Neuropathological correlates of neuropsychiatric symptoms in dementia

Plasma phosphorylated tau and neuropsychiatric symptoms in dementia with Lewy bodies

INTRODUCTION

Neuropsychiatric symptoms (NPSs) are common in dementia with Lewy bodies (DLB) but their neurobiological mechanisms are poorly understood.

METHODS

NPSs and cognition were assessed annually in participants (DLB n = 222; Alzheimer's disease [AD] n = 125) from the European DLB (E-DLB) Consortium, and plasma phosphorylated tau-181 (p-tau181) and p-tau231 concentrations were measured at baseline.

RESULTS

Hallucinations, delusions, and depression were more common in DLB than in AD and, in a subgroup with longitudinal follow-up, persistent hallucinations and NPSs were associated with lower p-tau181 and p-tau231 in DLB. In adjusted linear mixed-effects models, hallucinations at baseline were associated with greater longitudinal cognitive impairment in DLB, with a significant interaction with p-tau231.

DISCUSSION

Higher p-tau181 and p-tau231 levels were associated with a lower longitudinal risk of NPSs and hallucinations in early-stage DLB. However, the interaction between hallucinations and p-tau231 suggests that when AD co-pathology and hallucinations do co-exist in DLB that they may synergistically exacerbate cognitive decline.

HIGHLIGHTS

Neuropsychiatric symptoms (NPSs) were more common in dementia with Lewy bodies (DLB) than in Alzheimer's disease (AD). Lower plasma phosphorylated tau-231 (p-tau231) and p-tau181 levels were associated with persistent hallucinations in DLB. Lower plasma p-tau231 and p-tau181 levels were associated with an increased risk of persistent NPSs in early DLB. Hallucinations at baseline were associated with greater cognitive dysfunction in DLB, and there was an interaction with p-tau231.

Investigating neuropathological correlates of hyperactive and psychotic symptoms in dementia: a systematic review

Introduction

Behavioral and Psychological Symptoms of Dementia (BPSD) are common neuropsychiatric manifestations that complicate the clinical course of dementia and impact caregiving. Among these, the Hyperactivity-Impulsivity-Irritiability-Disinhibition-Aggression-Agitation (HIDA) and Psychosis (P) domains are particularly challenging to manage. Despite their prevalence, their underlying mechanisms and neuropathological correlates, remain poorly understood. This systematic review aims to elucidate the neuropathological basis of the HIDA and psychosis domains, exploring whether distinct proteinopathies and neural circuit dysfunctions are associated with these symptoms.

Methods

The review follows PRISMA guidelines, with a systematic search conducted across MEDLINE, CENTRAL, and EMBASE databases. Inclusion criteria involved studies exploring the neuropathology of the HIDA and psychosis domains in individuals with dementia. Records were screened using PICO software, and data quality was assessed using the Newcastle-Ottawa Scale (NOS) and CARE guidelines. A narrative synthesis was conducted due to heterogeneity in the data.

Results

From 846 records identified, 37 studies met inclusion criteria. Of the 18,823 cases analyzed, the most common diagnoses were Alzheimer's Disease (83.44%), Dementia with Lewy Bodies (5.37%), and Frontotemporal Dementia (13.40%). HIDA-P symptoms were distributed across all clinical diagnoses, with agitation (14.00%), delusions (11.60%), disinhibition (7.61%), and hallucinations (6.83%) being the most frequently reported behaviors. The primary neuropathological diagnosis was Alzheimer's Disease Neuropathologic Change (ADNC), present predominantly in intermediate to severe forms. The neuropathological analysis revealed the co-occurrence of multiple proteinopathies, particularly TAUopathy, TDP-43 pathology, and Lewy-related pathology (LRP), with the latter, in association with ADNC, reported in 15 studies.

Discussion

HIDA-P symptoms were linked with overlapping involvement of different neural circuits, particularly the amygdala and the broader limbic system. Evidence suggests that TAUopathy and multiple proteinopathies in key brain regions, such as amygdala, are central to the development of these symptoms. In contrast, the contribution of beta-amyloid and vascular damage appears marginal in the genesis of HIDA and psychotic symptoms. No behavioral symptom is pathognomonic of a specific proteinopathy; rather, the topography and severity of lesions plays a more decisive role than their single molecular composition.

Systematic review registration

INPLASY2024100082.

The Excess Direct Social Costs of Dementia-Related Neuropsychiatric Symptoms: A Regionwide Cohort Study Beyond Silos

OBJECTIVES

To estimate the excess formal social costs or direct non-healthcare costs of dementia-related neuropsychiatric symptoms (NPS).

METHODS

The presence of dementia, NPS, antipsychotic and antidepressant use, somatic and psychiatric comorbidities, and formal social benefits were studied in a regionwide cohort of all 60-year-old and older individuals. A random forest-based algorithm identified NPS, and 2-part regression models and entropy balance were used.

RESULTS

Of the 215 859 individuals, 7553 (3.50%) had dementia, 74 845 (34.7%) had some NPS, and 20 787 (9.63%) received long-term care benefits. Notably, nearly two-thirds (63.9%) of people with dementia received benefits. The probability of having social costs varied markedly with age (odds ratio [OR] 12.28 [10.17-14.82] for >90-year-olds category), and the presence of dementia (OR 7.36 [6.13-8.84]) or NPS (OR 3.23 [2.69-3.88]). NPS (relative change [RC] 1.39 [1.31-1.49]) and dementia (RC 1.32 [1.24-1.41]) were associated with higher average benefit costs. Low socioeconomic status was significantly associated with both a higher probability of receiving benefits (OR 1.52 [1.38-1.68]) and higher costs of their provision (RC 1.18 [1.15-1.21]).

CONCLUSIONS

The burden of caring for NPS is greater than that indicated by the literature as these symptoms multiply the social costs of dementia by more than 3, owing to the greater use of residential care and formal coverage reaching more patients than that indicated by the literature. The greater presence of dementia and NPS in the population of lower socioeconomic status indicates an inequality in health attenuated by greater use of social benefits.

The neural basis of neuropsychiatric symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) such as depression, anxiety, apathy and aggression affect up to 90% of Alzheimer's disease (AD) patients. These symptoms significantly increase caregiver stress and institutionalization rates, and more importantly they are correlated with faster cognitive decline. However, the neuronal basis of NPS in AD remains largely unknown. Here, we review current understanding of NPS and related pathology in studies of AD patients and AD mouse models. Clinical studies indicate that NPS prevalence and severity vary across different AD stages and types. Neuroimaging and postmortem studies have suggested that pathological changes in the anterior cingulate cortex, hippocampus, prefrontal cortex, and amygdala are linked to NPS, although the precise mechanisms remain unclear. Studies of AD mouse models have indicated that amyloid-beta and tau-related neurodegeneration in the hippocampus, prefrontal cortex, and anterior cingulate cortex are correlated with NPS-like behavioral deficits. A better understanding of the NPS phenotypes and related pathological changes will pave the way for developing a better management strategy for NPS in AD patients.

Neuropsychiatric Symptoms in Dementia

OBJECTIVE

This article discusses the prevalence, pathophysiology, assessment, and management of neuropsychiatric symptoms in patients with dementia.

LATEST DEVELOPMENTS

There is a growing body of evidence localizing neuropsychiatric symptoms in dementia to frontal circuits in the brain, as well as relating them to pathologic changes seen in different dementias. Although very few medications have been approved by the US Food and Drug Administration (FDA) for the treatment of neuropsychiatric symptoms in dementia, there are more clinical trials showing the benefit of antidepressants, stimulants, and antipsychotics. In line with that trend, in 2023, the FDA approved the use of brexpiprazole, an atypical antipsychotic, for the treatment of agitation in Alzheimer disease dementia.

ESSENTIAL POINTS

Neuropsychiatric symptoms are a core feature of all dementias and often emerge before cognitive symptoms manifest. They are highly clinically significant symptoms that disrupt the lives of patients and care partners and greatly influence the decision to place patients in long-term care facilities. The first line of treatment for neuropsychiatric symptoms in dementia is nonpharmacologic behavioral modification, but clinicians often must supplement this intervention with medications using an empiric approach.

Modeling the progression of neuropsychiatric symptoms in Alzheimer's disease with PET-based Braak staging

In Alzheimer's disease (AD), neuropsychiatric symptoms (NPS) correlate with tau deposition in the brain. Here, we investigated the association of PET-based Braak stages with NPS and assessed whether they predict annual changes in NPS. We evaluated 231 individuals in the aging and AD continuum. Participants were assigned a Braak stage at baseline and followed for 1.97 (s.d. 0.62) years. NPS were investigated using the Mild Behavioral Impairment Checklist (MBI-C) and the Neuropsychiatric Inventory Questionnaire severity (NPI-Q-S) and distress (NPI-Q-D) scales. Multiple linear regressions (MLR) assessed the association of Braak stages with baseline NPS and the annual change in NPS scores. At baseline, stages I-II, III-IV, and V-VI were associated with higher MBI-C, NPI-Q-S, and NPI-Q-D scores. Stages V-VI were associated with a significant annual increase in MBI-C scores. These findings suggest that tau accumulation may manifest clinically with an increase in NPS, which seems to be an early event in AD pathophysiology. Moreover, PET-based Braak staging appears to be a good predictor of NPS severity progression.

Neuropsychiatric symptoms and white matter hyperintensities in older adults without dementia

OBJECTIVE

We aimed to examine associations between neuropsychiatric symptoms (NPS) and white matter hyperintensities (WMH) status in older adults without dementia under the hypothesis that WMH increased the odds of having NPS.

DESIGN

Longitudinal analysis of data acquired from the National Alzheimer's Coordinating Center Uniform Data Set.

SETTINGS

Data were derived from 46 National Institute on Aging - funded Alzheimer's Disease Research Centers.

PARTICIPANTS

NACC participants aged ≥50 years with available data on WMH severity with a diagnosis of mild cognitive impairment (MCI) or who were cognitively unimpaired (CU) were studied. Among 4617 CU participants, 376 had moderate and 54 extensive WMH. Among 3170 participants with MCI, 471 had moderate and 88 had extensive WMH.

MEASUREMENTS

Using Cardiovascular Health Study (CHS) scores, WMH were coded as no to mild (CHS score: 0-4), moderate (score: 5-6) or extensive (score: 7-8). NPS were quantified on the Neuropsychiatric Inventory Questionnaire. Binary logistic regression models estimated the odds of reporting each of 12 NPS by WMH status separately for individuals with MCI or who were CU.

RESULTS

Compared to CU individuals with no to mild WMH, the odds of having elation [9.87, (2.63-37.10)], disinhibition [4.42, (1.28-15.32)], agitation [3.51, (1.29-9.54)] or anxiety [2.74, (1.28-5.88)] were higher for the extensive WMH group, whereas the odds of having disinhibition were higher for the moderate WMH group [1.94, (1.05-3.61)]. In the MCI group, he odds of NPS did not vary by WMH status.

CONCLUSIONS

Extensive WMH were associated with higher odds of NPS in CU older adults but not in those with MCI.

Subsyndromes and symptom clusters: Multilevel factor analysis of behavioral and psychological symptoms of dementia with intensive longitudinal data

INTRODUCTION

Behavioral and psychological symptoms in dementia (BPSD) are dynamic phenomena with a high amount of intraindividual variability. We applied a multilevel framework to identify subsyndromes (between-person factors) that represent clinically relevant profiles of BPSD and identify symptom clusters (within-person factors) that represent contextually driven daily symptom experiences.

METHODS

This study used an intensive longitudinal design in which 68 co-residing family caregivers to persons living with dementia were recruited to proxy report on their care recipient's daily symptom experiences of 23 different BPSD for eight consecutive days (n = 443 diaries). A multilevel exploratory/confirmatory factor analysis was used to account for nested data and separate within-person variances from between-level factor estimates.

RESULTS

Exploratory factor analysis identified a 4-between 3-within factor structure based on fit statistics and clinical interpretability.

DISCUSSION

This study offers major methodological and conceptual advancements for management of BPSD within Alzheimer's disease and related dementias by introducing two related but distinct concepts of subsyndromes and symptom clusters.

HIGHLIGHTS

Because behavioral and psychological symptoms of dementia (BPSD) are dynamic temporal phenomenon, this introduces measurement error into aggregate group-level estimates when trying to create subsyndromes. We propose a multilevel analysis to provide a more valid and reliable estimation by separating out variance due to within-person daily fluctuations. Using a multilevel exploratory factor analysis with intensive longitudinal data, we identified distinct and meaningful groups of BPSD. The four factors at the between-person level represented subsyndromes that are based on how BPSD co-occurred among persons with Alzheimer's disease (AD). These subsyndromes are clinically relevant because they share features of established clinical phenomena and may have similar neurobiological etiologies. We also found three within-person factors representing distinct symptom clusters. They are based on how BPSD clustered together on a given day for an individual with AD and related dementias. These clusters may have shared environmental triggers.

Associations Between Neuropsychiatric Symptoms and Inflammation in Neurodegenerative Dementia: A Systematic Review

Background

Neuropsychiatric symptoms are common in dementia and linked to adverse outcomes. Inflammation is increasingly recognized as playing a role as a driver of early disease progression in Alzheimer's disease (AD) and related dementias. Inflammation has also been linked to primary psychiatric disorders, however its association with neuropsychiatric symptoms in neurodegenerative dementias remains uncertain.

Methods

We conducted a systematic literature review investigating associations between inflammation and neuropsychiatric symptoms in neurodegenerative dementias, including AD, Lewy body, Frontotemporal, Parkinson's (PD) and Huntington's disease dementias.

Results

Ninety-nine studies met our inclusion criteria, and the majority (n = 59) investigated AD and/or mild cognitive impairment (MCI). Thirty-five studies included PD, and only 6 investigated non-AD dementias. Inflammation was measured in blood, CSF, by genotype, brain tissue and PET imaging. Overall, studies exhibited considerable heterogeneity and evidence for specific inflammatory markers was inconsistent, with lack of replication and few longitudinal studies with repeat biomarkers. Depression was the most frequently investigated symptom. In AD, some studies reported increases in peripheral IL-6, TNF-a associated with depressive symptoms. Preliminary investigations using PET measures of microglial activation found an association with agitation. In PD, studies reported positive associations between TNF-a, IL-6, CRP, MCP-1, IL-10 and depression.

Conclusion

Central and peripheral inflammation may play a role in neuropsychiatric symptoms in neurodegenerative dementias; however, the evidence is inconsistent. There is a need for multi-site longitudinal studies with detailed assessments of neuropsychiatric symptoms combined with replicable peripheral and central markers of inflammation.

Evaluating the Effect of Alzheimer's Disease-Related Biomarker Change in Corticobasal Syndrome and Progressive Supranuclear Palsy

OBJECTIVES

To evaluate the effect of Alzheimer's disease (AD) -related biomarker change on clinical features, brain atrophy and functional connectivity of patients with corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP).

METHODS

Data from patients with a clinical diagnosis of CBS, PSP, and AD and healthy controls were obtained from the 4-R-Tauopathy Neuroimaging Initiative 1 and 2, the Alzheimer's Disease Neuroimaging Initiative, and a local cohort from the Toronto Western Hospital. Patients with CBS and PSP were divided into AD-positive (CBS/PSP-AD) and AD-negative (CBS/PSP-noAD) groups based on fluid biomarkers and amyloid PET scans. Cognitive, motor, and depression scores; AD fluid biomarkers (cerebrospinal p-tau, t-tau, and amyloid-beta, and plasma ptau-217); and neuroimaging data (amyloid PET, MRI and fMRI) were collected. Clinical features, whole-brain gray matter volume and functional networks connectivity were compared across groups.

RESULTS

Data were analyzed from 87 CBS/PSP-noAD and 23 CBS/PSP-AD, 18 AD, and 30 healthy controls. CBS/PSP-noAD showed worse performance in comparison to CBS/PSP-AD in the PSPRS [mean(SD): 34.8(15.8) vs 23.3(11.6)] and the UPDRS scores [mean(SD): 34.2(17.0) vs 21.8(13.3)]. CBS/PSP-AD demonstrated atrophy in AD signature areas and brainstem, while CBS/PSP-noAD patients displayed atrophy in frontal and temporal areas, globus pallidus, and brainstem compared to healthy controls. The default mode network showed greatest disconnection in CBS/PSP-AD compared with CBS/PSP-no AD and controls. The thalamic network connectivity was most affected in CBS/PSP-noAD.

INTERPRETATION

AD biomarker positivity may modulate the clinical presentation of CBS/PSP, with evidence of distinctive structural and functional brain changes associated with the AD pathology/co-pathology. ANN NEUROL 2024;96:99-109.

The Relationship Between First Presenting Neuropsychiatric Symptoms in Older Adults and Autopsy-Confirmed Memory Disorders

OBJECTIVES

Although dementia is typically considered a disease of cognitive decline, almost all patients present with neuropsychiatric symptoms (NPS) at some stage of their disease. Few studies have assessed the timing of NPS onset in relation to pathological diagnoses of neurodegenerative diseases. We sought to examine the association between the first presenting clinically significant NPS in aging individuals and neuropathological diagnoses of memory disorders.

DESIGN

This retrospective longitudinal cohort study utilized the National Alzheimer's Coordinating Center (NACC) dataset, which includes participant data from 37 Alzheimer's Disease Research Centers collected between 2005 and 2022.

PARTICIPANTS

Participants (N = 5,416) aged 45 years or older with Clinical Dementia Rating-Global ratings of less than or equal to 1 were included in this analysis. A total of 4,033 (74.5%) participants presented with at least one NPS at any NACC visit.

MEASUREMENTS

To measure first NPS, the NACCBEHF variable was used, a clinician-rated variable defined as "the predominant symptom that was first recognized as a decline in the subject's behavior." Neuropathologic variables included assessments of Alzheimer's Disease, Frontotemporal Dementia, Lewy Body Dementia, Cerebral Amyloid Angiopathy, Hippocampal Sclerosis, and Cerebrovascular Disease.

RESULTS

Presentation with any clinically significant first NPS was associated with several neuropathological diagnoses including Alzheimer's Disease, Frontotemporal Lobar Dementia with TDP-43 pathology, and Lewy Body Dementia. While specific first NPS were associated with Frontotemporal Dementia neuropathology (personality change and disinhibition) and Lewy Body Dementia neuropathology (psychosis and REM behavior disturbance), Alzheimer's Disease neuropathology was associated with the majority of NPS.

CONCLUSIONS

Since neuropsychiatric symptoms are frequently the first presenting symptom of dementia, their associations with well-defined neuropathological diagnoses may help clinicians predict the subtype of future dementias.

Tau in dementia with Lewy bodies

OBJECTIVE

Neurofibrillary tangles are present in a proportion of people with dementia with Lewy bodies and may be associated with worse cognition. Recent advances in biomarkers for Alzheimer's disease include second-generation tau positron emission tomography as well as the detection of phosphorylated tau at threonine 181 (p-tau181) in plasma. This study aimed to investigate tau in people with dementia with Lewy bodies using a second-generation tau positron emission tomography tracer as well as plasma p-tau181.

METHODS

Twenty-seven participants (mean age 74.7 ± 5.5) with clinically diagnosed probable dementia with Lewy bodies underwent comprehensive clinical assessment and positron emission tomography imaging (18F-MK6240 and 18F-NAV4694). Plasma p-tau181 levels were measured using Simoa technology.

RESULTS

Five dementia with Lewy bodies participants (18.5%) had an abnormal tau positron emission tomography (increased tau uptake in the temporal meta-region-of-interest). Higher plasma p-tau181 concentrations correlated with higher tau deposition in the temporal region (ρ = 0.46, 95% confidence interval = [0.10, 0.72]) and classified abnormal tau positron emission tomography in dementia with Lewy bodies with an area under the curve of 0.95 (95% confidence interval = [0.86, 0.99]). Plasma p-tau181 also correlated positively with cortical amyloid-beta binding (ρ = 0.68, 95% confidence interval = [0.40, 0.84]) and classified abnormal amyloid-beta positron emission tomography in dementia with Lewy bodies with an area under the curve of 0.91 (95% confidence interval = [0.79, 0.99]). There was no association found between tau deposition and any of the clinical variables.

CONCLUSIONS

Tau is a common co-pathology in dementia with Lewy bodies. Plasma p-tau181 correlated with abnormal tau and amyloid-beta positron emission tomography and may potentially be used as a marker to identify co-morbid Alzheimer's disease-related pathology in dementia with Lewy bodies. The clinical implications of tau in dementia with Lewy bodies need to be further evaluated in larger longitudinal studies.

Hippocampal sclerosis of aging at post-mortem is evident on MRI more than a decade prior

INTRODUCTION

Hippocampal sclerosis of aging (HS) is an important component of combined dementia neuropathology. However, the temporal evolution of its histologically-defined features is unknown. We investigated pre-mortem longitudinal hippocampal atrophy associated with HS, as well as with other dementia-associated pathologies.

METHODS

We analyzed hippocampal volumes from magnetic resonance imaging (MRI) segmentations in 64 dementia patients with longitudinal MRI follow-up and post-mortem neuropathological evaluation, including HS assessment in the hippocampal head and body.

RESULTS

Significant HS-associated hippocampal volume changes were observed throughout the evaluated timespan, up to 11.75 years before death. These changes were independent of age and Alzheimer's disease (AD) neuropathology and were driven specifically by CA1 and subiculum atrophy. AD pathology, but not HS, was associated significantly with the rate of hippocampal atrophy.

DISCUSSION

HS-associated volume changes are detectable on MRI earlier than 10 years before death. Based on these findings, volumetric cutoffs could be derived for in vivo differentiation between HS and AD.

HIGHLIGHTS

Hippocampal atrophy was found in HS+ patients earlier than 10 years before death. These early pre-mortem changes were driven by reduced CA1 and subiculum volumes. Rates of hippocampus and subfield volume decline were independent of HS. In contrast, steeper atrophy rates were associated with AD pathology burden. Differentiation between AD and HS could be facilitated based on these MRI findings.

Alzheimer's Type Neuropathological Changes in a Patient with Depression and Anxiety: A Case Report and Literature Review of Neuropathological Correlates of Neuropsychiatric Symptoms in Alzheimer's Disease

Alzheimer's disease (AD) is classified as a tauopathy and is the most common neuropathological correlate of dementia/cognitive impairment. AD is neuropathologically characterized by the presence of beta-amyloid immunoreactive senile plaques and tau positive neurofibrillary tangles. Neuropsychiatric symptoms of AD however continue to be underscored, and therefore, neuropathological correlates of these neuropsychiatric symptoms are not readily studied. Presented here is a case of 60-year-old female who initially presented with anxiety and depression, and continued to be the predominant symptoms although mild cognitive impairment was noted as per the available clinical notes. Postmortem examination of the brain revealed severe Alzheimer's type neuropathological changes, which included significant tau and beta-amyloid pathology in limbic regions, which were thought to represent correlates of the patient's depression and anxiety. This case report illustrates the possible neuropathological correlates of neuropsychiatric symptoms in patients with AD. The author hopes that such a case will promote more in-depth studies into the pathophysiology of neuropsychiatric manifestations in AD.

Depression in dementia with Lewy bodies: a critical update

Depression with an estimated prevalence of 35% is a frequent manifestation of dementia with Lewy bodies (DLB), having negative effects on cognitive performance and life expectancy, yet the underlying neurobiology is poorly understood and most likely heterogeneous. Depressive symptoms in DLB can occur during the clinical course and, together with apathy, is a common prodromal neuropsychiatric symptom of this neurocognitive disorder in the group of Lewy body synucleinopathies. There are no essential differences in the frequency of depression in DLB and Parkinson disease-dementia (PDD), while its severity is up to twice as high as in Alzheimer disease (AD). Depression in DLB that is frequently underdiagnosed and undertreated, has been related to a variety of pathogenic mechanisms associated with the basic neurodegenerative process, in particular dysfunctions of neurotransmitter systems (decreased monoaminergic/serotonergic, noradrenergic and dopaminergic metabolism), α-synuclein pathology, synaptic zinc dysregulation, proteasome inhibition, gray matter volume loss in prefrontal and temporal areas as well as dysfunction of neuronal circuits with decreased functional connectivity of specific brain networks. Pharmacotherapy should avoid tricyclic antidepressants (anticholinergic adverse effects), second-generation antidepressants being a better choice, while modified electroconvulsive therapy, transcranial magnetic stimulation therapy and deep brain stimulation may be effective for pharmacotherapy-resistant cases. Since compared to depression in other dementias like Alzheimer disease and other parkinsonian syndromes, our knowledge of its molecular basis is limited, and further studies to elucidate the heterogeneous pathogenesis of depression in DLB are warranted.

An Update on Apathy in Alzheimer's Disease

Apathy is a complex multi-dimensional syndrome that affects up to 70% of individuals with Alzheimer's disease (AD). Whilst many frameworks to define apathy in AD exist, most include loss of motivation or goal-directed behaviour as the central feature. Apathy is associated with significant impact on persons living with AD and their caregivers and is also associated with accelerated cognitive decline across the AD spectrum. Neuroimaging studies have highlighted a key role of fronto-striatial circuitry including the anterior cingulate cortex (ACC), orbito-frontal cortex (OFC) and associated subcortical structures. Importantly, the presence and severity of apathy strongly correlates with AD stage and neuropathological biomarkers of amyloid and tau pathology. Following from neurochemistry studies demonstrating a central role of biogenic amine neurotransmission in apathy syndrome in AD, recent clinical trial data suggest that apathy symptoms may improve following treatment with agents such as methylphenidate-which may have an important role alongside emerging non-pharmacological treatment strategies. Here, we review the diagnostic criteria, rating scales, prevalence, and risk factors for apathy in AD. The underlying neurobiology, neuropsychology and associated neuroimaging findings are reviewed in detail. Finally, we discuss current treatment approaches and strategies aimed at targeting apathy syndrome in AD, highlighting areas for future research and clinical trials in patient cohorts.

Prediction of neuropathologic lesions from clinical data

INTRODUCTION

Post-mortem analysis provides definitive diagnoses of neurodegenerative diseases; however, only a few can be diagnosed during life.

METHODS

This study employed statistical tools and machine learning to predict 17 neuropathologic lesions from a cohort of 6518 individuals using 381 clinical features (Table S1). The multisite data allowed validation of the model's robustness by splitting train/test sets by clinical sites. A similar study was performed for predicting Alzheimer's disease (AD) neuropathologic change without specific comorbidities.

RESULTS

Prediction results show high performance for certain lesions that match or exceed that of research annotation. Neurodegenerative comorbidities in addition to AD neuropathologic change resulted in compounded, but disproportionate, effects across cognitive domains as the comorbidity number increased.

DISCUSSION

Certain clinical features could be strongly associated with multiple neurodegenerative diseases, others were lesion-specific, and some were divergent between lesions. Our approach could benefit clinical research, and genetic and biomarker research by enriching cohorts for desired lesions.

Neurodegenerative pathologies associated with behavioral and psychological symptoms of dementia in a community-based autopsy cohort

In addition to the memory disorders and global cognitive impairment that accompany neurodegenerative diseases, behavioral and psychological symptoms of dementia (BPSD) commonly impair quality of life and complicate clinical management. To investigate clinical-pathological correlations of BPSD, we analyzed data from autopsied participants from the community-based University of Kentucky Alzheimer's Disease Research Center longitudinal cohort (n = 368 research volunteers met inclusion criteria, average age at death 85.4 years). Data assessing BPSD were obtained approximately annually, including parameters for agitation, anxiety, apathy, appetite problems, delusions, depression, disinhibition, hallucinations, motor disturbance, and irritability. Each BPSD was scored on a severity scale (0-3) via the Neuropsychiatric Inventory Questionnaire (NPI-Q). Further, Clinical Dementia Rating (CDR)-Global and -Language evaluations (also scored on 0-3 scales) were used to indicate the degree of global cognitive and language impairment. The NPI-Q and CDR ratings were correlated with neuropathology findings at autopsy: Alzheimer's disease neuropathological changes (ADNC), neocortical and amygdala-only Lewy bodies (LBs), limbic predominant age-related TDP-43 encephalopathy neuropathologic changes (LATE-NC), primary age-related tauopathy (PART), hippocampal sclerosis, and cerebrovascular pathologies. Combinations of pathologies included the quadruple misfolding proteinopathy (QMP) phenotype with co-occurring ADNC, neocortical LBs, and LATE-NC. Statistical models were used to estimate the associations between BPSD subtypes and pathologic patterns. Individuals with severe ADNC (particularly those with Braak NFT stage VI) had more BPSD, and the QMP phenotype was associated with the highest mean number of BPSD symptoms: > 8 different BPSD subtypes per individual. Disinhibition and language problems were common in persons with severe ADNC but were not specific to any pathology. "Pure" LATE-NC was associated with global cognitive impairment, apathy, and motor disturbance, but again, these were not specific associations. In summary, Braak NFT stage VI ADNC was strongly associated with BPSD, but no tested BPSD subtype was a robust indicator of any particular "pure" or mixed pathological combination.

Hippocampal sclerosis of aging at post-mortem is evident on MRI more than a decade prior

INTRODUCTION

Hippocampal sclerosis of aging (HS) is an important component of combined dementia neuropathology. However, the temporal evolution of its histologically-defined features is unknown. We investigated pre-mortem longitudinal hippocampal atrophy associated with HS, as well as with other dementia-associated pathologies.

METHODS

We analyzed hippocampal volumes from MRI segmentations in 64 dementia patients with longitudinal MRI follow-up and post-mortem neuropathological evaluation, including HS assessment in the hippocampal head and body.

RESULTS

Significant HS-associated hippocampal volume changes were observed thoughout the evaluated timespan, up to 11.75 years before death. These changes were independent of age and Alzheimer’s Disease (AD) burden, and specifically driven by CA1 and subiculum. AD burden, but not HS, significantly associated with the rate of hippocampal atrophy.

DISCUSSION

HS-associated volume changes are detectable on MRI earlier than 10 years before death. These findings could contribute to the derivation of volumetric cut-offs for in vivo differentiation between HS and AD.

Determinants of approved acetylcholinesterase inhibitor response outcomes in Alzheimer's disease: relevance for precision medicine in neurodegenerative diseases

Acetylcholinesterase inhibitors (ChEI) are the global standard of care for the symptomatic treatment of Alzheimer's disease (AD) and show significant positive effects in neurodegenerative diseases with cognitive and behavioral symptoms. Although experimental and large-scale clinical evidence indicates the potential long-term efficacy of ChEI, primary outcomes are generally heterogeneous across outpatient clinics and regional healthcare systems. Sub-optimal dosing or slow tapering, heterogeneous guidelines about the timing for therapy initiation (prodromal versus dementia stages), healthcare providers' ambivalence to treatment, lack of disease awareness, delayed medical consultation, prescription of ChEI in non-AD cognitive disorders, contribute to the negative outcomes. We present an evidence-based overview of determinants, spanning genetic, molecular, and large-scale networks, involved in the response to ChEI in patients with AD and other neurodegenerative diseases. A comprehensive understanding of cerebral and retinal cholinergic system dysfunctions along with ChEI response predictors in AD is crucial since disease-modifying therapies will frequently be prescribed in combination with ChEI. Therapeutic algorithms tailored to genetic, biological, clinical (endo)phenotypes, and disease stages will help leverage inter-drug synergy and attain optimal combined response outcomes, in line with the precision medicine model.

Persistent depressive symptoms are associated with frontal regional atrophy in patients with Alzheimer's disease

BACKGROUND

Depression in individuals with Alzheimer's disease (AD) is common, difficult to treat and inadequately understood. Previous studies have identified possible differences in regional brain atrophy in individuals with AD and depression, but the results have been inconsistent and some studies had less robust definitions of depression. We aimed to examine regional brain atrophy in two large dementia focused cohorts.

METHODS

We used data from Alzheimer's disease neuroimaging initiative (ADNI) and the National Alzheimer's Co-ordinating Center (NACC), for those with data from at least one MRI scan. Depression ratings were available using the Geriatric Depression Scale (GDS) and Neuropsychiatric Inventory (NPI). Intermittent depressive symptoms were defined as one episode above threshold (≥8 on GDS, ≥6 on NPI depression subscale and ≥2 on the Neuropsychiatric Inventory version Q depression sub-scale) and persistent as ≥2 episodes. Derived regional volumetric data was available from ADNI and the NACC.

RESULTS

Data was available from 698 individuals with AD in NACC and from 666 individuals in ADNI. We found no evidence of between group differences in regional brain volume at baseline, or of differential atrophy in NACC. In ADNI we found evidence of increased brain atrophy in several frontal brain areas.

LIMITATIONS

Because this study was limited to those with MRI data, the numbers in some analyses were low. MRI parcellation differed between studies making direct comparison difficult. For some individuals only the NPI was used to rate depression.

CONCLUSIONS

We have found mixed evidence of increased regional atrophy in depression in AD, mainly in frontal brain regions. We found no evidence to support a vascular basis for depression in AD.

Association between behavioral and psychological symptoms and cerebral small vessel disease MRI findings in memory clinic patients

Objectives

Cerebral small vessel disease (SVD) is commonly observed among elderly individuals with cognitive impairment and has been recognized as a vascular contributor to dementia and behavioral and psychological symptoms (BPS), however, the relationship between BPS and SVD burden remains unclear.

Methods

We prospectively recruited 42 patients with mild cognitive impairment (MCI) or mild dementia from the memory clinic in our hospital, who were assigned to either a clinical dementia rating (CDR) of 0.5 or 1.0, respectively. The presence of BPS was determined through interviews with caregivers. The patients underwent brain MRI and three types of SVD scores, total, cerebral amyloid angiopathy (CAA), and modified CAA, were assigned. Patients were also evaluated through various neuropsychological assessments.

Results

The CDR was significantly higher in patients with BPS (p = 0.001). The use of antihypertensive agents was significantly higher in patients without BPS (p = 0.038). The time taken to complete trail making test set-A was also significantly longer in patients with BPS (p = 0.037). There was no significant difference in total SVD and CAA-SVD score (p = 0.745, and 0.096) and the modified CAA-SVD score was significantly higher in patients with BPS (p = 0.046). In addition, the number of total CMBs and lobar CMBs was significantly higher in patients with BPS (p = 0.001 and 0.001). Receiver operating characteristic curves for BPS showed that for modified CAA-SVD, a cutoff score of 3.5 showed 46.7% sensitivity and 81.5% specificity. Meanwhile, for the total number of cerebral microbleeds (CMBs), a cut-off score of 2.5 showed 80.0% sensitivity and 77.8% specificity and for the number of lobar CMBs, a cut-off score of 2.5 showed 73.3% sensitivity and 77.8% specificity.

Conclusion

Overall, patients with BPS showed worse CDRs, reduced psychomotor speed, higher modified CAA-SVD scores, larger numbers of total and lobar CMBs. We propose that severe modified CAA scores and higher numbers of total and lobar CMBs are potential risk factors for BPS in patients with mild dementia or MCI. Therefore, by preventing these MRI lesions, the risk of BPS may be mitigated.