Investigation of neuropsychological characteristics of very mild and mild dementia with Lewy bodies

Visuospatial dysfunction predicts dementia-first phenoconversion in isolated REM sleep behaviour disorder

OBJECTIVE

While isolated rapid eye movement sleep behaviour disorder (iRBD) is known as a prodrome of α-synucleinopathies, the prediction for its future phenoconversion to parkinsonism-first or dementia-first subtype remains a challenge. This study aimed to investigate whether visuospatial dysfunction predicts dementia-first phenoconversion in iRBD.

METHODS

Patients with iRBD and control subjects were enrolled in this prospective cohort study. Baseline neuropsychological assessment included the Unified Parkinson's Disease Rating Scale part III, Montreal Cognitive Assessment (MoCA), Rey-Osterrieth complex figure (ROCF), Colour Trails test (CTT), Farnsworth-Munsell 100-hue test and Digit Span test. The anterior and posterior subscores of MoCA as well as their modified versions were explored. A composite score derived from ROCF and CTT was also explored. Regular follow-up was conducted to determine the phenoconversion status of iRBD patients.

RESULTS

The study included 175 iRBD patients and 98 controls. During a mean follow-up of 5.1 years, 25.7% of patients experienced phenoconversion. Most of the neuropsychological tests could differentiate dementia-first but not parkinsonism-first convertors from non-convertors. The modified posterior subscore of MoCA, by integrating the Alternating Trail Making and Clock Drawing components into original the posterior subscore, which mainly reflects visuospatial function, was the strongest predictor for dementia-first phenoconversion (adjusted HR 5.48, 95% CI 1.67 to 17.98).

CONCLUSION

Visuospatial dysfunction, as reflected mainly by the modified posterior subscore of MoCA, is a predictive factor for dementia-first phenoconversion in iRBD, suggesting its potential for being a biomarker for clinical prognostic prediction and potential neuroprotective trials aiming to delay or prevent dementia.

Cognitive profile in mild cognitive impairment with Lewy bodies

Introduction

This study aimed to elucidate the cognitive profile of patients with mild cognitive impairment with Lewy bodies (MCI-LB) and to compare it to that of patients with mild cognitive impairment due to Alzheimer's disease (MCI-AD).

Methods

Subjects older than 60 years with probable MCI-LB (n = 60) or MCI-AD (n = 60) were recruited. All patients were tested with Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) to assess their global cognitive profile.

Results

The MCI-AD and MCI-LB patients did not differ in total MMSE and MoCA scores. However, some sub-items in MMSE and MoCA were shown to be screening markers for differentiating MCI-LB from MCI-AD. In the visuoconstructive test, the total score and hands subitem score in the clock-drawing test were significantly lower in MCI-LB than in MCI-AD. As for the executive function, the 'animal fluency test', 'repeat digits backward test' and 'take paper by your right hand' in MMSE all showed lower scores in MCI-LB compared with MCI-AD. As for memory, 'velvet' and 'church' in MoCA and 'ball' and 'national flag' in MMSE had lower scores in MCI-AD than in MCI-LB.

Conclusion

This study presents the cognitive profile of patients with MCI-LB. In line with the literature on Dementia with Lewy bodies, our results showed lower performance on tests for visuoconstructive and executive function, whereas memory remained relatively spared in the early period.

A Systematic Review and Comparison of Neurocognitive Features of Late-Life Attention-Deficit/Hyperactivity Disorder and Dementia With Lewy Bodies

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) in adulthood and dementia with Lewy bodies (DLB) share many cognitive and noncognitive similarities. The overlapping features between both disorders complicate differential diagnosis. The aim of the current systematic review was to compare patterns of neuropsychological profiles in older adults with ADHD and DLB.

METHOD

Of the 1989 ADHD-related articles and 1332 DLB-related articles screened, 3 ADHD and 25 DLB articles were retained for qualitative synthesis and review.

RESULTS

A synthesis of individual study findings revealed isolated working memory deficits for late-life ADHD, and performance deficits in areas of attention, memory, language, and visuoperceptual abilities for DLB. Results were limited by small samples and absence of data in some cognitive domains.

CONCLUSION

These initial findings support potentially unique neurocognitive profiles for ADHD in later life and DLB that would enable practitioners to differentially diagnose and appropriately treat older adults presenting with these phenotypically similar disorders.

Magnetic Resonance Imaging Texture of Medial Pulvinar in Dementia with Lewy Bodies

INTRODUCTION

Executive dysfunction is common in dementia with Lewy bodies (DLB). The pulvinar nucleus plays a role in executive control and synchronizes with cortical regions in the salience network that are vulnerable to Lewy pathology.

OBJECTIVE

We investigated the pulvinar subregions in patients with mild DLB and their associations with executive function.

METHODS

The sample consisted of 38 DLB patients and 38 age- and sex-matched normal controls. We evaluated cognitive function using the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet. We obtained four pulvinar nuclei using preprocessed T1-weighted magnetic resonance images. We compared volumes and textures of the DLB patients and the normal controls for each nucleus. We used a linear regression to determine the association of textures and neuropsychological test scores.

RESULTS

The DLB patients showed comparable volumes to the normal controls in all pulvinar nuclei. However, the DLB patients showed different texture of the left medial pulvinar (PuM) from the normal controls. The entropy, contrast, and cluster shade were lower but autocorrelation of left PuM was higher in the DLB patients compared to the normal controls. These texture features of the left PuM were associated with the set-shifting performance measured by the Trail Making Test.

CONCLUSIONS

In DLB, the left PuM may be altered from early stage, which may contribute to the development of executive dysfunction.

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.

Pay attention to the basal ganglia: a volumetric study in early dementia with Lewy bodies

BACKGROUND

Cortical and subcortical cognitive impairments are usually found in dementia with Lewy bodies (DLB). Roughly, they comprise visuo-constructive/executive function and attention/processing speed impairments, whereas memory would remain relatively spared. In this study, we focused on the neuro-anatomical substrates of attention and processing speed, which is still poorly understood. For the purpose of the study, we examined the correlations between behavioral scores measuring the speed of processing and the degree of cerebral atrophy in patients with prodromal to moderate DLB.

METHODS

Ninety-three prodromal to moderate DLB patients (mean MMSE = 25.5) were selected to participate in the study as well as 28 healthy elderly subjects (mean MMSE = 28.9), matched in terms of age and educational level. The Trail Making Test A (TMTA) and the Digit Symbol Substitution Test (DSST) were used to assess attention and processing speed. Behavioral performances were compared between patients and healthy control subjects. Three-dimensional MRI images were acquired for all participants, and correlational analyses were performed in the patient group using voxel-based morphometry (VBM).

RESULTS

The behavioral results on both the TMTA (p = .026) and the DSST (p < .001) showed significantly impaired performances in patients in comparison with control subjects. In addition, correlational analyses using VBM revealed for the TMTA negative correlations in the caudate nucleus (left cluster peak significant at .05 FWE corrected), the putamen, the left thalamus, and the subthalamic nuclei (p < .05 FDR corrected). Some positive correlations associated with the DSST were found in the right inferior frontal gyrus, the left thalamus, and the left cerebellum (p < .001 uncorrected).

CONCLUSIONS

The behavioral results are in line with the literature on the DLB cognitive profile and confirm the existence of attention and processing speed impairment. Interestingly, VBM analysis revealed the involvement of the basal ganglia, in particular, the left caudate nucleus, which is part of the attention cerebral network, suggesting an important role of this structure for attentional processing speed. This also suggests the clinical implication of damage in this region relatively early in the course of the disease.

The Neuropsychological Profile and Phenomenology of Late Onset Psychosis: A Cross-sectional Study on the Differential Diagnosis of Very-Late-Onset Schizophrenia-Like Psychosis, Dementia with Lewy Bodies and Alzheimer's Type Dementia with Psychosis

Objective

Late onset psychosis not only occurs as a prodromal symptom to neurodegeneration, but it can also be associated with a non-progressive mild cognitive deficit. Studying the phenomenology of psychotic symptoms and the neuropsychological profile may serve as sensitive and non-invasive tools for differential diagnosis.

Method

We compared 57 individuals with very-late-onset schizophrenia-like psychosis (VLOSLP), 49 participants with Dementia with Lewy Bodies (DLB) and 35 patients with Alzheimer's type Dementia and psychosis (AD+P) concerning the phenomenology of psychotic symptoms and the neuropsychological profile using several measures of cognitive function in a cross-sectional study.

Results

Participants with DLB exhibited more visual hallucinations, especially those involving animals, and less partition/paranoid delusions than both other groups. VLOSLP showed more partition delusions and auditory hallucinations of human voices than both other groups. Hence, patients with DLB and VLOSLP showed greater dissimilarity in the phenomenology of psychosis, whereas individuals with AD+P held an intermediate position. Processing speed and executive function were comparably impaired among the three groups, as was expected considering a common underlying set of neurobiological abnormalities for psychosis. However, AD+P showed more strongly reduced learning and consolidation skills, whereas DLB was associated with prominent visuoconstructive deficits.

Conclusions

Phenomenology of psychosis may prove especially informative when comparing individuals with DLB to those with VLOSLP. Neuropsychological profiles are able to further aid differential diagnosis of the three groups.

Verbal adynamia in parkinsonian syndromes: behavioral correlates and neuroanatomical substrate

Verbal adynamia (impaired language generation, as during conversation) has not been assessed systematically in parkinsonian disorders. We addressed this in patients with Parkinson's dementia, progressive supranuclear palsy and corticobasal degeneration. All disease groups showed impaired verbal fluency and sentence generation versus healthy age-matched controls, after adjusting for general linguistic and executive factors. Dopaminergic stimulation in the Parkinson's group selectively improved verbal generation versus other cognitive functions. Voxel-based morphometry identified left inferior frontal and posterior superior temporal cortical correlates of verbal generation performance. Verbal adynamia warrants further evaluation as an index of language network dysfunction and dopaminergic state in parkinsonian disorders.

Rapid eye movement sleep behavior disorder and the link to alpha-synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) involves REM sleep without atonia in conjunction with a recurrent nocturnal dream enactment behavior, with vocalizations such as shouting and screaming, and motor behaviors such as punching and kicking. Secondary RBD is well described in association with neurological disorders including Parkinson's disease (PD), multiple system atrophy (MSA), and other conditions involving brainstem structures such as tumors. However, RBD alone is now considered to be a potential harbinger of later development of neurodegenerative disorders, in particular PD, MSA, dementia with Lewy bodies (DLB), and pure autonomic failure. These conditions are linked by their underpinning pathology of alpha-synuclein protein aggregation. In RBD, it is therefore important to recognize the potential risk for later development of an alpha-synucleinopathy, and to investigate for other potential causes such as medications. Other signs and symptoms have been described in RBD, such as orthostatic hypotension, or depression. While it is important to recognize these features to improve patient management, they may ultimately provide clinical clues that will lead to risk stratification for phenoconversion. A critical need is to improve our ability to counsel patients, particularly with regard to prognosis. The ability to identify who, of those with RBD, is at high risk for later neurodegenerative disorders will be paramount, and would in addition advance our understanding of the prodromal stages of the alpha-synucleinopathies. Moreover, recognition of at-risk individuals for neurodegenerative disorders may ultimately provide a platform for the testing of possible neuroprotective agents for these neurodegenerative disorders.

Detecting the Cognitive Prodrome of Dementia with Lewy Bodies: A Prospective Study of REM Sleep Behavior Disorder

Study Objectives

Long-term studies in REM sleep behavior disorder (RBD) have shown a high rate of conversion into synucleinopathies. We aimed to prospectively follow-up a large cohort of RBD patients to identify cognitive markers for early detection of prodromal dementia.

Methods

Seventy-six idiopathic RBD patients underwent polysomnography and a complete neuropsychological and neurological assessment and were then followed for a mean of 3.6 years. Cognitive characteristics at baseline were compared between patients who remained disease-free and those who developed a synucleinopathy, and between those who developed dementia first and those who developed parkinsonism first. Receiver operating characteristic curves were calculated to assess the diagnostic value of cognitive tests for detecting prodromal dementia.

Results

At follow-up, 34 patients developed a neurodegenerative disease: 19 parkinsonism-first and 15 dementia-first. RBD patients who first developed dementia were impaired at baseline in all cognitive domains (attention/executive functions, learning/memory, and visuospatial) compared to patients who developed parkinsonism. Moreover, 93% of patients who first developed dementia had mild cognitive impairment at baseline compared to 42% of patients who developed parkinsonism. RBD patients who developed parkinsonism first were similar at baseline to disease-free RBD patients on cognition. In dementia-first patients, two cognitive tests assessing attention and executive functions (Stroop Color Word Test and Trail Making Test) reliably predicted dementia (area under the curve ≥0.85) compared to parkinsonism-first patients or controls.

Conclusions

This study shows that cognitive tests assessing attention and executive functions strongly predict conversion to dementia in RBD patients, and may be useful endpoints to determine the effectiveness of interventions to prevent cognitive deterioration in RBD patients.

[Diagnostic of prodromal dementia with Levy bodies]

The issues of diagnosis of prodromal dementia with Lewy bodies are considered. Despite numerous studies using international diagnostic criteria, clinical and diagnosis are often inconsistent. Early and more accurate detection of dementia with Lewy bodies is needed for prognosis, optimal management and effective pharmacotherapy.

Cognitive profile in prodromal dementia with Lewy bodies

Background

Cortical and subcortical cognitive impairments have been found in dementia with Lewy bodies (DLB). Roughly, they comprise visuoconstructive and executive dysfunction, whereas memory would remain relatively spared. However, the cognitive profile of patients with prodromal DLB remains poorly illustrated to date.

Methods

We included 37 patients with prodromal DLB (age 67.2 ± 8.6 years, 18 men, Mini Mental State Examination [MMSE] score 27.4 ± 2) and 29 healthy control subjects (HCs; age 68.8 ± 7.9 years, 15 men, MMSE score 29.0 ± 0.9). They were presented with an extensive neuropsychological test battery to assess memory; speed of processing; executive function; visuoperceptual, visuospatial and visuoconstructive abilities; language; and social cognition.

Results

Compared with HCs, patients had lower scores on a visual recognition memory test (Delayed Matching to Sample-48 items; p ≤ 0.021) and lower free recall (all p ≤ 0.035), but not total recall, performance on a verbal episodic memory test (Free and Cued Selective Reminding Test). Short-term memory (p = 0.042) and working memory (p = 0.002) scores were also lower in patients. Assessment of executive function showed no slowing but overall lower performance in patients than in HCs (all p ≤ 0.049), whereas assessment of instrumental function yielded mixed results. Indeed, patients had lower scores on language tests (p ≤ 0.022), apraxia for pantomime of tool use (p = 0.002) and imitation of meaningless gesture (p = 0.005), as well as weakened visuospatial abilities (p = 0.047). Visuoconstruction was also impaired in patients. However, visuoperceptual abilities did not differ between groups. Finally, theory of mind abilities were lower in patients than in HCs (p < 0.05), but their emotion recognition abilities were similar.

Conclusions

This study presents the cognitive profile in patients with prodromal DLB. In line with the literature on DLB with dementia, our results show lower performance on tests of executive function and visuoconstruction. However, we found, from a prodromal stage of DLB, memory (free recall and visual recognition) and social cognition deficits, as well as weakened visuospatial and praxic abilities.

Grey matter atrophy in prodromal stage of dementia with Lewy bodies and Alzheimer's disease

BACKGROUND

Little is known about the patterns of brain atrophy in prodromal dementia with Lewy bodies (pro-DLB).

METHODS

In this study, we used SPM8 with diffeomorphic anatomical registration through exponentiated lie algebra to measure grey matter (GM) volume and investigate patterns of GM atrophy in pro-DLB (n = 28) and prodromal Alzheimer's disease (pro-AD) (n = 27) and compared and contrasted them with those in elderly control subjects (n = 33) (P ≤ 0.05 corrected for family-wise error).

RESULTS

Patients with pro-DLB showed diminished GM volumes of bilateral insulae and right anterior cingulate cortex compared with control subjects. Comparison of GM volume between patients with pro-AD and control subjects showed a more extensive pattern, with volume reductions in temporal (hippocampi and superior and middle gyri), parietal and frontal structures in the former. Direct comparison of prodromal groups suggested that more atrophy was evident in the parietal lobes of patients with pro-AD than patients with pro-DLB. In patients with pro-DLB, we found that visual hallucinations were associated with relative atrophy of the left cuneus.

CONCLUSIONS

Atrophy in pro-DLB involves the insulae and anterior cingulate cortex, regions rich in von Economo neurons, which we speculate may contribute to the early clinical phenotype of pro-DLB.

Cognitive study on Chinese patients with idiopathic REM sleep behavior disorder

AIMS

We investigated cognitive abnormalities using standard tests in Chinese patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) compared with those in normal controls.

METHODS

Twenty-three patients with iRBD and 23 normal controls were included in this study. All of the participants underwent one night of video-polysomnography (PSG) monitoring to certify REM sleep without atonia or abnormal behaviors. The cognitive assessments were administered and scored according to a standard procedure, including global cognitive screening and attention/processing speed, executive function, memory, language, and visuospatial ability testing.

RESULTS

Patients with iRBD had similar scores of the Mini Mental State Examination (MMSE) but lower Montreal Cognitive Assessment (MoCA) scores compared with controls (p>0.05, p=0.013). The iRBD patients performed poorly on verbal memory tests, which included immediate recall (p<0.001), delayed recall (p<0.001), and false recognitions (p=0.002) of the Rey Auditory Verbal Learning Test (RAVLT). The visual memory and visuospatial abilities were also impaired in iRBD patients, as reflected by the copy (p=0.005) and immediate (p=0.004) and delayed (p=0.003) recall of the Rey-Osterrieth complex figure, although no difference was found after Bonferroni correction. The duration of RBD was 6.98±8.10years. After controlling for age, the duration of RBD was only correlated with the Trail Making Test B (r=0.613, p=0.045) and block design (r=-0.667, p=0.025).

CONCLUSIONS

Impaired verbal memory was observed in iRBD patients who identified as Chinese. MoCA could detect cognitive abnormalities and serve as a screening scale. The present study further confirmed cognitive deficits in iRBD as an early clinical marker in the prodromal stage of synucleinopathy.