A follow up study of non-demented patients with primary visual cortical hypometabolism: Prodromal dementia with Lewy bodies

Cerebral Glucose Metabolism Is a Valuable Predictor of Survival in Patients with Lewy Body Diseases

OBJECTIVE

Patients with Lewy body diseases have an increased risk of dementia, which is a significant predictor for survival. Posterior cortical hypometabolism on [18F]fluorodeoxyglucose positron emission tomography (PET) precedes the development of dementia by years. We therefore examined the prognostic value of cerebral glucose metabolism for survival.

METHODS

We enrolled patients diagnosed with Parkinson's disease (PD), Parkinson's disease with dementia, or dementia with Lewy bodies who underwent [18F]fluorodeoxyglucose PET. Regional cerebral metabolism of each patient was analyzed by determining the expression of the PD-related cognitive pattern (Z-score) and by visual PET rating. We analyzed the predictive value of PET for overall survival using Cox regression analyses (age- and sex-corrected) and calculated prognostic indices for the best model.

RESULTS

Glucose metabolism was a significant predictor of survival in 259 included patients (n = 118 events; hazard ratio: 1.4 [1.2-1.6] per Z-score; hazard ratio: 1.8 [1.5-2.2] per visual PET rating score; both p < 0.0001). Risk stratification with visual PET rating scores yielded a median survival of 4.8, 6.8, and 12.9 years for patients with severe, moderate, and mild posterior cortical hypometabolism (median survival not reached for normal cortical metabolism). Stratification into 5 groups based on the prognostic index revealed 10-year survival rates of 94.1%, 78.3%, 34.7%, 0.0%, and 0.0%.

INTERPRETATION

Regional cerebral glucose metabolism is a significant predictor of survival in Lewy body diseases and may allow an earlier survival prediction than the clinical milestone "dementia." Thus, [18F]fluorodeoxyglucose PET may improve the basis for therapy decisions, especially for invasive therapeutic procedures like deep brain stimulation in Parkinson's disease. ANN NEUROL 2024.

Differentiating Prodromal Dementia with Lewy Bodies from Prodromal Alzheimer's Disease: A Pragmatic Review for Clinicians

This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical presentations, neuropsychological profiles, neuropsychiatric symptoms, biomarkers, and indications for disease management. The core clinical features of dementia with Lewy bodies (DLB)-parkinsonism, complex visual hallucinations, cognitive fluctuations, and REM sleep behaviour disorder are common prodromal symptoms. Supportive clinical features of pDLB include severe neuroleptic sensitivity, as well as autonomic and neuropsychiatric symptoms. The neuropsychological profile in mild cognitive impairment attributable to Lewy body pathology (MCI-LB) tends to include impairment in visuospatial skills and executive functioning, distinguishing it from MCI due to AD, which typically presents with impairment in memory. pDLB may present with cognitive impairment, psychiatric symptoms, and/or recurrent episodes of delirium, indicating that it is not necessarily synonymous with MCI-LB. Imaging, fluid and other biomarkers may play a crucial role in differentiating pDLB from pAD. The current MCI-LB criteria recognise low dopamine transporter uptake using positron emission tomography or single photon emission computed tomography (SPECT), loss of REM atonia on polysomnography, and sympathetic cardiac denervation using meta-iodobenzylguanidine SPECT as indicative biomarkers with slowing of dominant frequency on EEG among others as supportive biomarkers. This review also highlights the emergence of fluid and skin-based biomarkers. There is little research evidence for the treatment of pDLB, but pharmacological and non-pharmacological treatments for DLB may be discussed with patients. Non-pharmacological interventions such as diet, exercise, and cognitive stimulation may provide benefit, while evaluation and management of contributing factors like medications and sleep disturbances are vital. There is a need to expand research across diverse patient populations to address existing disparities in clinical trial participation. In conclusion, an early and accurate diagnosis of pDLB or pAD presents an opportunity for tailored interventions, improved healthcare outcomes, and enhanced quality of life for patients and care partners.

The functional brain connectome in isolated rapid eye movement sleep behavior disorder and Parkinson's disease

BACKGROUND

Isolated rapid-eye-movement behavior disorder (iRBD) often precedes the development of alpha-synucleinopathies such as Parkinson's disease (PD). Magnetic resonance imaging (MRI) studies have revealed structural brain alterations in iRBD partially resembling those observed in PD. However, relatively little is known about whole-brain functional brain alterations in iRBD. Here, we characterize the functional brain connectome of iRBD compared with PD patients and healthy controls (HC) using resting-state functional MRI (rs-fMRI).

METHODS

Eighteen iRBD subjects (67.3 ± 6.6 years), 18 subjects with PD (65.4 ± 5.8 years), and 39 age- and sex-matched HC (64.4 ± 9.2 years) underwent rs-fMRI at 3 T. We applied a graph theoretical approach to analyze the brain functional connectome at the global and regional levels. Data were analyzed using both frequentist and Bayesian statistics.

RESULTS

Global connectivity was largely preserved in iRBD and PD individuals. In contrast, both disease groups displayed altered local connectivity mainly in the motor network, temporal cortical regions including the limbic system, and the visual system. There were some group specific alterations, and connectivity changes were pronounced in PD individuals. Overall, however, there was a good agreement of the connectome changes observed in both disease groups.

CONCLUSIONS

This study provides evidence for widespread functional brain connectivity alterations in iRBD, including motor circuitry, despite normal motor function. Connectome alterations showed substantial resemblance with those observed in PD, underlining a close pathophysiological relationship of iRBD and PD.

Brain 18 F-FDG-PET and an optimized cingulate island ratio to differentiate Lewy body dementia and Alzheimer's disease

BACKGROUND AND PURPOSE

The diagnosis of Dementia with Lewy Bodies (DLB) is challenging due to various clinical presentations and clinical and neuropathological features that overlap with Alzheimer's disease (AD). The use of ¹⁸ F-Fluorodeoxyglucose-PET (¹⁸ F-FDG-PET) can be limited due to similar patterns in DLB and AD. However, metabolism in the posterior cingulate cortex is known to be relatively preserved in DLB and visual assessment of the "cingulate island sign" became a helpful tool in the analysis of 18F-FDG-PET. The aim of this study was the evaluation of visual and semiquantitative 18F-FDG-PET analyses in the diagnosis of DLB and the differentiation to AD as well as its relation to other dementia biomarkers.

METHODS

This retrospective study comprises 81 patients with a clinical diagnosis of DLB or AD that underwent ¹⁸ F-FDG-PET/CT. PET scans were analyzed visually and semiquantitatively and results were compared to clinical data, cerebrospinal fluid results, dopamine transporter scintigraphy, and 18F-Florbetaben-PET. Furthermore, different cingulate island ratios were calculated to analyze their diagnostic accuracy.

RESULTS

Visual assessment of 18F-FDG-PET showed an accuracy of 62%-77% in differentiating between DLB and AD. Standard uptake values were significantly lower in the primary visual cortex and the lateral occipital cortex of DLB patients compared to AD patients. The cingulate island ratio was significantly higher in the DLB group compared to the AD group and the ratio posterior cingulate cortex to visual cortex plus lateral occipital cortex showed the highest diagnostic accuracy to discriminate between DLB and AD at 81%.

CONCLUSIONS

Semiquantitative 18F-FDG-PET imaging and especially the use of an optimized cingulate island ratio are valuable tools to differentiate between DLB and AD.

Imaging of sleep disorders in pre-Parkinsonian syndromes

PURPOSE OF REVIEW

Neuroimaging has been advanced in the last years and enabled clinicians to evaluate sleep disorders, especially isolated rapid eye movement sleep disorder (iRBD), which can be seen in alpha-synucleinopathies. iRBD is the best prodromal clinical marker for phenoconversion to these neurodegenerative diseases. This review aims to provide an update on advanced neuroimaging biomarkers in iRBD.

RECENT FINDINGS

Advanced structural MRI techniques, such as diffusion tensor imaging and functional MRI, neuromelanin-sensitive MRI, and scintigraphic neuroimaging such as cholinergic PET, dopamine transporter imaging - single-photon emission computerized tomography, perfusional single-photon emission computerized tomography, and cardiac metaiodobenzylguanidine can provide diagnostic and prognostic imaging biomarkers for iRBD, in isolation and more robustly when combined.

SUMMARY

New advanced neuroimaging can provide imaging biomarkers and aid in the appropriate clinical assessment and future therapeutic trials.

Resting-State Functional Network Topology Alterations of the Occipital Lobe Associated With Attention Impairment in Isolated Rapid Eye Movement Behavior Disorder

Purpose

This study investigates the topological properties of brain functional networks in patients with isolated rapid eye movement sleep behavior disorder (iRBD).

Participants and Methods

A total of 21 patients with iRBD (iRBD group) and 22 healthy controls (HCs) were evaluated using resting-state functional MRI (rs-fMRI) and neuropsychological measures in cognitive and motor function. Data from rs-fMRI were analyzed using graph theory, which included small-world properties, network efficiency, network local efficiency, nodal shortest path, node efficiency, and network connectivity, as well as the relationship between behavioral characteristics and altered brain topological features.

Results

Rey-Osterrieth complex figure test (ROCFT-copy), symbol digital modalities test (SDMT), auditory verbal learning test (AVLT)-N1, AVLT-N2, AVLT-N3, and AVLT-N1-3 scores were significantly lower in patients with iRBD than in HC (P &lt; 0.05), while trail making test A (TMT-A), TMT-B, and Unified Parkinson’s Disease Rating Scale Part-III (UPDRS-III) scores were higher in patients with iRBD (P &lt; 0.05). Compared with the HCs, patients with iRBD had no difference in the small-world attributes (P &gt; 0.05). However, there was a significant decrease in network global efficiency (P = 0.0052) and network local efficiency (P = 0.0146), while an increase in characteristic path length (P = 0.0071). There was lower nodal efficiency in occipital gyrus and nodal shortest path in frontal, parietal, temporal lobe, and cingulate gyrus. Functional connectivities were decreased between the nodes of occipital with the regions where they had declined nodal shortest path. There was a positive correlation between TMT-A scores and the nodal efficiency of the right middle occipital gyrus (R = 0.602, P = 0.014).

Conclusion

These results suggest that abnormal behaviors may be associated with disrupted brain network topology and functional connectivity in patients with iRBD and also provide novel insights to understand pathophysiological mechanisms in iRBD.

Commercial and Instant Coffees Effectively Lower Aβ1-40 and Aβ1-42 in N2a/APPswe Cells

Background

Alzheimer's disease (AD) is a multifactorial neurological disease with neurofibrillary tangles and neuritic plaques as histopathological markers. Due to this, although AD is the leading cause of dementia worldwide, clinical AD dementia cannot be certainly diagnosed until neuropathological post-mortem evaluation. Coffee has been reported to have neurologically protective factors, particularly against AD, but coffee brand and type have not been taken into consideration in previous studies. We examined the discrepancies among popular commercial and instant coffees in limiting the development and progression through Aβ1-40 and Aβ1-42 production, and hypothesized that coffee consumption, regardless of brand or type, is beneficial for stalling the progression and development of Aβ-related AD.

Methods

Coffee samples from four commercial coffee brands and four instant coffees were purchased or prepared following given instructions and filtered for the study. 5, 2.5, and 1.25% concentrations of each coffee were used to treat N2a/APPswe cell lines. MTT assay was used to assess cell viability for coffee concentrations, as well as pure caffeine concentrations. Sandwich ELISA assay was used to determine Aβ concentration for Aβ1-40 and Aβ1-42 peptides of coffee-treated cells.

Results

Caffeine concentrations were significantly varied among all coffees (DC vs. MDC, PC, SB, NIN, MIN p < 0.05). There was no correlation between caffeine concentration and cell toxicity among brands and types of coffee, with no toxicity at 0.5 mg/ml caffeine and lower. Most coffees were toxic to N2a/APPswe cells at 5% (p < 0.05), but not at 2.5%. Most coffees at a 2.5% concentration reduced Aβ1-40 and Aβ1-42 production, with comparable results between commercial and instant coffees.

Conclusion

All coffees tested have beneficial health effects for AD through lowering Aβ1-40 and Aβ1-42 production, with Dunkin' Donuts® medium roast coffee demonstrating the most consistent and optimal cell survival rates and Aβ concentration. On the other hand, Starbucks® coffee exhibited the highest cell toxicity rates among the tested coffees.

Circuit imaging biomarkers in preclinical and prodromal Parkinson's disease

Parkinson's disease (PD) commences several years before the onset of motor features. Pathophysiological understanding of the pre-clinical or early prodromal stages of PD are essential for the development of new therapeutic strategies. Two categories of patients are ideal to study the early disease stages. Idiopathic rapid eye movement sleep behavior disorder (iRBD) represents a well-known prodromal stage of PD in which pathology is presumed to have reached the lower brainstem. The majority of patients with iRBD will develop manifest PD within years to decades. Another category encompasses non-manifest mutation carriers, i.e. subjects without symptoms, but with a known mutation or genetic variant which gives an increased risk of developing PD. The speed of progression from preclinical or prodromal to full clinical stages varies among patients and cannot be reliably predicted on the individual level. Clinical trials will require inclusion of patients with a predictable conversion within a limited time window. Biomarkers are necessary that can confirm pre-motor PD status and can provide information regarding lead time and speed of progression. Neuroimaging changes occur early in the disease process and may provide such a biomarker. Studies have focused on radiotracer imaging of the dopaminergic nigrostriatal system, which can be assessed with dopamine transporter (DAT) single photon emission computed tomography (SPECT). Loss of DAT binding represents an effect of irreversible structural damage to the nigrostriatal system. This marker can be used to monitor disease progression and identify individuals at specific risk for phenoconversion. However, it is known that changes in neuronal activity precede structural changes. Functional neuro-imaging techniques, such as ¹⁸F-2-fluoro-2-deoxy-D-glucose Positron Emission Tomography (¹⁸F-FDG PET) and functional magnetic resonance imaging (fMRI), can be used to model the effects of disease on brain networks when combined with advanced analytical methods. Because these changes occur early in the disease process, functional imaging studies are of particular interest in prodromal PD diagnosis. In addition, fMRI and ¹⁸F-FDG PET may be able to predict a specific future phenotype in prodromal cohorts, which is not possible with DAT SPECT. The goal of the current review is to discuss the network-level brain changes in pre-motor PD.

Early diagnosis of prodromal dementia with Lewy bodies using clinical history of probable REM sleep behaviour disorder and cardiac 123 I-MIBG scintigraphy in memory clinics

BACKGROUND

Rapid eye movement sleep behaviour disorder (RBD) is associated with reduced cardiac ¹²³ I-metaiodobenzylguanidine (MIBG) uptake and often precedes the onset of Lewy body (LB) disorders. We investigated the role of cardiac ¹²³ I-MIBG scintigraphy in relation to probable RBD for the clinical diagnosis of prodromal dementia with Lewy bodies (DLB) in memory clinics.

METHODS

We reviewed clinical profiles of 60 consecutive patients who underwent cardiac ¹²³ I-MIBG scintigraphy in our memory clinics. The diagnostic threshold of 2.20 was used as the cut-off for the heart-to-mediastinum ratio at the delayed phase.

RESULTS

Cardiac ¹²³ I-MIBG abnormality was identified in 28 patients at baseline; six were cognitively unimpaired, six had mild cognitive impairment (MCI)-LB, and 16 had probable DLB based on the National Institute on Aging and Alzheimer's Association Research Framework. Although the number of core features increased in accordance with the progression of three cognitive categories, there were no differences in the prevalence of probable RBD and the cardiac MIBG scintigraphy indices among them. During the observation period, two cognitively unimpaired patients with probable RBD progressed to MCI-LB, and three MCI-LB patients with probable RBD developed DLB. The prevalence of final diagnosis of probable MCI-LB or DLB was significantly higher in these patients (85%) than the remaining 32 patients without (9%). Of 25 patients with probable RBD, 22 (88%) had a cardiac ¹²³ I-MIBG abnormality regardless of cognitive conditions. Only one patient consulted a sleep centre for the abnormal sleep behaviour before visiting our memory clinics. Regarding the gender differences, male predominance was not identified and sleep-related injury more frequently occurred in men (7/12, 58%) than in women (1/10, 10%).

CONCLUSIONS

Proactive detection of probable RBD plus cardiac ¹²³ I-MIBG abnormality provides the opportunity for an early diagnosis of prodromal DLB in memory clinics. This approach warrants further follow-up studies with polysomnographic and pathological verification.

Cognitive Decline in Mild Cognitive Impairment With Lewy Bodies or Alzheimer Disease: A Prospective Cohort Study

OBJECTIVE

We explored whether the mild cognitive impairment (MCI) stages of dementia with Lewy bodies (DLB) and Alzheimer disease (AD) differ in their cognitive profiles, and longitudinal progression.

DESIGN

A prospective, longitudinal design was utilized with annual follow-up (Max 5 years, Mean 1.9, standard deviation 1.1) after diagnosis. Participants underwent repeated cognitive testing, and review of their clinical diagnosis and symptoms, including evaluation of core features of DLB.

SETTING

This was an observational study of independently living individuals, recruited from local healthcare trusts in North East England, UK.

PARTICIPANTS

An MCI cohort (n = 76) aged ≥60 years was utilized, differentially diagnosed with MCI due to AD (MCI-AD), or possible/probable MCI with Lewy bodies (MCI-LB).

MEASUREMENTS

A comprehensive clinical and neuropsychological testing battery was administered, including ACE-R, trailmaking tests, FAS verbal fluency, and computerized battery of attention and perception tasks.

RESULTS

Probable MCI-LB presented with less impaired recognition memory than MCI-AD, greater initial impairments in verbal fluency and perception of line orientation, and thereafter demonstrated an expedited decline in visuo-constructional functions in the ACE-R compared to MCI-AD. No clear diagnostic group differences were found in deterioration speeds for global cognition, language, overall memory, attention or other executive functions.

CONCLUSION

These findings provide further evidence for differences in severity and decline of visuospatial dysfunctions in DLB compared with AD; further exploration is required to clarify when and how differences in attention, executive, and memory functions emerge, as well as speed of decline to dementia.

Parkinson Disease-Related Pattern of Glucose Metabolism Associated With the Potential for Motor Improvement After Deep Brain Stimulation

BACKGROUND

Motor dysfunctions in Parkinson disease (PD) patients are not completely normalized by deep brain stimulation (DBS), and there is an obvious difference in the degree of symptom improvement after DBS for each patient.

OBJECTIVE

To test our hypothesis that each patient has their own restoration capacity for motor improvement after DBS, and to investigate whether regional cerebral glucose metabolism in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scans is associated with the capacity for off-medication motor improvement (MIoff) after DBS.

METHODS

The MIoff (%) was calculated using the Unified Parkinson's Disease Rating Scale part III in 27 PD patients undergoing DBS in the globus pallidus interna. The standardized uptake value ratios (SUVRs) on FDG-PET were quantitatively measured, and the areas where the SUVR correlated with the MIoff (%) were identified. Also, the areas where the SUVR was significantly different between the 2 MIoff groups (≥60% vs <60%) were determined.

RESULTS

Ten patients achieved MIoff > 60% at 12 mo after DBS. In general, the MIoff (%) was positively correlated with preoperative SUVR in the temporo-parieto-occipital lobes, while it was inversely correlated with the metabolism in the primary motor cortex. The patients in the MIoff < 60% group showed a significant decrease in SUVR in the parieto-occipital lobes, while parieto-occipital metabolism in those with MIoff ≥ 60% was relatively preserved (Mann-Whitney U test, P = .03).

CONCLUSION

Our findings suggest that the parieto-occipital lobes may be implicated more generally in the prognosis of motor improvement after DBS in advanced PD than other regions.

[Changes of brain structural network properties in patients with rapid eye movement sleep behavior disorder]

OBJECTIVE

To investigate the changes in behaviors and brain structural network in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD).

METHODS

Twenty patients with iRBD (iRBD group) and 22 healthy control subjects were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn-Yahr staging. Diffusion tensor imaging and graph- theoretical analysis were performed for analyzing the topological characteristics of brain structural networks of the patients, and the correlation between the behavioral changes and the changes in the topological characteristics of the brain networks was analyzed.

RESULTS

The UPDRS score was significantly higher in iRBD group than in the healthy control group (P < 0.05). No significant difference was found in small-world attributes between the patients with iRBD and the control subjects (P>0.05). The patients with iRBD exhibited significantly shortened characteristic shortest path length Lp (P < 0.05) and significantly increased global efficiency, local efficiency and assortativity (P < 0.05). Examination of regional topological properties of the brain network revealed abnormal node properties in the frontal, temporal, parietal, occipital, and striatal and limbic lobes in patients with iRBD. The patients also had significantly increased degree centrality of the left pallidum and enhanced nodal efficiency in the left thalamus, superior temporal gyrus, temporal pole and bilateral superior occipital gyrus, bilateral putamens as well as the right gyrus rectus, amygdala, supramarginal gyrus, and middle temporal gyrus. The nodal local efficiency was significantly increased in the left superior frontal gyrus, middle cingulate gyrus, superior parietal gyrus, bilateral fusiform gyrus, right superior motor area, postcentral gyrus and angular gyrus of the patients with iRBD. The nodal shortest path was significantly shortened in the left superior motor area, pallidum, thalamus, superior temporal gyrus, temporal pole, bilateral putamens, bilateral superior occipital gyrus, right rectus gyrus, amygdala, supramarginal gyrus and middle temporal gyrus, and the nodal clustering coefficient was significantly lowered in the left superior occipital gyrus of the patients. In patients with iRBD, the UPDRS I score was positively correlated with the nodal efficiency in the right supramarginal gyrus (r=0.50, P < 0.05) and local nodal efficiency in the right fusiform gyrus (r=0.53, P < 0.05), and negatively correlated with the nodal clustering coefficient in the left superior occipital gyrus (r=-0.552, P < 0.05).

CONCLUSIONS

Patients with iRBD present with abnormal changes in mental condition, behaviors, emotions, activities of daily living and motor functions. The brain structural network of patient with iRBD still has a small-world property with abnormal global topological property and abnormal distribution of local topological property in the cortex, striatum and limbic system.

Correlations of Neuropsychological and Metabolic Brain Changes in Parkinson's Disease and Other α-Synucleinopathies

Cognitive impairment is a common feature in Parkinson's disease (PD) and other α-synucleinopathies as 80% of PD patients develop dementia within 20 years. Early cognitive changes in PD patients present as a dysexecutive syndrome, broadly characterized as a disruption of the fronto-striatal dopamine network. Cognitive deficits in other domains (recognition memory, attention processes and visuospatial abilities) become apparent with the progression of PD and development of dementia. In dementia with Lewy bodies (DLB) the cognitive impairment develops early or even precedes parkinsonism and it is more pronounced in visuospatial skills and memory. Cognitive impairment in the rarer α-synucleinopathies (multiple system atrophy and pure autonomic failure) is less well studied. Metabolic brain imaging with positron emission tomography and [¹⁸F]-fluorodeoxyglucose (FDG-PET) is a well-established diagnostic method in neurodegenerative diseases, including dementias. Changes in glucose metabolism precede those seen on structural magnetic resonance imaging (MRI). Reduction in glucose metabolism and atrophy have been suggested to represent consecutive changes of neurodegeneration and are linked to specific cognitive disorders (e.g., dysexecutive syndrome, memory impairment, visuospatial deficits etc.). Advances in the statistical analysis of FDG-PET images enabling a network analysis broadened our understanding of neurodegenerative brain processes. A specific cognitive pattern related to PD was identified by applying voxel-based network modeling approach. The magnitude of this pattern correlated significantly with patients' cognitive skills. Specific metabolic brain changes were observed also in patients with DLB as well as in a prodromal phase of α-synucleinopathy: REM sleep behavior disorder. Metabolic brain imaging with FDG-PET is a reliable biomarker of neurodegenerative brain diseases throughout their course, precisely reflecting their topographic distribution, stage and functional impact.

Imaging in prodromal dementia with Lewy bodies: Where do we stand?

OBJECTIVES

The aim of this review was to provide an overview of the literature on imaging in prodromal dementia with Lewy bodies (DLB).

DESIGN

Systematic PubMed search and literature review.

RESULTS

Diagnostic classification of the prodromal DLB stage remains to be established but is likely to require imaging biomarkers to improve diagnostic accuracy. In subjects with mild cognitive impairment with Lewy body disease (MCI-LB) (here synonymous with prodromal DLB) and REM sleep behaviour disorder, a high risk condition for future conversion to a synucleinopathy, imaging modalities have assessed early structural brain changes, striatal dopaminergic integrity, metabolic brain, and cerebral perfusion alterations. It remains uncertain whether structural brain imaging can differentiate MCI-LB from mild cognitive impairment with Alzheimer disease (MCI-AD), but early right anterior insula thinning has been reported to occur in MCI-LB compared with MCI-AD. Dopaminergic deficits have been observed in a substantial proportion of MCI-LB subjects and have a high specificity for Lewy body disease at the pre-dementia stage. Cardiac sympathetic denervation, occipital hypometabolism, or hypoperfusion is less studied as this pre-dementia stage and it remains to be determined whether any imaging abnormalities antedate DLB.

CONCLUSION

Imaging studies in prodromal DLB are still in their infancy but offer great potential to study early in vivo structural and functional biological alterations. Future work should focus on longitudinal multimodal imaging studies with postmortem validation of diagnosis in order to develop and then validate criteria for prodromal DLB.

Behavioral symptomatology and psychopharmacology of Lewy body dementia

Lewy body dementia (LBD) is an umbrella term for major neurocognitive disorders caused by Lewy body pathology. Parkinson's disease dementia (PDD) and Dementia with Lewy bodies (DLB) are the two main syndromes in LBD. LBDs typically present with cognitive impairment, cholinergic deficiency, neuropsychiatric symptoms such as visual hallucinations and paranoid delusions, as well as parkinsonian symptoms. Due to the urgency in diagnosing LBD early in the disease course to provide the most optimal management of these syndromes, it is important that clinicians elicit the most clinically significant symptoms during patient encounters. The focus of this chapter is to discuss current LBD classification systems and assessments, neuropathology of LBDs, behavioral symptomatology, contemporary management options, and possible future targets of treatment. PubMed was searched to obtain reviews and studies that pertain to classification, behavioral symptomatology, neurobiology, neuroimaging, and treatment of LBDs. Articles were chosen with a predilection to more recent clinical trials and systematic reviews or meta-analyses. Updates to diagnostic criteria have increased clinical diagnostic sensitivity and specificity. Current therapeutic modalities are limited as there is no current disease-modifying drug available. Cholinesterase inhibitors have been reported to be effective in decreasing neuropsychiatric and cognitive symptoms. Neuroleptics should be avoided unless clinically indicated. There is a paucity of studies investigating treatment options for mood symptoms. Current novel targets of treatment focus on decreasing α-synuclein burden. LBDs are a group of dementia syndromes that affect a significant portion of the elderly population. Early diagnosis and treatment is necessary to improve patient quality of life with current treatment options more focused on alleviating severe symptomatology rather than modifying disease pathology.

COGEVIS: A New Scale to Evaluate Cognition in Patients with Visual Deficiency

We evaluated the cognitive status of visually impaired patients referred to low vision rehabilitation (LVR) based on a standard cognitive battery and a new evaluation tool, named the COGEVIS, which can be used to assess patients with severe visual deficits. We studied patients aged 60 and above, referred to the LVR Hospital in Paris. Neurological and cognitive evaluations were performed in an expert memory center. Thirty-eight individuals, 17 women and 21 men with a mean age of 70.3 ± 1.3 years and a mean visual acuity of 0.12 ± 0.02, were recruited over a one-year period. Sixty-three percent of participants had normal cognitive status. Cognitive impairment was diagnosed in 37.5% of participants. The COGEVIS score cutoff point to screen for cognitive impairment was 24 (maximum score of 30) with a sensitivity of 66.7% and a specificity of 95%. Evaluation following 4 months of visual rehabilitation showed an improvement of Instrumental Activities of Daily Living (p = 0.004), National Eye Institute Visual Functioning Questionnaire (p = 0.035), and Montgomery–Åsberg Depression Rating Scale (p = 0.037). This study introduces a new short test to screen for cognitive impairment in visually impaired patients.

Early diagnosis of Lewy body disease in patients with late-onset psychiatric disorders using clinical history of rapid eye movement sleep behavior disorder and [123 I]-metaiodobenzylguanidine cardiac scintigraphy

AIM

Rapid eye movement sleep behavior disorder (RBD) and psychiatric symptoms often antedate the clinical diagnosis of Parkinson's disease or dementia with Lewy bodies. The purpose of this study was to investigate RBD and its relevance to Lewy body disease (LBD) in patients with late-onset psychiatric disorders.

METHODS

Study subjects included 19 patients with late-onset psychiatric disorders who exhibited REM sleep without atonia (RWA), which is a hallmark of RBD on polysomnography, at our psychiatric ward. Clinical profiles and radiological findings by cardiac [¹²³ I]-metaiodobenzylguanidine ([¹²³ I]-MIBG) scintigraphy and imaging for the dopamine transporter (DAT) were compared between patients with and without RBD symptoms. The correlations between the percentage of RWA in the total rapid eye movement sleep (%RWA) and radiological findings were also investigated.

RESULTS

Nine patients reported RBD symptoms only on specific questioning, but clinical profiles, including the prevalence of antipsychotropic usage, did not differ when compared to the remaining 10 patients without RBD (incidental RWA group). The median %RWA was significantly higher in the definite RBD group than in the incidental RWA group. Although the cardiac [¹²³ I]-MIBG uptake was significantly lower in the definite RBD group than in the incidental RWA group, there was overlap in the specific binding ratio on DAT scan.

CONCLUSION

The severity of %RWA was highly correlated with the value of cardiac [¹²³ I]-MIBG uptake, but not with specific binding ratio on DAT scan. Clinical history of RBD and cardiac [¹²³ I]-MIBG scintigraphy are helpful for an early differential diagnosis of LBD from late-onset psychiatric disorders, even before parkinsonism or dementia appears.

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.

FDG-PET and CSF biomarker accuracy in prediction of conversion to different dementias in a large multicentre MCI cohort

Background/aims

In this multicentre study in clinical settings, we assessed the accuracy of optimized procedures for FDG-PET brain metabolism and CSF classifications in predicting or excluding the conversion to Alzheimer's disease (AD) dementia and non-AD dementias.

Methods

We included 80 MCI subjects with neurological and neuropsychological assessments, FDG-PET scan and CSF measures at entry, all with clinical follow-up. FDG-PET data were analysed with a validated voxel-based SPM method. Resulting single-subject SPM maps were classified by five imaging experts according to the disease-specific patterns, as "typical-AD", "atypical-AD" (i.e. posterior cortical atrophy, asymmetric logopenic AD variant, frontal-AD variant), "non-AD" (i.e. behavioural variant FTD, corticobasal degeneration, semantic variant FTD; dementia with Lewy bodies) or "negative" patterns. To perform the statistical analyses, the individual patterns were grouped either as "AD dementia vs. non-AD dementia (all diseases)" or as "FTD vs. non-FTD (all diseases)". Aβ42, total and phosphorylated Tau CSF-levels were classified dichotomously, and using the Erlangen Score algorithm. Multivariate logistic models tested the prognostic accuracy of FDG-PET-SPM and CSF dichotomous classifications. Accuracy of Erlangen score and Erlangen Score aided by FDG-PET SPM classification was evaluated.

Results

The multivariate logistic model identified FDG-PET "AD" SPM classification (Expβ = 19.35, 95% C.I. 4.8-77.8, p < 0.001) and CSF Aβ42 (Expβ = 6.5, 95% C.I. 1.64-25.43, p < 0.05) as the best predictors of conversion from MCI to AD dementia. The "FTD" SPM pattern significantly predicted conversion to FTD dementias at follow-up (Expβ = 14, 95% C.I. 3.1-63, p < 0.001). Overall, FDG-PET-SPM classification was the most accurate biomarker, able to correctly differentiate either the MCI subjects who converted to AD or FTD dementias, and those who remained stable or reverted to normal cognition (Expβ = 17.9, 95% C.I. 4.55-70.46, p < 0.001).

Conclusions

Our results support the relevant role of FDG-PET-SPM classification in predicting progression to different dementia conditions in prodromal MCI phase, and in the exclusion of progression, outperforming CSF biomarkers.

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.

REM sleep without atonia in middle-aged and older psychiatric patients and Lewy body disease: a case series

OBJECTIVE

Rapid eye movement (REM) sleep behavior disorder (RBD) is commonly associated with Lewy body disease, narcolepsy, or depression. In contrast, the relationship between REM sleep without atonia (RWA), which is a hallmark of RBD on polysomnography, and clinical characteristics remains unclear. The purpose of this study is to investigate the clinical features of psychiatric patients exhibiting RWA and its relevance to Lewy body disease.

METHODS

Of 55 consecutive patients who underwent polysomnography at the psychiatric ward, 25 patients with sleep apnea syndrome were excluded, and 12 patients exhibiting RWA were identified. The clinical profiles were compared between the groups with and without RWA.

RESULTS

The mean age and the frequency of neurocognitive disorders were significantly higher in 12 patients with RWA than in 18 without. Only five of the 12 patients exhibiting RWA had episodes of dream-enactment behavior, and fulfilled the clinical criteria for RBD. Two young patients were diagnosed with narcolepsy, while the other middle-aged and older patients fulfilled the clinical criteria for Parkinson's disease (n = 1), dementia with Lewy bodies (n = 4), idiopathic RBD (n = 2), and major depressive disorder (MDD) (n = 3). The patients with MDD exhibited constipation and/or olfactory dysfunction. Moreover, neuroimaging examinations in the patients with MDD revealed isolated occipital hypoperfusion in three patients and mild dopamine transporter deficit in one patient.

CONCLUSIONS

Rapid eye movement sleep without atonia itself may be associated with specific clinical profiles, even when dream-enactment behavior is absent. Continued follow-up of the patients with MDD exhibiting RWA is warranted to determine if they represent the prodromal Parkinson's disease/dementia with Lewy bodies. Copyright © 2016 John Wiley & Sons, Ltd.

Magnetic resonance imaging and positron emission tomography in the diagnosis of neurodegenerative dementias

Neuroimaging, both with magnetic resonance imaging (MRI) and positron emission tomography (PET), has gained a pivotal role in the diagnosis of primary neurodegenerative diseases. These two techniques are used as biomarkers of both pathology and progression of Alzheimer's disease (AD) and to differentiate AD from other neurodegenerative diseases. MRI is able to identify structural changes including patterns of atrophy characterizing neurodegenerative diseases, and to distinguish these from other causes of cognitive impairment, e.g. infarcts, space-occupying lesions and hydrocephalus. PET is widely used to identify regional patterns of glucose utilization, since distinct patterns of distribution of cerebral glucose metabolism are related to different subtypes of neurodegenerative dementia. The use of PET in mild cognitive impairment, though controversial, is deemed helpful for predicting conversion to dementia and the dementia clinical subtype. Recently, new radiopharmaceuticals for the in vivo imaging of amyloid burden have been licensed and more tracers are being developed for the assessment of tauopathies and inflammatory processes, which may underlie the onset of the amyloid cascade. At present, the cerebral amyloid burden, imaged with PET, may help to exclude the presence of AD as well as forecast its possible onset. Finally PET imaging may be particularly useful in ongoing clinical trials for the development of dementia treatments. In the near future, the use of the above methods, in accordance with specific guidelines, along with the use of effective treatments will likely lead to more timely and successful treatment of neurodegenerative dementias.

Characteristics of mild cognitive impairment tending to convert into Alzheimer's disease or dementia with Lewy bodies: A follow-up study in a memory clinic

AIM

To determine characteristics of MCI that can predict whether patients will go on to develop AD or DLB.

METHODS

Ninety-three patients diagnosed with MCI underwent neuropsychological and neuroimaging examinations, and were followed-up for a mean of 44.9±19.3months. They were divided into four MCI subtypes (amnestic/non-amnestic MCI, single/multiple domain) according to neuropsychological findings, and into three other MCI categories (AD-type PET, DLB-type PET, and unknown-type PET) based on (18)F-fluorodeoxyglucose PET findings. Patients who were eventually diagnosed with AD, DLB, other dementia, or remained MCI were analyzed in relation to the groups to which they had initially been allocated at the MCI stage.

RESULTS

Clinical diagnosis after follow-up determined AD in 21 patients (22.6%), DLB in 12 patients (12.9%), other dementia in 2 patients (2.2%), and non-converter in 58 patients (62.3%). Amnestic single-domain MCI and AD-type PET tended to convert into AD. Amnestic multiple-domain MCI and DLB-type PET tended to convert into DLB. A few patients with AD-type PET later developed DLB, and some with DLB-type PET later developed AD.

CONCLUSIONS

Predicting which type of dementia a person with MCI will later develop might be possible based on early assessment with clinical symptoms in conjunction with neuropsychological and (18)F-fluorodeoxyglucose PET findings.

123I-FP-CIT SPECT findings and its clinical relevance in prodromal dementia with Lewy bodies

PURPOSE

Evidence for the prodromal stage of dementia with Lewy bodies (DLB) is very limited. To address this issue, we investigate the ¹²³I-FP-CIT SPECT measure of dopamine transporter binding finding and its clinical relevance.

METHODS

We enrolled subjects into a prodromal DLB group (PRD-DLB) (n = 20) and clinical DLB group (CLIN-DLB) (n = 18) and compared these groups with an Alzheimer's disease control group (AD) (n = 10). PRD-DLB was defined as patients having the non-motor symptoms associated with Lewy body disease (LBD) [i.e. REM sleep behavior disorder (RBD), olfactory dysfunction, autonomic dysfunction, and depression] and showing characteristic diffuse occipital hypometabolism in ¹⁸F-FDG PET. CLIN-DLB was defined as patients fulfilling the established criteria of probable DLB. Striatal specific binding ratio (SBR) of ¹²³I-FP-CIT SPECT was used for objective group comparisons. The correlations between SBR and cognitive function (MMSE), motor symptoms (UPDRS3), and duration of LBD-associated non-motor symptoms were compared between the two DLB groups.

RESULTS

Mean SBR scores of both PRD-DLB and CLIN-DLB were significantly lower than those of AD. No correlation was found between SBR and MMSE scores. Both in the CLIN-DLB and total DLB groups, SBR scores were negatively correlated with UPDRS3 scores, whereas no correlation was found in PRD-DLB. Among the LBD-related non-motor symptoms, duration of olfactory dysfunction, and RBD demonstrated negative correlation with SBR scores in PRD-DLB.

CONCLUSION

¹²³I-FP-CIT SPECT may play a role for detecting DLB among the subjects in prodromal stage. During this stage, long-term olfactory dysfunction and/or RBD may indicate more severe degeneration of the nigro-striatal dopaminergic pathway.

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.

Early differential diagnosis between Alzheimer's disease and dementia with Lewy bodies: Comparison between (18)F-FDG PET and (123)I-IMP SPECT

Both (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and (123)I-iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) have been used for the differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Less information is available, however, regarding the differential diagnosis of mild cognitive impairment (MCI) due to AD and MCI due to DLB. We examined nine AD patients (AD group), nine DLB patients (DLB group), eight MCI due to AD patients (MCI-AD group), and nine MCI due to DLB patients (MCI-DLB group) with FDG PET and IMP SPECT using a well-characterized normal database and a stereotactic extraction estimation method. In the AD and DLB groups, receiver operating characteristic (ROC) analysis in the occipital regions showed significant accuracy of both FDG PET and IMP SPECT for the differential diagnosis. In the MCI-AD and MCI-DLB groups, ROC analysis showed significant accuracy of only FDG PET for the differential diagnosis. Both FDG PET and IMP SPECT would be useful for the differential diagnosis between AD and DLB. For the differential diagnosis of MCI-AD versus MCI-DLB, FDG PET would be more useful than IMP SPECT.

Prediction of later clinical course by a specific glucose metabolic pattern in non-demented patients with probable REM sleep behavior disorder admitted to a memory clinic: A case study

The present study is a follow-up study of 11 non-demented patients with probable rapid eye movement (REM) sleep behavior disorder (RBD) at our memory clinic. During the follow-up period (mean±SD of 46.7±6.4 months), all 11 patients exhibited cognitive decline: four (Group A) exhibited core clinical features of dementia with Lewy bodies (DLB), along with severe cognitive decline, and were subsequently diagnosed as having probable DLB; four (Group B) did not exhibit core clinical features of DLB; and the remaining three (Group C) were diagnosed as having Parkinson's disease with dementia (PDD). Positron emission tomography with fluorodeoxyglucose-F18 at baseline revealed that Groups A and B exhibited glucose hypometabolism in the occipital lobe, especially in the primary visual cortex, and Group A tended to present hypometabolism in the parieto-temporal area as well. Group C tended to present hypometabolism in the medial prefrontal area and anterior cingulate gyrus. Neuropsychological examinations indicated poor performance in verbal memory and visuoperception in all groups. This case study suggests that patterns of hypometabolism and neuropsychological examinations at baseline may be indicators of the later clinical course of probable RBD patients.

Assessing cerebral glucose metabolism in patients with idiopathic rapid eye movement sleep behavior disorder

Idiopathic rapid eye movement sleep behavior disorder (RBD) is a risk marker for subsequent development of neurodegenerative parkinsonism. In this study, we aimed to investigate whether regional cerebral metabolism is altered in patients with RBD and whether regional metabolic activities are associated with clinical measurements in individual patients. Twenty-one patients with polysomnogram-confirmed RBD and 21 age-matched healthy controls were recruited to undertake positron emission tomography imaging with [(18)F]fluorodeoxyglucose. Differences in normalized regional metabolism and correlations between metabolic activity and clinical indices in RBD patients were evaluated on a voxel basis using statistic parametric mapping analysis. Compared with controls, patients with RBD showed increased metabolism in the hippocampus/parahippocampus, cingulate, supplementary motor area, and pons, but decreased metabolism in the occipital cortex/lingual gyrus (P<0.001). RBD duration correlated with metabolism positively in the anterior vermis (r=0.55, P=0.01), but negatively in the medial frontal gyrus (r=-0.59, P=0.005). In addition, chin electromyographic activity presented a positive metabolic correlation in the hippocampus/parahippocampus (r=0.48, P=0.02), but a negative metabolic correlation in the posterior cingulate (r=-0.61, P=0.002). This study has suggested that region-specific metabolic abnormalities exist in RBD patients and regional metabolic activities are associated with clinical measures such as RBD duration and chin electromyographic activity.

Cerebrospinal fluid α-synuclein and Lewy body-like symptoms in normal controls, mild cognitive impairment, and Alzheimer's disease

BACKGROUND

Reduced cerebrospinal fluid (CSF) α-synuclein has been described in synucleinopathies, including dementia with Lewy bodies (DLB). Common symptoms of DLB include visual hallucinations and visuospatial and executive deficits. Co-occurrence of Lewy body pathology is common in Alzheimer's disease (AD) patients, but it is unknown if reduced CSF α-synuclein is associated with Lewy body-like symptomatology in AD.

OBJECTIVE

Determine associations between CSF α-synuclein and Lewy body-like symptomatology.

METHODS

We included 73 controls (NC), 121 mild cognitive impairment (MCI) patients, and 61 AD patients (median follow-up 3.5 years, range 0.6-7.8). We tested associations between baseline CSF α-synuclein and visual hallucinations and (longitudinal) cognition. Models were tested with and without co-varying for CSF total tau (T-tau), which is elevated in AD patients, and believed to reflect neurodegeneration.

RESULTS

Hallucinations were reported in 20% of AD patients, 13% of MCI patients, and 8% of NC. In AD, low CSF α-synuclein was associated with hallucinations. When adjusting for CSF T-tau, low CSF α-synuclein was associated with accelerated decline of executive function (NC, MCI, and AD), memory (MCI and AD), and language (MCI).

CONCLUSION

The associations of low CSF α-synuclein with hallucinations and poor executive function, which are hallmarks of DLB, indirectly suggest that this biomarker may reflect underlying synuclein pathology. The associations with memory and language in MCI and AD suggests either that reduced CSF α-synuclein also partly reflects global impaired neuronal/synaptic function, or that non-specific overall cognitive deterioration is accelerated in the presence of synuclein related pathology. The findings will require autopsy verification.

Cortical Thickness in Dementia with Lewy Bodies and Alzheimer's Disease: A Comparison of Prodromal and Dementia Stages

Objectives

To assess and compare cortical thickness (CTh) of patients with prodromal Dementia with Lewy bodies (pro-DLB), prodromal Alzheimer's disease (pro-AD), DLB dementia (DLB-d), AD dementia (AD-d) and normal ageing.

Methods

Study participants(28 pro-DLB, 27 pro-AD, 31 DLB-d, 54 AD-d and 33 elderly controls) underwent 3Tesla T1 3D MRI and detailed clinical and cognitive assessments. We used FreeSurfer analysis package to measure CTh and investigate patterns of cortical thinning across groups.

Results

Comparison of CTh between pro-DLB and pro-AD (p<0.05, FDR corrected) showed more right anterior insula thinning in pro-DLB, and more bilateral parietal lobe and left parahippocampal gyri thinning in pro-AD. Comparison of prodromal patients to healthy elderly controls showed the involvement of the same regions. In DLB-d (p<0.05, FDR corrected) cortical thinning was found predominantly in the right temporo-parietal junction, and insula, cingulate, orbitofrontal and lateral occipital cortices. In AD-d(p<0.05, FDR corrected),the most significant areas affected included the entorhinal cortices, parahippocampal gyri and parietal lobes. The comparison of AD-d and DLB-d demonstrated more CTh in AD-d in the left entorhinal cortex (p<0.05, FDR corrected).

Conclusion

Cortical thickness is a sensitive measure for characterising patterns of grey matter atrophy in early stages of DLB distinct from AD. Right anterior insula involvement may be a key region at the prodromal stage of DLB and needs further investigation.

Prodromal dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementing disorder after Alzheimer's disease (AD), but there is limited information regarding the prodromal DLB state compared with that of AD. Parkinson's disease (PD) and DLB share common prodromal symptoms with Lewy body disease (LBD), allowing us to use a common strategy for identifying the individuals with an underlying pathophysiology of LBD. Dysautonomia, olfactory dysfunction, rapid eye movement sleep behavior disorder (RBD) and psychiatric symptoms antedate the onset of dementia by years or even decades in patients with DLB. Although RBD is the most potentially accurate prodromal predictor of DLB, disease progression before the onset of dementia could differ between the prodromal DLB state with and without RBD. Experts who specialize in idiopathic RBD and DLB might need communication in order to clarify the clinical relevance of RBD with the disease progression of DLB. The presence of prodromal LBD symptoms or findings of occipital hypoperfusion/hypometabolism helps us to predict the possible pathophysiological process of LBD in non-demented patients. This approach might provide the opportunity for additional neuroimaging, including cardiac (123) I-metaiodobenzylguanidine scintigraphy and dopamine transporter imaging. Although limited radiological findings in patients with prodromal DLB states have been reported, there is now a need for larger clinical multisite studies with pathological verification. The long prodromal phase of DLB provides a critical opportunity for potential intervention with disease-modifying therapy, but only if we are able to clearly identify the diversity in the clinical courses of DLB. In the present article, we reviewed the limited literature regarding the clinical profiles of prodromal DLB.

Multimodality imaging of Alzheimer disease and other neurodegenerative dementias

Neurodegenerative diseases, such as Alzheimer disease, result in cognitive decline and dementia and are a leading cause of mortality in the growing elderly population. These progressive diseases typically have an insidious onset, with overlapping clinical features early in the disease course that make diagnosis challenging. The neurodegenerative diseases are associated with characteristic, although not completely understood, changes in the brain: abnormal protein deposition, synaptic dysfunction, neuronal injury, and neuronal death. Neuroimaging biomarkers-principally regional atrophy on structural MR imaging, patterns of hypometabolism on (18)F-FDG PET, and detection of cerebral amyloid plaque on amyloid PET--are able to evaluate the patterns of these abnormalities in the brain to improve early diagnosis and help predict the disease course. These techniques have unique strengths and synergies in multimodality evaluation of the patient with cognitive decline or dementia. This review discusses the key imaging biomarkers from MR imaging, (18)F-FDG PET, and amyloid PET; the imaging features of the most common neurodegenerative dementias; the role of various neuroimaging studies in differential diagnosis and prognosis; and some promising imaging techniques under development.

Differential prefrontal and subcortical circuitry engagement during encoding of semantically related words in patients with late-life depression

OBJECTIVE

Verbal memory difficulties are common among individuals with late-life depression (LLD), though there is limited knowledge about disruptions to underlying cerebral circuitry. The purpose of this study is to examine aberrations to cerebral networks implicated in encoding novel verbal semantic material among older adults with LLD.

METHODS

Twenty-four older adults with early-onset LLD and 23 non-depressed comparisons participated in the study. Participants completed a word list-learning task while undergoing functional magnetic resonance imaging.

RESULTS

In the context of equivalent recall and recognition of words following scanning and similar hippocampal volumes, patients with LLD exhibited less activation in structures known to be relevant for new learning and memory, including hippocampus, parahippocampal gyrus, insula, and cingulate, relative to non-ill comparisons. An important region in which the LLD group displayed greater activation than the non-depressed comparison group was in left inferior frontal gyrus, an area involved in cognitive control and controlled semantic/phonological retrieval and analysis; this region may be critical for LLD patients to consolidate encoded words into memory.

CONCLUSIONS

Functional irregularities found in LLD patients may reflect different modes of processing to-be-remembered information and/or early changes predictive of incipient cognitive decline. Future studies might consider mechanisms that could contribute to these functional differences, including hypothalamic-pituitary-adrenal axis functioning and vascular integrity, and utilize longitudinal designs in order to understand whether functional changes are predictive of incipient cognitive decline.

The clinical characteristics of dementia with Lewy bodies and a consideration of prodromal diagnosis

Dementia with Lewy bodies (DLB) is the second most common type of degenerative dementia following Alzheimer’s disease (AD). DLB is clinically and pathologically related to Parkinson's disease (PD) and PD dementia, and the three disorders can be viewed as existing on a spectrum of Lewy body disease. In recent years there has been a concerted effort to establish the phenotypes of AD and PD in the prodromal phase (before the respective syndromes of cognitive and motor impairment are expressed). Evidence for the prodromal presentation of DLB is also emerging. This paper briefly reviews what is known about the clinical presentation of prodromal DLB before discussing the pathology of Lewy body disease and how this relates to potential biomarkers of prodromal DLB. The presenting features of DLB can be broadly placed in three categories: cognitive impairment (particularly nonamnestic cognitive impairments), behavioural/psychiatric phenomena (for example, hallucinations, rapid eye movement sleep behaviour disorder (RBD)) and physical symptoms (for example, parkinsonism, decreased sense of smell, autonomic dysfunction). Some noncognitive symptoms such as constipation, RBD, hyposmia and postural dizziness can predate the onset of memory impairment by several years in DLB. Pathological studies of Lewy body disease have found that the earliest sites of involvement are the olfactory bulb, the dorsal motor nucleus of the vagal nerve, the peripheral autonomic nervous system, including the enteric nervous system, and the brainstem. Some of the most promising early markers for DLB include the presence of RBD, autonomic dysfunction or hyposmia, ¹²³I-metaiodobenzylguanidine cardiac scintigraphy, measures of substantia nigra pathology and skin biopsy for α-synuclein in peripheral autonomic nerves. In the absence of disease-modifying therapies, the diagnosis of prodromal DLB is of limited use in the clinic. That said, knowledge of the prodromal development of DLB could help clinicians identify cases of DLB where the diagnosis is uncertain. Prodromal diagnosis is of great importance in research, where identifying Lewy body disease at an earlier stage may allow researchers to investigate the initial phases of dementia pathophysiology, develop treatments designed to interrupt the development of the dementia syndrome and accurately identify the patients most likely to benefit from these treatments.

Clinical and multimodal biomarker correlates of ADNI neuropathological findings

Background

Autopsy series commonly report a high percentage of coincident pathologies in demented patients, including patients with a clinical diagnosis of dementia of the Alzheimer type (DAT). However many clinical and biomarker studies report cases with a single neurodegenerative disease. We examined multimodal biomarker correlates of the consecutive series of the first 22 Alzheimer’s Disease Neuroimaging Initiative autopsies. Clinical data, neuropsychological measures, cerebrospinal fluid Aβ, total and phosphorylated tau and α-synuclein and MRI and FDG-PET scans.

Results

Clinical diagnosis was either probable DAT or Alzheimer’s disease (AD)-type mild cognitive impairment (MCI) at last evaluation prior to death. All patients had a pathological diagnosis of AD, but only four had pure AD. A coincident pathological diagnosis of dementia with Lewy bodies (DLB), medial temporal lobe pathology (TDP-43 proteinopathy, argyrophilic grain disease and hippocampal sclerosis), referred to collectively here as MTL, and vascular pathology were present in 45.5%, 40.0% and 22.7% of these patients, respectively. Hallucinations were a strong predictor of coincident DLB (100% specificity) and a more severe dysexecutive profile was also a useful predictor of coincident DLB (80.0% sensitivity and 83.3% specificity). Occipital FDG-PET hypometabolism accurately classified coincident DLB (80% sensitivity and 100% specificity). Subjects with coincident MTL showed lower hippocampal volume.

Conclusions

Biomarkers can be used to independently predict coincident AD and DLB pathology, a common finding in amnestic MCI and DAT patients. Cohorts with comprehensive neuropathological assessments and multimodal biomarkers are needed to characterize independent predictors for the different neuropathological substrates of cognitive impairment.