High prevalence of parkinsonism in patients with MCI or mild Alzheimer's disease

Pathologically Confirmed Alzheimer's Disease Presenting as Clinical Parkinson's Disease, A Case Report

BACKGROUND

It is well known that rare cases of Alzheimer's disease (AD) pathology may cause corticobasal or posterior cortical atrophy syndromes, and that cases with advanced AD may develop parkinsonism. However, reports of parkinsonism as an initial manifestation of AD have rarely been documented.

OBJECTIVES

To demonstrate that a syndrome meeting all criteria for a clinical diagnosis of idiopathic Parkinson's disease (PD) may be an initial and years-long sustained manifestation of pathologically confirmed AD.

METHODS

Clinico-pathological case.

RESULTS

We present a case with a 12-year clinical presentation consistent with a typical course of idiopathic Parkinson's disease, including dementia developing 6 years after the PD diagnosis. The patient improved, but only mildly, to standard treatment for PD motor symptoms. The neuropathological examination identified AD changes, and no evidence to support a concomitant diagnosis of PD.

CONCLUSIONS

The absence of alpha-synucleinopathy, coupled with the patient's dementia history and AD changes in neuropathological examination, indicated the diagnosis of AD and no supplementary explanation. Neuronal loss with neurofibrillary tangles and amyloid plaques in the brainstem, substantia nigra, and locus coeruleus likely contributed to Parkinsonism features.

Long-term follow-up study of SWEDD patients with mild parkinsonian signs

Background

Whether scan without evidence of dopaminergic deficit (SWEDD) can be a reliable indication of a clinical entity of Parkinson's disease (PD) is controversial.

Objective

To evaluate the proportion of SWEDD patients with mild parkinsonian signs who are classifiable as idiopathic PD.

Methods

32 SWEDD patients with unilateral or asymmetric finger tremor with a rest component and unilateral rigidity (Unified Parkinson's Disease Rating Scale (UPDRS)-III scores of 3-5) were enrolled. They underwent longitudinal examination by UPDRS-III, Mini-Mental State Examination (MMSE), smell test and 123I-FP-CIT SPECT (DaTSCAN) at baseline (first DaTSCAN) and at follow-up (second DaTSCAN) after 27-83 months. Age-matched controls (n=112) also underwent MMSE and smell test.

Results

At follow-up, 21 of 32 SWEDD patients (65.6%) showed significantly reduced specific binding ratios below the normal range, that is, positive DaTSCAN, sometimes with increased asymmetry index (n=11). Among these 21 patients, the mean (SD) UPDRS-III score at follow-up was significantly higher than that at baseline (5.5 (2.2) vs 4.0 (0.5)) (p=0.003). The mean (SD) MMSE scores in SWEDD patients (n=32) at baseline and follow-up were not significantly different compared with those in controls. Olfactory function both in SWEDD patients with positive and negative DaTSCAN was significantly impaired versus controls (p<0.001), although no significant difference was recognised between patients with positive (n=21) and negative (n=11) second DaTSCAN.

Conclusion

The majority of SWEDD patients with mild rest tremor and rigidity could be classified as having idiopathic PD in this longitudinal and long-term follow-up study.

Firing Alterations of Neurons in Alzheimer's Disease: Are They Merely a Consequence of Pathogenesis or a Pivotal Component of Disease Progression?

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, yet its underlying causes remain elusive. The conventional perspective on disease pathogenesis attributes alterations in neuronal excitability to molecular changes resulting in synaptic dysfunction. Early hyperexcitability is succeeded by a progressive cessation of electrical activity in neurons, with amyloid beta (Aβ) oligomers and tau protein hyperphosphorylation identified as the initial events leading to hyperactivity. In addition to these key proteins, voltage-gated sodium and potassium channels play a decisive role in the altered electrical properties of neurons in AD. Impaired synaptic function and reduced neuronal plasticity contribute to a vicious cycle, resulting in a reduction in the number of synapses and synaptic proteins, impacting their transportation inside the neuron. An understanding of these neurophysiological alterations, combined with abnormalities in the morphology of brain cells, emerges as a crucial avenue for new treatment investigations. This review aims to delve into the detailed exploration of electrical neuronal alterations observed in different AD models affecting single neurons and neuronal networks.

Dopamine transporter positron emission tomography in patients with Alzheimer's disease with Lewy body disease features

In 36 normal controls (NC), 37 patients with Alzheimer's disease (AD) without parkinsonism (ADP-), 31 AD with parkinsonism (ADP+), and 40 AD with dementia with Lewy bodies (ADDLB), dual-phase dopamine transporter (DAT) positron emission tomography (PET) were performed to evaluate the diagnostic performance of DAT and early-to-delayed uptake ratios (E/Ds) in the anterior caudate (AC), posterior caudate (PC), anterior putamen (AP), posterior putamen (PP), and substantia nigra (SN) to differentiate ADP+/ADDLB from NC, and their effects on parkinsonism and cognition. DAT-SN and E/D-PP showed higher accuracies to differentiate ADP+/ADDLB from NC than DAT-PP. Among AD patients, lower DAT in the putamen and PC and higher E/Ds in the striatum were associated with severe parkinsonism, while higher E/Ds in the putamen, PC, and SN were associated with executive dysfunction. Our results suggest that decreased DAT-SN and increased E/D-PP could be biomarkers differentiating ADP+/ADDLB from pure AD and controls. Meanwhile, increased E/Ds in the putamen could reflect the severity of DLB presenting with parkinsonism and executive dysfunction among AD patients.

Neuropsychological Comparison of Patients With Alzheimer's Disease and Dementia With Lewy Bodies

BACKGROUND AND PURPOSE

This study aimed to determine the neuropsychological differences between patients with early-stage Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) with a Clinical Dementia Rating (CDR) score of ≤1.

METHODS

We examined 168 patients with AD (126 with CDR score=0.5, 42 with CDR score=1) and 169 patients with DLB (104 with CDR score=0.5, 65 with CDR score=1) whose diagnoses were supported by 18F-flobetaben positron-emission tomography (PET) and 18F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane PET. Neuropsychological test scores were compared after controlling for age, sex, and education duration. Using a cutoff motor score on the Unified Parkinson's Disease Rating Scale of 20, patients with AD were further divided into AD with parkinsonism (ADP+, n=86) and AD without parkinsonism (ADP-, n=82).

RESULTS

At CDR scores of both 0.5 and 1, the DLB group had lower scores on the attention (digit-span forward at CDR score=0.5 and backward at CDR score=1), visuospatial, and executive (color reading Stroop test at CDR score=0.5 and phonemic fluency test, Stroop tests, and digit symbol coding at CDR score=1) tests than the AD group, but higher scores on the memory tests. The ADP- and ADP+ subgroups had comparable scores on most neuropsychological tests, but the ADP+ subgroup had lower scores on the color reading Stroop test.

CONCLUSIONS

Patients with DLB had worse attention, visuospatial, and executive functions but better memory function than patients with AD. Parkinsonism was not uncommon in the patients with AD and could be related to attention and executive dysfunction.

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.

Motor Symptoms in Early- versus Late-Onset Alzheimer's Disease

BACKGROUND

Age at onset was suggested as one possible risk factor for motor dysfunction in Alzheimer's disease (AD).

OBJECTIVE

We investigated the association of motor symptoms with cognition or neurodegeneration in patients with AD, and whether this association differs by the age at onset.

METHODS

We included 113 amyloid positive AD patients and divided them into early-onset AD (EOAD) and late-onset AD (LOAD), who underwent the Unified Parkinson's Disease Rating Scale (UPDRS)-Part III (=UPDRS) scoring, Mini-Mental State Examination (MMSE)/Clinical Deterioration Rating Sum-of-Boxes (CDR-SOB), and magnetic resonance image (MRI). Multiple linear regression was used to evaluate the association of UPDRS and MMSE/CDR-SOB or MRI neurodegeneration measures, and whether the association differs according to the group.

RESULTS

The prevalence of motor symptoms and their severity did not differ between the groups. Lower MMSE (β= -1.1, p < 0.001) and higher CDR-SOB (β= 2.0, p < 0.001) were significantly associated with higher UPDRS. There was no interaction effect between MMSE/CDR-SOB and AD group on UPDRS. Global or all regional cortical thickness and putaminal volume were negatively associated with UPDRS score, but the interaction effect of neurodegeneration and AD group on UPDRS score was significant only in parietal lobe (p for interaction = 0.035), which showed EOAD to have a more pronounced association between parietal thinning and motor symptoms.

CONCLUSION

Our study suggested that the severity of motor deterioration in AD is related to the severity of cognitive impairment itself rather than age at onset, and motor symptoms might occur through multiple mechanisms including cortical and subcortical atrophy.

Pathological mechanisms and therapeutic strategies for Alzheimer's disease

Alzheimer's disease is a rather complex neurodegenerative disease, which is attributed to a combination of multiple factors. Among the many pathological pathways, synaptic dysfunctions, such as synapses loss and deficits in synaptic plasticity, were thought to be strongly associated with cognitive decline. The deficiencies in various sorts of neurotransmissions are responsible for the multifarious neurodegenerative symptoms in Alzheimer's disease, for example, the cholinergic and glutamatergic deficits for cognitive decline, the excitatory and inhibitory neurotransmission dyshomeostasis for synaptic plasticity deficits and epileptiform symptoms, and the monoamine neurotransmission for neuropsychiatric symptoms. Amyloid cascade hypothesis is the most popular pathological theory to explain Alzheimer's disease pathogenesis and attracts considerable attention. Multiple lines of genetic and pathological evidence support the predominant role of amyloid beta in Alzheimer's disease pathology. Neurofibrillary tangles assembled by microtubule-associated protein tau are other important histopathological characteristics in Alzheimer's disease brains. Cascade of tau toxicity was proved to lead to neuron damage, neuroinflammation and oxidative stress in brain. Ageing is the main risk factor of neurodegenerative diseases, and is associated with inflammation, oxidative stress, reduced metabolism, endocrine insufficiencies and organ failures. These aging related risk factors were also proved to be some of the risk factors contributing to Alzheimer's disease. In Alzheimer's disease drug development, many good therapeutic strategies have been investigated in clinical evaluations. However, complex mechanism of Alzheimer's disease and the interplay among different pathological factors call for the come out of all-powerful therapies with multiple curing functions. This review seeks to summarize some of the representative treatments targeting different pathological pathways currently under clinical evaluations. Multi-target therapies as an emerging strategy for Alzheimer's disease treatment will be highlighted.

It Is Time to Study Overlapping Molecular and Circuit Pathophysiologies in Alzheimer's and Lewy Body Disease Spectra

Alzheimer's disease (AD) is the leading cause of dementia due to neurodegeneration and is characterized by extracellular senile plaques composed of amyloid β1 - 42 (Aβ) as well as intracellular neurofibrillary tangles consisting of phosphorylated tau (p-tau). Dementia with Lewy bodies constitutes a continuous spectrum with Parkinson's disease, collectively termed Lewy body disease (LBD). LBD is characterized by intracellular Lewy bodies containing α-synuclein (α-syn). The core clinical features of AD and LBD spectra are distinct, but the two spectra share common cognitive and behavioral symptoms. The accumulation of pathological proteins, which acquire pathogenicity through conformational changes, has long been investigated on a protein-by-protein basis. However, recent evidence suggests that interactions among these molecules may be critical to pathogenesis. For example, Aβ/tau promotes α-syn pathology, and α-syn modulates p-tau pathology. Furthermore, clinical evidence suggests that these interactions may explain the overlapping pathology between AD and LBD in molecular imaging and post-mortem studies. Additionally, a recent hypothesis points to a common mechanism of prion-like progression of these pathological proteins, via neural circuits, in both AD and LBD. This suggests a need for understanding connectomics and their alterations in AD and LBD from both pathological and functional perspectives. In AD, reduced connectivity in the default mode network is considered a hallmark of the disease. In LBD, previous studies have emphasized abnormalities in the basal ganglia and sensorimotor networks; however, these account for movement disorders only. Knowledge about network abnormalities common to AD and LBD is scarce because few previous neuroimaging studies investigated AD and LBD as a comprehensive cohort. In this paper, we review research on the distribution and interactions of pathological proteins in the brain in AD and LBD, after briefly summarizing their clinical and neuropsychological manifestations. We also describe the brain functional and connectivity changes following abnormal protein accumulation in AD and LBD. Finally, we argue for the necessity of neuroimaging studies that examine AD and LBD cases as a continuous spectrum especially from the proteinopathy and neurocircuitopathy viewpoints. The findings from such a unified AD and Parkinson's disease (PD) cohort study should provide a new comprehensive perspective and key data for guiding disease modification therapies targeting the pathological proteins in AD and LBD.

Dopaminergic dysfunction in the 3xTg-AD mice model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by amyloid (Aβ) protein aggregation and neurofibrillary tangles accumulation, accompanied by neuroinflammation. With all the therapeutic attempts targeting these biomarkers having been unsuccessful, the understanding of early mechanisms involved in the pathology is of paramount importance. Dopaminergic system involvement in AD has been suggested, particularly through the appearance of dopaminergic dysfunction-related neuropsychiatric symptoms and an overall worsening of cognitive and behavioral symptoms. In this study, we reported an early dopaminergic dysfunction in a mouse model presenting both amyloid and Tau pathology. 3xTg-AD mice showed an increase of postsynaptic D_2/3R receptors density in the striatum and D_2/3-autoreceptors in SN/VTA cell bodies. Functionally, a reduction of anxiety-like behavior, an increase in locomotor activity and D₂R hyper-sensitivity to quinpirole stimulation have been observed. In addition, microglial cells in the striatum showed an early inflammatory response, suggesting its participation in dopaminergic alterations. These events are observed at an age when tau accumulation and Aβ deposits in the hippocampus are low. Thus, our results suggest that early dopaminergic dysfunction could have consequences in behavior and cognitive function, and may shed light on future therapeutic pathways of AD.

Motor Dysfunction Questionnaire and Dopamine Transporter Imaging Composite Scale Improve Differentiating Dementia With Lewy Bodies From Alzheimer's Disease With Motor Dysfunction

Objective: Characteristic parkinsonism is the major comorbidity of dementia with Lewy bodies (DLB). We aimed to differentiate DLB from Alzheimer's disease (AD) with motor dysfunction using a composite scale with a characteristic motor dysfunction questionnaire (MDQ) and dopamine transporter (DAT) imaging. It could help detect DLB easily in healthcare settings without movement disorder specialists.

Methods: This is a two-phase study. In the design phase, seven questions were selected and composed of a novel MDQ. In the test phase, all participants with DLB, AD, or non-dementia (ND) control completed dementia and parkinsonism survey, the novel designed questionnaire, DAT imaging, and composite scales of MDQ and DAT. The cutoff scores of the MDQ, semiquantitative analysis of the striatal–background ratio (SBR) and visual rating of DAT, and the composite scale of MDQ and DAT for discriminating DLB from AD or ND were derived and compared.

Results: A total of 277 participants were included in this study (126 with DLB, 86 with AD, and 65 with ND). Compared with the AD or ND groups, the DLB group showed a significantly higher frequency in all seven items in the MDQ and a significantly lower SBR. For discrimination of DLB from non-DLB with MDQ, SBR, and composite scale, the cutoff scores of 3/2, 1.37/1.38, and 6/5 were suggested for the diagnosis of DLB with the sensitivities/specificities of 0.91/0.72, 0.91/0.80, and 0.87/0.93, respectively. The composite scale significantly improved the accuracy of discrimination compared with either the MDQ or SBR.

Conclusion: This study showed that the novel designed simple questionnaire was a practical screening tool and had similar power to DAT scanning to detect DLB. The questionnaire can be applied in clinical practice and population studies for screening DLB. In addition, the composite scale of MDQ and DAT imaging further improved the diagnostic accuracy, indicating the superiority of the dual-model diagnostic tool.

High Prevalence of Early Parkinson's Disease in Patients With Subtle Parkinsonian Signs

Background: Little is known about how frequently patients with a Unified Parkinson Disease Rating Scale part III (UPDRS-III) score of 3 or 4, including postural and action tremor, could be classified into early Parkinson's disease (PD).

Objective: To examine the prevalence of early PD in patients with subtle parkinsonian signs (rest tremor, postural tremor, and rigidity) without bradykinesia, having a UPDRS-III score of 3 or 4.

Methods: Parkinsonism was assessed using UPDRS-III based on both the United Kingdom PD Society Brain Bank criteria and the Movement Disorder Society PD criteria. Ninety patients with a UPDRS-III score of 3 or 4, including postural tremor, were evaluated by ¹²³I-FP-CIT SPECT (DaTscan), brain MRI, the Mini-Mental State Examination, and smell test. Some patients were additionally examined by ¹²³I-metaiodobenzylguanidine myocardial scintigraphy or ¹²³I-N-isopropyl-p-iodoamphetamine SPECT.

Results: Seventy-five [mean age (standard deviation): 76.9 (8.1)] out of 90 patients (83.3%) showed abnormal findings on DaTscan imaging: 57 out of 75 (76.0%) showed a reduced specific binding ratio (SBR) accompanied by an egg shape pattern (n = 37, 49.3%) or a mixed type pattern (n = 14, 18.7%), both reduced SBR and increased asymmetry index (AI) with a normal shape (n = 4, 5.3%), and reduced SBR only (n = 2, 2.7%); 18 (24.0%) showed an egg shape pattern or a mixed type pattern without reduced SBR. In other words, 69 out of 75 patients (92.0%) showed either an egg shape or a mixed type pattern with or without reduced SBR. All patients were free of dementia, and their olfactory function was significantly impaired compared with controls (n = 141) on the odor-stick identification test for Japanese (p < 0.0001).

Conclusions: The prevalence of patients with subtle parkinsonian signs having a UPDRS-III score of 3 or 4, including postural tremor, is unexpectedly high in daily clinical practice, and most of these patients could be categorized into mild early-stage PD.

Motor signs in Alzheimer's disease and vascular dementia: Detection through natural language processing, co-morbid features and relationship to adverse outcomes

BACKGROUND

Motor signs in patients with dementia are associated with a higher risk of cognitive decline, institutionalisation, death and increased health care costs, but prevalences differ between studies. The aims of this study were to employ a natural language processing pipeline to detect motor signs in a patient cohort in routine care; to explore which other difficulties occur co-morbid to motor signs; and whether these, as a group and individually, predict adverse outcomes.

METHODS

A cohort of 11,106 patients with dementia in Alzheimer's disease, vascular dementia or a combination was assembled from a large dementia care health records database in Southeast London. A natural language processing algorithm was devised in order to establish the presence of motor signs (bradykinesia, Parkinsonian gait, rigidity, tremor) recorded around the time of dementia diagnosis. We examined the co-morbidity profile of patients with these symptoms and used Cox regression models to analyse associations with survival and hospitalisation, adjusting for twenty-four potential confounders.

RESULTS

Less than 10% of patients were recorded to display any motor sign, and tremor was most frequently detected. Presence of motor signs was associated with younger age at diagnosis, neuropsychiatric symptoms, poor physical health and higher prescribing of psychotropics. Rigidity was independently associated with a 23% increased mortality risk after adjustment for confounders (p = 0.014). A non-significant trend for a 15% higher risk of hospitalisation was detected in those with a recorded Parkinsonian gait (p = 0.094).

CONCLUSIONS

With the exception of tremor, motor signs appear to be under-recorded in routine care. They are part of a complex clinical picture and often accompanied by neuropsychiatric and functional difficulties, and thereby associated with adverse outcomes. This underlines the need to establish structured examinations in routine clinical practice via easy-to-use tools.

Gait Analysis of Old Individuals with Mild Parkinsonian Signs and Those Individuals' Gait Performance Benefits Little from Levodopa

Background and Purpose

Gait analysis and the effects of levodopa on the gait characteristics in Mild parkinsonian signs (MPS) are rarely published. The present research aimed to (1) analyze the gait characteristics in MPS; (2) explore the effects of levodopa on the gait performance of MPS.

Methods

We enrolled 22 inpatients with MPS and 20 healthy control subjects (HC) from Nanjing Brain Hospital. The Unified Parkinson’s Disease Rating Scale was used to evaluate motor symptoms. Acute levodopa challenge test was performed to explore the effects of levodopa on the gait performance of MPS. The instrumented stand and walk test was conducted for each participant and the JiBuEn gait analysis system was used to collect gait data.

Results

For spatiotemporal parameters: Compared with HC, the state before taking levodopa/benserazide in MPS group (meds-off) demonstrated a decrease in stride length (SL) (p≤0.001), an increase in SL variability (p≤0.001), and swing phase time variability (p=0.016). Compared with meds-off, the state after 1 hour of taking levodopa/benserazide in MPS group (meds-on) exhibited an increase in SL (p≤0.001), a decrease in SL variability (p≤0.001). For kinematic parameters: Compared with HC, meds-off demonstrated a decrease in heel strike angle (p=0.008), range of motion (ROM) of knee joint (p=0.011) and ROM of hip joint (p=0.007). Compared with meds-off, meds-on exhibited an increase in HS (p≤0.001). Bradykinesia and rigidity scores were significantly correlated with gait parameters.

Conclusion

Although the clinical symptoms of the MPS group are mild, their gait damage is obvious and they exhibited a decreased SL and joints movement, and a more variable gait pattern. Levodopa had little effect on the gait performance of those individuals.

Alterations in dopamine system and in its connectivity with serotonin in a rat model of Alzheimer's disease

Dopamine pathways alterations are reported in Alzheimer’s disease. However, it is difficult in humans to establish when these deficits appear and their impact in the course of Alzheimer’s disease. In the TgF344-Alzheimer’s disease rat model at the age of 6 months, we showed a reduction in in vivo release of striatal dopamine due to serotonin 5HT_2A-receptor blockade, in the absence of alterations in 5HT_2A-receptor binding, suggesting a reduction in 5HT_2A-receptor-dopamine system connectivity. In addition, a functional hypersensitivity of postsynaptic dopamine D₂-receptors and D₂-autoreceptors was also reported without any change in D₂-receptor density and in the absence of amyloid plaques or overexpression of the 18 kDa translocator protein (an inflammatory marker) in areas of the dopamine system. Citalopram, a selective serotonin reuptake inhibitor, induced functional 5HT_2A-receptor−D₂-receptor connectivity changes but had no effect on D₂-autoreceptor hypersensitivity. In older rats, dopamine cell bodies overexpressed translocator protein and dopamine projection sites accumulated amyloid. Interestingly, the 5HT_2A-receptor density is decreased in the accumbens subdivisions and the substantia nigra pars compacta. This reduction in the striatum is related to the astrocytic expression of 5HT_2A-receptor. Our results indicate that both serotonin/dopamine connectivity and dopamine signalling pathways are dysregulated and potentially represent novel early diagnostic and therapeutic avenues.

Diagnosis of Mild Cognitive Impairment Using Cognitive Tasks: A Functional Near-Infrared Spectroscopy Study

BACKGROUND

Early diagnosis of Alzheimer's disease (AD) is essential in preventing its progression to dementia. Mild cognitive impairment (MCI) can be indicative of early-stage AD. In this study, we propose a channel-wise feature extraction method of functional near-infrared spectroscopy (fNIRS) data to diagnose MCI when performing cognitive tasks, including two-back, Stroop, and semantic verbal fluency tasks (SVFT).

METHODS

A new channel-wise feature extraction method is proposed as follows: A region-of-interest (ROI) channel is defined as such channel having a statistical difference (p < 0.05) in t-values between two groups. For each ROI channel, features (the mean, slope, skewness, kurtosis, and peak value of oxy- and deoxy-hemoglobin) are extracted. The extracted features for the two classes (MCI, HC) are classified using the linear discriminant analysis (LDA) and support vector machine (SVM). Finally, the classifiers are validated using the area under curve (AUC) of the receiver operating characteristics. Furthermore, the suggested feature extraction method is compared with the conventional approach. Fifteen MCI patients and fifteen healthy controls (HCs) participated in the study.

RESULTS

In the two-back and Stroop tasks, HCs showed activation in the ventrolateral prefrontal cortex (VLPFC). However, in the case of MCI, the VLPFC was not activated. Instead, Ch. 30 was activated. In the SVFT task, the PFC was activated in both groups, but the t-values of HCs were higher than those of MCI. For the SVFT, the classification accuracies using the proposed feature extraction method were 80.77% (LDA) and 83.33% (SVM), showing the highest among the three tasks; for the Stroop task, 79.49% (LDA) and 73.08% (SVM); and for the two-back task, 73.08% (LDA) and 69.23% (SVM).

CONCLUSION

The cognitive disparities between the MCI and HC groups were detected in the ventrolateral prefrontal cortex using fNIRS. The proposed feature extraction method has shown an improvement in the classification accuracies, see Subsection 3.3. Most of all, the suggested method contains a groupdistinction information per cognitive task. The obtained results successfully discriminated MCI patients from HCs, which reflects that the proposed method is an efficient tool to extract features in fNIRS signals.

Working Memory Training in Amnestic and Non-amnestic Patients With Mild Cognitive Impairment: Preliminary Findings From Genotype Variants on Training Effects

Working memory training (WMT) effects may be modulated by mild cognitive impairment (MCI) subtypes, and variations in APOE-epsilon (APOE-ε) and LMX1A genotypes. Sixty-one individuals (41 men/20 women, mean age 66 years) diagnosed with MCI (31 amnestic/30 non-amnestic) and genotyped for APOE-ε and LMX1A completed 4 weeks/20-25 sessions of WMT. Cognitive functions were assessed before, 4 weeks and 16 weeks after WMT. Except for Processing Speed, the non-amnestic MCI group (naMCI) outperformed the amnestic MCI (aMCI) group in all cognitive domains across all time-points. At 4 weeks, working memory function improved in both groups (p < 0.0001), but at 16 weeks the effects only remained in the naMCI group. Better performance was found after training for the naMCI patients with LMX1A-AA genotype and for the APOE-ε4 carriers. Only the naMCI-APOE-ε4 group showed improved Executive Function at 16 weeks. WMT improved working memory and some non-trained cognitive functions in individuals with MCI. The naMCI group had greater training gain than aMCI group, especially in those with LMX1A-AA genotype and among APOE-ε4-carriers. Further research with larger sample sizes for the subgroups and longer follow-up evaluations is warranted.

Different patterns of β-amyloid deposition in patients with Alzheimer's disease according to the presence of mild parkinsonism

This study aimed to compare the patterns of β-amyloid deposition between patients with early-stage Alzheimer's disease (AD) with mild parkinsonism and those without parkinsonism. Sixty-one patients with early-stage AD (Clinical Dementia Rating [CDR], 0.5 or 1) who underwent ¹⁸F-florbetaben (¹⁸F-FBB) PET scans were enrolled. We performed comparative analyses of regional FBB uptake in the frontal, parietal, lateral temporal, medial temporal, occipital, anterior cingulate, and posterior cingulate cortices and in the precuneus, striatum, and thalamus between AD patients with mild parkinsonism (AD-p+; n = 23) and those without parkinsonism (AD-p-; n = 38). There was no significant difference in age, sex, years of education, Mini-Mental State Examination score, and white matter hyperintensity severity between groups. The AD-p+ group had lower composite scores in frontal/executive function domain than the AD-p- group. The AD-p+ group had a higher FBB uptake in the occipital cortex, but not in other cortical regions, than the AD-p- group. Our findings suggest that additional β-amyloid deposition in the occipital region is associated with mild parkinsonism in early-stage AD.

A comparison of the prevalence of Fear of Falling between older patients with Lewy body dementia, Alzheimer's disease, and without dementia

BACKGROUND

The development of cognitive impairment and Fear of Falling (FoF) are strongly linked, but prevalence of FoF is not known in patients with different types of dementia. This study aims to evaluate and compare the prevalence and severity of FoF in patients' with dementia with Lewy bodies (DLB), Alzheimer disease (AD), and non-dementia.

METHODS

46 participants with DLB, 86 participants with AD and participants without dementia (controls), underwent Comprehensive Geriatric Assessment (CGA). The Falls Efficacy Scale-International (FES-I) was used to determine and classify FoF. An overall score on the FES-I of 16-19, 20-27 and ≥28, was accepted as low, moderate, and high concern about FoF, respectively.

RESULTS

Prevalence of high FoF was 86.9% in DLB, 36.0% in AD and 37.4% in controls. All CGA parameters were worse in the DLB and AD group than non-dementia group (p < 0.001). The prevalence of high FoF/FES-scores was significantly higher in the DLB group than in the AD and non-dementia group (p < 0.001), but was similar in AD and non-dementia groups (p > 0.05). The significant relationship between DLB and FoF was maintained when adjusted for age, CGA parameters, and orthostatic hypotension (OR: 2.55, CI: 1.03-6.25, p = 0.041 comparison to AD; OR: 4.79, CI: 2.10-10.92, p < 0.001 comparison to non-dementia).

CONCLUSION

Eight out of ten elderly patients with DLB have high FoF, which is much higher than those with AD and without dementia. Therefore, clinicians should be aware of FoF and its related consequences in the management of DLB in older adults.

Spatial reference learning deficits in absence of dysfunctional working memory in the TgF344-AD rat model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by cognitive disorders and alterations of behavioral traits such as anhedonia and anxiety. Contribution of nonphysiological forms of amyloid and tau peptides to the onset of neurological dysfunctions remains unclear because most preclinical models only present one of those pathological AD-related biomarkers. A more recently developed model, the TgF344-AD rat has the advantage of overexpressing amyloid and naturally developing tauopathy, thus making it close to human familial forms of AD. We showed the presence of a learning dysfunction in a reference memory test, without spatial working memory impairment but with an increase in anxiety levels and a decrease in motivation to participate in the test. In the sucrose preference test, TgF344-AD rats did not show signs of anhedonia but did not increase the volume of liquid consumed when the water was replaced by sucrose solution. These behavioral phenomena were observed at an age when tau accumulation are absent, and where amyloid deposits are predominant in the hippocampus and the entorhinal cortex. Within the hippocampus itself, amyloid accumulation is heterogenous between the subiculum, the dorsal hippocampus and the ventral hippocampus. Thus, our data demonstrated heterogeneity in the appearance of various behavioral and neurochemical markers in the TgF344-AD rat. This multivariate analysis will therefore make it possible to define the stage of the pathology, to measure its evolution and the effects of future therapeutic treatments.

Association Between Olfactory Impairment and Disease Severity and Duration in Parkinson's Disease

Background

The association between olfactory dysfunction and disease duration and severity in Parkinson's disease (PD) remains controversial.

Objective

The objective of this study was to examine the relationship between olfactory dysfunction and disease severity and duration in patients with recently diagnosed parkinsonism and patients with PD with a previous diagnosis.

Methods

Olfactory function was evaluated in 79 patients with recently diagnosed parkinsonism, 71 patients with PD with a previous diagnosis-with patients in both groups free of cognitive impairment-and 128 age-matched controls. The Odor-Stick Identification Test for Japanese score was counted as the numbers of correct answers, responses of indistinguishable, and responses of odorless. Parkinsonism was evaluated using the Movement Disorder Society Criteria, the Unified Parkinson Disease Rating Scale (UPDRS) Part III, and ¹²³iodine-labeled N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl) nortropane single photon emission computed tomography (DaTscan).

Results

In the patients with recently diagnosed parkinsonism having the UPDRS Part III score ≥5 (mean [standard deviation: SD] score: 6.3 [1.9]) and with a positive DaTscan, the mean (SD) numbers of correct answers, responses of indistinguishable and responses of odorless were 4.3 (2.2), 1.6 (2.0), and 1.2 (2.2), respectively. In patients with PD with a previous diagnosis (mean [SD] UPDRS Part III score: 10.9 [3.2]), these numbers were 2.5 (2.2), 2.2 (2.5), and 3.8 (4.6), respectively. The patients with PD with a previous diagnosis showed more significant deterioration than the patients with recently diagnosed parkinsonism in the numbers of correct answers and responses of odorless (P < 0.0001). Olfaction in the combined patient group was significantly impaired compared with age-matched controls in each category (P < 0.0001).

Conclusions

These findings imply a close association between olfactory dysfunction and disease severity and duration in PD.

Presynaptic dopaminergic function in early-onset Alzheimer's disease: an FP-CIT image study

We aimed to investigate whether amyloid-β (Aβ) positive early-onset Alzheimer's disease (EOAD) patients have presynaptic dopaminergic deficits on in vivo ¹⁸F-FP-CIT PET imaging. We enrolled 34 EOAD patients and 9 cognitively normal controls (NC), all of whom underwent ¹⁸F-florbetaben and ¹⁸F-FP-CIT PET at Samsung Medical Center. We assessed motor symptoms using Unified Parkinson's Disease Rating Scale (UPDRS) and divided the EOAD patients into 2 groups using a UPDRS cutoff of 10. We compared regional florbetaben and FP-CIT uptake across the NC and the 2 EOAD groups with lower and higher UPDRS and investigated the associations between regional florbetaben or FP-CIT uptake and UPDRS in EOAD patients. Among the 30 EOAD patients who were Aβ positive on florbetaben PET, the higher UPDRS (>10) group (n = 9) had a longer disease duration (7.2 ± 3.3 vs. 4.1 ± 1.8, p = 0.002), and had a tendency to have lower Mini-Mental State Examination (9.6 ± 7.9 vs. 15.0 ± 6.0, p = 0.052) than the lower UPDRS (≤10) group (n = 21). Across the NC and the 2 EOAD groups, there were no significant differences in FP-CIT uptake in caudate (p = 0.122) and putamen (p = 0.685) or florbetaben uptake in midbrain (p = 0.890). Finally, regression analyses showed that UPDRS was not associated with FP-CIT uptake in caudate (p = 0.913) or putamen (p = 0.407), or with florbetaben PET uptake in caudate (p = 0.553), putamen (p = 0.617), midbrain (p = 0.843), or global cortex (p = 0.658). This study showed that parkinsonian signs in EOAD patients may be related with mechanisms other than presynaptic dopaminergic deficit. Our finding is clinically important because it suggests that L-dopa treatment in EOAD with parkinsonian signs may not improve motor symptoms.