imaging of the primary visual cortex. To understand these associations in DLB we used pathological and biochemical analysis of the primary visual cortex to identify changes that could underpin RCVH. Alpha-synuclein or neurofibrillary tangle pathology in primary visual cortex was essentially absent. Neurone density or volume within the primary visual cortex in DLB was also unchanged using unbiased stereology. Microarray analysis, however, demonstrated changes in neuropeptide gene expression and other markers, indicating altered GABAergic neuronal function. Calcium binding protein and GAD65/67 immunohistochemistry showed preserved interneurone populations indicating possible interneurone dysfunction. This was demonstrated by loss of post synaptic GABA receptor markers including gephyrin, GABARAP, and Kif5A, indicating reduced GABAergic synaptic activity. Glutamatergic neuronal signalling was also altered with vesicular glutamate transporter protein and PSD-95 expression being reduced. Changes to the primary visual cortex in DLB indicate that reduced GABAergic transmission may contribute to RCVH in DLB and treatment using targeted GABAergic modulation or similar approaches using glutamatergic modification may be beneficial.

Clinicopathological correlation of psychosis and brain vascular changes in Alzheimer's disease

Psychosis is common in Alzheimer’s disease (AD). However, studies on neuropathology in vascular etiology contributing to psychosis in AD is lacking to date. The aim of this study was to investigate neuropathological vascular related changes in Alzheimer’s disease with psychosis. Data of patients with AD from the National Alzheimer’s Coordinating Center between 2005 to September 2013 was accessed and reviewed. Presence of psychosis was determined based on Neuropsychiatric Inventory Questionnaire taken from the last visit within one year prior to death, and patients were divided into psychosis positive and negative group. Comparison of clinical details and neuropathological vascular changes between the groups was performed using Wilcoxon rank sum test and Chi-square/ Fisher’s exact test. Significant variables were further included in a multivariate logistic model. Overall, 145 patients was included. Of these, 50 patients were psychosis positive. Presence of one or more cortical microinfarcts and moderate to severe arteriosclerosis was found to be positively associated with psychosis. Our results suggest vascular changes correlate with psychosis in Alzheimer’s disease.

Cognitive phenotype of psychotic symptoms in Alzheimer's disease: evidence for impaired visuoperceptual function in the misidentification subtype

BACKGROUND

Establishing the cognitive phenotype of psychotic symptoms in Alzheimer's disease (AD) could localise discrete pathology and target symptomatic treatment. This study aimed to establish whether psychotic symptoms would be associated with poorer performance on neuropsychological tests known to correlate with striatal dopaminergic function and to investigate whether these differences would be attributed to the paranoid (persecutory delusions) or misidentification (misidentification phenomena +/- hallucinations) subtype.

METHODS

Seventy patients with probable AD (34 psychotic and 36 nonpsychotic) were recruited to the study. Analysis of covariance was used to compare motor speed and the rapid visual processing test of sustained visual attention, after adjusting for potential confounding factors. Multivariate analyses were used to compare performance across other cognitive domains. Significant findings were explored by separating patients on the basis of subtype.

RESULTS

Rapid visual processing performance accuracy was reduced in patients with psychotic symptoms (F1,58  = 5.94, p = 0.02) and differed significantly across subtypes (F2,51  = 3.94, p = 0.03), largely because of poorer performance in the misidentification compared with nonpsychotic group. Multivariate analyses (corrected for multiple comparisons) showed poorer performance on the incomplete letters task in psychotic patients (F1,63  = 8.77, p = 0.004) and across subtypes (F2,55  = 10.90, p < 0.001), similarly attributed to the misidentification subtype.

CONCLUSIONS

These findings provide further support of the involvement of dopaminergic networks in the psychosis endophenotype in AD and, in addition, implicate the ventral (temporo-occipital) pathway in the misidentification subtype. Future studies should investigate the early trajectory of neuropathological change in vivo across psychosis subtypes.

Psychosis in Later Life: A Review and Update

Psychosis is relatively common in later life and can present in a wide variety of contexts, including early-onset and late-onset schizophrenia, delusional disorder, mood disorders, and various dementias. It can also occur as the result of numerous medical and neurological diseases and from the use of certain medications. Although identifying the cause of psychosis in older patients can be challenging, the unique clinical features associated with the different disorders can help in making the diagnosis. Accurate diagnosis of psychosis in older populations is essential, as its treatment varies depending on the context in which it appears. Despite the safety concerns regarding the use of antipsychotics in older patients, certain pharmacological treatments appear to be both efficacious and reasonably safe in treating psychosis in older populations. Additionally, although research is limited, numerous psychosocial therapies appear promising. This review summarizes the literature on the epidemiology, clinical characteristics, neuroimaging, and treatment of psychosis in later life, and serves as an update to past reviews on this topic.

Molecular imaging biomarkers for dementia with Lewy bodies: an update

BACKGROUND

Dementia with Lewy body (DLB) is considered to be the second most common form of neurodegenerative disorders after Alzheimer's disease (AD), affecting as many as 100,000 people in the UK and up to 1.3 million in the USA. However, nearly half of patients with DLB remain undiagnosed thus depriving many of them from an early and adequate treatment of their distressing symptoms. Accurate and early diagnosis of DLB is important for both patients and their caregivers, since the neuropsychiatric symptoms require specific management.

METHODS

In the current study, we review the most recent developments in the field of molecular nuclear imaging to diagnose DLB.

RESULTS

The review addresses, the neurotransmitter based (dopaminergic, cholinergic, and glutamatergic) nuclear imaging techniques, role of the autonomic dysfunction and its visualization in DLB with myocardial sympathetic imaging and vesicular catecholamine uptake, as well as the use of amyloid polypeptides and glial markers as molecular imaging probes in the clinical diagnosis of DLB.

CONCLUSIONS

Most of the above nuclear imaging methods are restricted to highly specialized clinical centers, and thus not applicable to a large number of patients requiring dementia (e.g. DLB) diagnosis in routine clinical setting. Validating them against more readily accessible peripheral biomarkers, e.g. CSF and blood biomarkers linked to the DLB process, may facilitate their use in wider clinical settings.

Lewy body dementia: the impact on patients and caregivers

Lewy body dementia (LBD) is the second most common neurodegenerative dementia in older adults, yet there remains a delay in diagnosis that limits healthcare providers’ ability to maximize therapeutic outcomes and enhance patient and caregiver quality of life. The impact of LBD on patients includes limiting the potential exposure to medications that may cause adverse outcomes, and addressing how the disease manifestations, such as autonomic features and behavior, affect quality of life. LBD impact on caregivers has been discussed to a greater degree in the literature, and there is clear evidence of caregiver burden and grief associated with disease manifestations. Other common caregiving concerns, such as access to care, prevention of hospitalization, managing behavior, and reviewing prognosis and nursing home placement, are important to comprehensively address the needs of patients with LBD and their caregivers.

Three presenile patients in which neuropsychological and neuroimaging examinations suggest possible progression to dementia with Lewy bodies

We report three presenile patients who were initially suspected of having Alzheimer's disease (AD) or being in the prodromal stage of AD, regardless of visuoperceptual dysfunctions in daily living, because they lacked the core features and prodromal non-motor symptoms of dementia with Lewy bodies. Subsequently, progression to dementia with Lewy bodies was suspected based on neuropsychological and neuroimaging findings; additionally, one of the three patients suffered from visual hallucinations. Neuropsychological examinations such as subjective contours, cube copying and block design in the Wechsler Adult Intelligence Scale-III revealed visuoperceptual dysfunction in all three patients even when other cognitive functions were rather preserved. Brain magnetic resonance imaging revealed no significant brain atrophy, including in the parieto-occipital area and the hippocampus, while brain (18)F-fluorodeoxyglucose positron emission tomography demonstrated right dominant metabolic reductions in the occipital lobe, including the primary visual cortex, in all three patients. We suggest the possibility of progression to dementia with Lewy bodies, but not AD or posterior cortical atrophy. Regardless of the presence of core features and prodromal non-motor symptoms, this progression is suggested when there are difficulties only in higher-level visual processing such as subjective contours and block design in the Wechsler Adult Intelligence Scale-III, no significant atrophy of the parieto-occipital area and hippocampus on brain magnetic resonance imaging, and hypometabolism in the occipital lobe including the primary visual cortex on brain (18)F-fluorodeoxyglucose positron emission tomography.