Clinical and striatal dopamine transporter predictors of β-amyloid in dementia with Lewy bodies

Regional Burden of Enlarged Perivascular Spaces and Cognition and Neuropsychiatric Symptoms in Drug-Naive Patients With Parkinson Disease

BACKGROUND AND OBJECTIVES

Although the potential role of enlarged perivascular spaces (EPVSs) in Parkinson disease (PD) is increasingly recognized, whether EPVSs located in different anatomical regions exert differential effects on clinical manifestation remains uncertain. We investigated the regional EPVS burden and its association with cognition and neuropsychiatric symptoms (NPSs) in newly diagnosed PD population.

METHODS

In this retrospective, cross-sectional study, EPVS in the temporal lobe (T-EPVS), centrum semiovale (CS-EPVS), and basal ganglia (BG-EPVS) were visually rated in drug-naive patients with PD who underwent magnetic resonance imaging, dopamine transporter (DAT) scans, neuropsychological assessments, and Neuropsychiatric Inventory Questionnaire at baseline. Cognitive performance, NPS burden, vascular risk factors, small vessel disease (SVD) imaging markers, and DAT availability were compared across groups dichotomized by their regional EPVS burden (cutoff for high-degree vs low-degree: >10 for T-EPVS/BG-EPVS and >20 for CS-EPVS).

RESULTS

A total of 480 patients with PD (123 without cognitive impairment, 291 with mild cognitive impairment, and 66 with dementia) were included. The proportion of high-degree T-EPVS (p for trend <0.001) and BG-EPVS (p for trend = 0.001) exhibited an increasing trend across the cognitive spectrum, corresponding to worsening cognition. Compared with the low-degree group, the high-degree BG-EPVS group showed higher SVD burden (moderate-to-severe white matter hyperintensity [14.8% vs 40.5%, p < 0.001], lacune [10.3% vs 30.7%, p < 0.001], and cerebral microbleeds [8.1% vs 22.2%, p < 0.001]), greater atrophy in cortical gray matter (40.73% ± 1.09% vs 39.96% ± 1.20% of intracranial volume, p < 0.001), and lower cognitive performance (in language [-0.22 ± 1.18 vs -0.53 ± 1.29, p = 0.013], and visual memory domains [-0.24 ± 0.97 vs -0.61 ± 0.96, p = 0.009]). The high-degree T-EPVS group presented with greater NPS burden in decreased motivation (0.61 ± 1.78 vs 1.35 ± 2.36, p = 0.007), affective dysregulation (0.88 ± 2.13 vs 2.36 ± 3.53, p < 0.001), and impulse dyscontrol (0.43 ± 1.67 vs 1.74 ± 4.29, p < 0.001), compared with the low-degree T-EPVS group. Meanwhile, the burden of CS-EPVS did not reveal any differences in cognition or NPS.

DISCUSSION

BG-EPVS and T-EPVS seem to exert differential effects on cognition and NPS in patients with PD. Investigating the EPVS profile in distinct anatomical regions may be useful in disentangling the heterogeneity within PD.

International consensus on clinical use of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

PURPOSE

Presynaptic dopaminergic positron emission tomography (PET) imaging serves as an essential tool in diagnosing and differentiating patients with suspected parkinsonism, including idiopathic Parkinson's disease (PD) and other neurodegenerative and non-neurodegenerative diseases. The PET tracers most commonly used at the present time mainly target dopamine transporters (DAT), aromatic amino acid decarboxylase (AADC), and vesicular monoamine type 2 (VMAT2). However, established standards for the imaging procedure and interpretation of presynaptic dopaminergic PET imaging are still lacking. The goal of this international consensus is to help nuclear medicine practitioners procedurally perform presynaptic dopaminergic PET imaging.

METHOD

A multidisciplinary task group formed by experts from various countries discussed and approved the consensus for presynaptic dopaminergic PET imaging in parkinsonism, focusing on standardized recommendations, procedures, interpretation, and reporting.

CONCLUSION

This international consensus and practice guideline will help to promote the standardized use of presynaptic dopaminergic PET imaging in parkinsonism. It will become an international standard for this purpose in clinical practice.

Effects of amyloid beta and dopaminergic depletion on perfusion and clinical symptoms

INTRODUCTION

Although mixed pathologies are common in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), the effects of amyloid beta and dopaminergic depletion on brain perfusion and clinical symptoms have not been elucidated.

METHODS

In 99 cognitive impairment patients due to AD and/or DLB and 32 controls, 18F-florbetaben (FBB) and dual-phase dopamine transporter (DAT) positron emission tomography (PET) were performed to measure the FBB standardized uptake value ratio (SUVR), striatal DAT uptakes, and brain perfusion.

RESULTS

Higher FBB-SUVR and lower ventral striatal DAT uptake were intercorrelated and, respectively, associated with left entorhinal/temporo-parietal-centered hypoperfusion and vermis/hippocampal-centered hyperperfusion, whereas regional perfusion mediated clinical symptoms and cognition.

DISCUSSION

Amyloid beta deposition and striatal dopaminergic depletion contribute to regional perfusion changes, clinical symptoms, and cognition in the spectrum of normal aging and cognitive impairment due to AD and/or LBD.

HIGHLIGHTS

Amyloid beta (Aβ) deposition was associated with ventral striatal dopaminergic depletion. Aβ deposition and dopaminergic depletion correlated with perfusion. Aβ deposition correlated with hypoperfusion centered in the left entorhinal cortex. Dopaminergic depletion correlated with hyperperfusion centered in the vermis. Perfusion mediated the Aβ deposition/dopaminergic depletion's effects on cognition.

Striatal dopamine transporter uptake, parkinsonism and cognition in Alzheimer's disease

BACKGROUND AND PURPOSE

The correlates of motor parkinsonism in Alzheimer's disease (AD) remain controversial. The effects of nigrostriatal dopaminergic degeneration on parkinsonism and cognition in biomarker-validated patients with AD were evaluated.

METHODS

This study recruited 116 patients with AD who underwent dual-phase 18 F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane positron emission tomography, 18 F-florbetaben positron emission tomography, 3 T brain magnetic resonance imaging, and Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological tests. The mean cortical thickness in the frontal, temporal, parietal and occipital cortices, and the dopamine transporter (DAT) uptake in the caudate, anterior/posterior putamen and substantia nigra were quantified. The relationship between DAT uptake, mean lobar cortical thickness, UPDRS motor score and cognition was investigated using general linear models (GLMs) after controlling for age, sex, education, intracranial volume, and deep and periventricular white matter hyperintensities. A path analysis was performed for the UPDRS motor score with the same covariates.

RESULTS

Path analysis and multivariable GLMs for UPDRS motor score showed that lower caudate DAT uptake was directly associated with a higher UPDRS motor score, whereas caudate DAT uptake confounded the association between mean frontal/parietal thickness and UPDRS motor score. Multivariable GLMs for cognitive scores showed that lower caudate DAT uptake was associated with visuospatial/executive dysfunction independent of mean frontal or parietal thickness.

CONCLUSIONS

Nigrostriatal dopaminergic dysfunction is associated with parkinsonism and visuospatial/executive dysfunction in patients with AD.

Distinct amyloid-dependent patterns of nigra dopamine depletion in Lewy body diseases

Introduction

Concomitant amyloid pathology is not uncommon and contributes to the clinical characteristics of Lewy body disease (LBD). We investigated the effect of amyloid on striatal18F-FP-CIT uptake patterns in LBD, including Parkinson's disease (PD) and dementia with Lewy bodies.

Methods

We enrolled 125 patients with LBD who underwent18F-florbetaben positron emission tomography (PET) and18F-FP-CIT PET. Patients were divided into amyloid-positive and amyloid-negative groups. We investigated the effect of amyloid on striatal dopamine transporter (DAT) availability, depending on the type of LBD, using general linear models with interaction analysis after controlling for age, sex, education, deep white matter hyperintensity (WMH), periventricular WMH, and cognitive status.

Results

There was a significant interaction effect between the disease group and the presence of amyloid on DAT availability in the anterior putamen, posterior putamen, caudate, and ventral striatum. In the presence of amyloid, only the PD group exhibited decreased DAT availability in the anterior and posterior putamen. In both groups, the presence of amyloid was not associated with DAT availability in the caudate and ventral striatum. The presence of amyloid was not directly related to the worse parkinsonian motor symptoms in both groups. However, there was a significant indirect effect of amyloid on parkinsonian motor symptoms, which was mediated by anterior and posterior putaminal DAT availability in the PD group alone.

Discussion

This study demonstrates different amyloid-dependent or amyloid-independent18F-FP-CIT PET patterns in patients with LBD, suggesting distinctive interactions between α-synuclein and amyloid pathology based on the type of LBD.

60 Years of Achievements by KSNM in Neuroimaging Research

Nuclear medicine neuroimaging is able to show functional and molecular biologic abnormalities in various neuropsychiatric diseases. Therefore, it has played important roles in the clinical diagnosis and in research on the normal and pathological states of the brain. More than 400 outstanding studies have been conducted by Korean researchers over the past 60 years. In the 1990s, when multiheaded single-photon emission computed tomography (SPECT) scanners were first introduced in South Korea, stroke research using brain perfusion SPECT was conducted. With the spread of positron emission tomography (PET) scanners in the 2000s, research on the clinical usefulness of PET and the evaluation of pathophysiology in various diseases such as epilepsy, brain tumors, degenerative brain diseases, and other neuropsychiatric diseases were actively conducted using [¹⁸F]FDG and various neuroreceptor tracers. In the 2010s, with the clinical application of new radiopharmaceuticals for amyloid and tau imaging, research demonstrating the clinical usefulness of PET imaging and the pathophysiology of dementia has increased rapidly. It is expected that the role of nuclear medicine will expand with the development of new radiopharmaceuticals and analysis technologies, along with the application of artificial intelligence for early and differential diagnosis, and the development of therapeutic agents for degenerative brain diseases.

Characteristics of Bipolar Patients with Cognitive Impairment of Suspected Neurodegenerative Origin: A Multicenter Cohort

Bipolar disorder is associated with an increased risk of dementia with aging. Little is known regarding this association, limiting appropriate diagnosis and management. We aimed to describe the characteristics of bipolar patients with late cognitive impairment for whom the hypothesis of an underlying neurodegenerative disease had been raised. We performed a retrospective multicenter study, recruiting bipolar patients over 50 years old from five French tertiary memory centers who had undergone cerebrospinal fluid (CSF) biomarker assessment for Alzheimer’s disease (AD). Clinical, neuropsychological, and paraclinical characteristics were analyzed and 78 patients were included. The mean age at the onset of cognitive impairment was 62.4 years (±9.2). The mean MMSE score was 22.8 (±4.5), the mean FAB was 11.7 (±3.9), and the mean FCRST was 15.8 (±7.4)/36.8 (±9.7) (free/total recall). A total of 48.6% of the patients displayed cognitive fluctuations, and 38.2% showed cognitive improvement during follow-ups; and 56.3% of the patients showed Parkinsonism, of which 12.7% had never received antipsychotics. Among patients who underwent DAT-scans, 35.3% displayed dopaminergic denervation; 10.3% of patients had CSF AD biological signature (“A+ T+” profile), while 56.4% had other abnormal CSF profiles. Thus, clinical presentation was dominated by executive dysfunction, episodic memory impairment, fluctuating cognition, and a high frequency of Parkinsonism. Specifically, high frequency of delusional episodes suggests limited tolerance of psychotropic drugs. Most patients had abnormal CSF biomarker profiles, but only a minority displayed AD’s specific biomarker signature. Therefore, while our results unveil shared common neurocognitive features in bipolar patients with cognitive impairment of suspected neurodegenerative origin they suggest a participation of various underlying pathologies rather than a common degenerative mechanism in the pathophysiology of this condition.

Clinico-pathological comparison of patients with autopsy-confirmed Alzheimer's disease, dementia with Lewy bodies, and mixed pathology

INTRODUCTION

Patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) frequently demonstrate coexistent AD neuropathological change (ADNC) and Lewy body pathology (LBP) at autopsy. We investigated the effects of ADNC and LBP on the clinical presentation of these patients.

METHODS

We retrospectively compared clinical and pathological features of patients with different severity of ADNC and LBP. We also compared the burden of medullary LBP between patients with and without autonomic dysfunction.

RESULTS

Compared to pure ADNC, patients with AD/LBP have higher prevalence of DLB symptoms. Autonomic dysfunction strongly predicted the presence of LBP in patients with clinically diagnosed AD, but was not associated with increased LBP burden in the medulla. Severity of ADNC, but not LBP, was associated with cerebral atrophy.

DISCUSSION

Clinical presentation of patients with AD/LBP differs from patients with pure ADNC or LBP. Autonomic dysfunction is a useful marker of otherwise unsuspected LBP.

Significance of cerebral amyloid angiopathy and other co-morbidities in Lewy body diseases

Lewy body dementia (LBD) and Parkinson's disease-dementia (PDD) are two major neurocognitive disorders with Lewy bodies (LB) of unknown etiology. There is considerable clinical and pathological overlap between these two conditions that are clinically distinguished based on the duration of Parkinsonism prior to development of dementia. Their morphology is characterized by a variable combination of LB and Alzheimer's disease (AD) pathologies. Cerebral amyloid angiopathy (CAA), very common in aged persons and particularly in AD, is increasingly recognized for its association with both pathologies and dementia. To investigate neuropathological differences between LB diseases with and without dementia, 110 PDD and 60 LBD cases were compared with 60 Parkinson's disease (PD) cases without dementia (PDND). The major demographic and neuropathological data were assessed retrospectively. PDD patients were significantly older than PDND ones (83.9 vs 77.8 years; p < 0.05); the age of LB patients was in between both groups (mean 80.2 years), while the duration of disease was LBD < PDD < PDND (mean 6.7 vs 12.5 and 14.3 years). LBD patients had higher neuritic Braak stages (mean 5.1 vs 4.5 and 4.0, respectively), LB scores (mean 5.3 vs 4.2 and 4.0, respectively), and Thal amyloid phases (mean 4.1 vs 3.0 and 2.3, respectively) than the two other groups. CAA was more common in LBD than in the PDD and PDND groups (93 vs 50 and 21.7%, respectively). Its severity was significantly greater in LBD than in PDD and PDND (p < 0.01), involving mainly the occipital lobes. Moreover, striatal Aβ deposition highly differentiated LBD brains from PDD. Braak neurofibrillary tangle (NFT) stages, CAA, and less Thal Aβ phases were positively correlated with LB pathology (p < 0.05), which was significantly higher in LBD than in PDD < PDND. Survival analysis showed worse prognosis in LBD than in PDD (and PDND), which was linked to both increased Braak tau stages and more severe CAA. These and other recent studies imply the association of CAA-and both tau and LB pathologies-with cognitive decline and more rapid disease progression that distinguishes LBD from PDD (and PDND).

The Association of β-Amyloid with Cognition and Striatal Dopamine in Early, Non-Demented Parkinson's Disease

BACKGROUND

Co-occurrence of β-amyloid (Aβ) pathology has been reported in Parkinson's disease (PD), and Aβ deposition in the brain may contribute to cognitive decline in patients with PD. Whether striatal dopamine uptake and cognitive status differ with amyloid deposition has been reported in only a few studies.

OBJECTIVE

The purpose of this study was to investigate the association among striatal dopaminergic availability, Aβ-positivity, and motor and cognitive status in early and non-demented PD.

METHODS

A total of 98 newly-diagnosed, non-medicated, and non-demented patients with PD were included in this study. Cognitive status was assessed using neuropsychological testing. Patients with mild cognitive impairment (MCI) were stratified into two groups: amnestic MCI (aMCI) and non-amnestic MCI (naMCI). Patient motor status was examined using the Unified Parkinson's Disease Rating Scale (UPDRS) and positron emission tomography (PET) with 18F-N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane (18F-FP-CIT). All patients also underwent 18F-florbetaben (18F-FBB) PET and were divided based on the results into Aβ-positive and Aβ-negative groups.

RESULTS

Eighteen patients had Aβ-positivity in 18F-FBB PET and 67 had MCI. Sixteen of 18 with Aβ-positive patients had MCI. The Aβ-positive group had higher frequency of MCI, especially amnestic-type, and lower dopaminergic activities in the left ventral striatum, but not with UPDRS motor score.

CONCLUSION

Amyloid pathology was associated with MCI, especially amnestic-subtype, in early and non-demented PD patients and with low dopaminergic activities in the left ventral striatum. This finding suggests that PD patients with Aβ-positivity have AD-related cognitive pathophysiology in PD and associated impaired dopaminergic availability in the ventral striatum can affect the pathophysiology in various ways.

Differentiating dementia with Lewy bodies from Alzheimer's disease and Parkinson's disease dementia: an update on imaging modalities

Dementia with Lewy bodies is the second most common cause of neurodegenerative dementia after Alzheimer's disease. Dementia with Lewy bodies can provide a diagnostic challenge due to the frequent overlap of clinical signs with other neurodegenerative conditions, namely Parkinson's disease dementia, and Alzheimer's disease. Part of this clinical overlap is due to the neuropathological overlap. Dementia with Lewy bodies is characterized by the accumulation of aggregated α-synuclein protein in Lewy bodies, similar to Parkinson's disease and Parkinson's disease dementia. However, it is also frequently accompanied by aggregation of amyloid-beta and tau, the pathological hallmarks of Alzheimer's disease. Neuroimaging is central to the diagnostic process. This review is an overview of both established and evolving imaging methods that can improve diagnostic accuracy and improve management of this disorder.

Dopaminergic Correlates of Orthostatic Hypotension in de novo Parkinson's Disease

BACKGROUND

Orthostatic hypotension (OH) at an early stage of Parkinson's disease (PD) predicts poor prognosis, which may suggest degeneration of dopaminergic neurons affects sympathetic function, causing OH.

OBJECTIVE

We tested the hypothesis that striatal dopaminergic depletion is associated with OH in PD.

METHODS

Out of 99 patients with newly diagnosed untreated PD, 81 patients were enrolled according to our selection criteria. All patients underwent head-up tilt-table testing and striatal 123I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (123I-FP-CIT) dopamine transporter single photon emission computed tomography (DAT-SPECT). DaTQUANT software (GE Healthcare) was used as a semi-quantitative tool to analyze DAT-SPECT data. The association between hemodynamic changes and 123I-FP-CIT uptake was examined.

RESULTS

123I-FP-CIT uptake in the putamen, especially the anterior part and left side, was related not only to motor severity but also to OH. Change in systolic blood pressure correlated negatively with 123I-FP-CIT uptake in bilateral anterior putamen (left: p < 0.01, right: p < 0.05) and left posterior putamen (p < 0.05). Patients with OH had more severe dopamine depletion in left anterior (p = 0.008) and posterior (p = 0.007) putamen at a similar motor severity than did patients without OH even though both groups have similar baseline characteristics. An analysis of asymmetry index showed patients with OH had symmetrically decreased dopamine levels in anterior putamen when compared to those without OH (p = 0.024).

CONCLUSION

OH is closely related to striatal dopamine depletion in PD. This relation may help to account for the prognostic value of OH.

The pattern of FP-CIT PET in pure white matter hyperintensities-related vascular parkinsonism

OBJECTIVES

To determine whether vascular parkinsonism (VaP) patients with visually normal dopamine transporter (DAT) scans have presynaptic dopaminergic depletion.

METHODS

We enrolled 23 VaP patients who had parkinsonism, relevant diffuse subcortical white matter hyperintensities (WMH), and visually normal DAT scans, 23 Parkinson's disease (PD) patients, and 31 control subjects. By quantitatively analyzing ¹⁸F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane (¹⁸F-FP-CIT) positron emission tomography, we compared the pattern of striatal DAT availability among groups. The discriminatory power of striatal DAT availability to differentiate VaP patients from control subjects or PD patients was assessed using receiver operating characteristics (ROC) analyses. Additionally, correlation analysis was performed to determine whether WMH severity or Unified Parkinson Disease Rating Scale Part III (UPDRS-III) score is related to presynaptic dopaminergic depletion in VaP.

RESULTS

VaP patients exhibited decreased DAT availability in all striatal subregions, including posterior putamen, compared to control subjects. VaP patients and control subjects had similar patterns of anteroposterior and ventrodorsal DAT gradients in caudate and putamen level, but VaP patients exhibited significantly different patterns at putamen level, relative to PD patients. The severity of periventricular WMH was significantly correlated with all substriatal DAT availability in VaP, but not with UPDRS-III scores. The ROC analysis showed that DAT availability in caudate and posterior putamen had a fair discriminatory power when differentiating VaP patients from control subjects.

CONCLUSIONS

This study demonstrates that VaP patients with WMH exhibited diffusely decreased DAT availability without any specific regional gradients of DAT patterns distinct from either control subjects or PD patients.