Association Between CSF Beta-Amyloid and Apathy in Early-Stage Alzheimer Disease

Comorbid amyloid with cerebrovascular disease in domain-specific cognitive and neuropsychiatric disturbances: a cross-sectional memory clinic study

Dementia is a multifactorial disorder that is likely influenced by both Alzheimer's disease (AD) and vascular pathologies. We evaluated domain-specific cognitive and neuropsychiatric dysfunction using a two-neuroimaging biomarker construct (beta-amyloid [Aβ] and cerebrovascular disease [CeVD]). We analyzed data from 216 memory clinic participants (mean age = 75.9 ± 6.9; 56.5% female) with neuropsychological and neuropsychiatric assessments, 3T-MRI, and Aβ-PET imaging. Structural equation modeling showed that the largest Aβ (A+) effect was on memory (B = -1.50) and apathy (B = 0.26), whereas CeVD effects were largest on language (B = -1.62) and hyperactivity (B = 0.32). Group comparisons showed that the A+C+ group had greater memory impairment (B = -1.55), hyperactivity (B = 0.79), and apathy (B = 0.74) compared to A-C+; and greater language impairment (B = -1.26) compared to A+C-. These potentially additive effects of Aβ and CeVD burden underline the importance of early detection and treatment of Aβ alongside optimal control of vascular risk factors as a potential strategy in preventing cognitive and neurobehavioral impairment.

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.

Discrepancy Between Patient and Caregiver Estimate of Apathy Predicts Dementia in Patients with Amnestic Mild Cognitive Impairment

BACKGROUND

Apathy is a frequent behavioral symptom of Alzheimer's disease (AD). The Apathy Evaluation Scale (AES) is a tool exploring the perception of apathy by both caregivers (CG-AES) and patients (PT-AES), and the discrepancy in their ratings is a proxy of patients' disease unawareness.

OBJECTIVE

To assess in a cohort study of patients with amnesic mild cognitive impairment (aMCI) whether apathy and awareness of apathy predict progression to dementia and timing.

METHODS

From the global AES scores of 110 patients with aMCI and their caregivers, we obtained two principal indices for analysis: 1) 'Apathy', the mean of PT-AES and CG-AES, and 2) 'Discrepancy', obtained by subtracting CG-AES from PT-AES. Patients were followed with visits every six months for three years or until dementia. AES indices and the principal demographical/neuropsychological variables were filtered from multicollinearity. The most robust variables entered a logistic regression model and survival analyses (Cox regression, log-rank test of Kaplan-Meier curves) to estimate which predicted the risk and timing of progression, respectively.

RESULTS

Sixty patients (54.5%) developed dementia (57 AD) after 6.0-36.0 months, 22 (20%) remained in an MCI stage, and 28 (25.5%) dropped out. 'Discrepancy' was a robust and accurate predictor of the risk of progression (AUC = 0.73) and, after binarization according to a computed cutoff, of timing to dementia.

CONCLUSION

A structured evaluation of apathy, both self-assessed and estimated by caregivers, can provide useful information on the risk and timing of progression from aMCI to dementia. The discrepancy between the two estimates is a fairly reliable index for prediction purposes as a proxy of disease unawareness.

Macrostructural and Microstructural White Matter Alterations Are Associated with Apathy across the Clinical Alzheimer's Disease Spectrum

Apathy is the commonest neuropsychiatric symptom in Alzheimer's disease (AD). Previous findings suggest that apathy is caused by a communication breakdown between functional neural networks involved in motivational-affective processing. This study investigated the relationship between white matter (WM) damage and apathy in AD. Sixty-one patients with apathy (AP-PT) and 61 without apathy (NA-PT) were identified from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database and matched for cognitive status, age and education. Sixty-one cognitively unimpaired (CU) participants were also included as controls. Data on cognitive performance, cerebrospinal fluid biomarkers, brain/WM hyperintensity volumes and diffusion tensor imaging indices were compared across groups. No neurocognitive differences were found between patient groups, but the AP-PT group had more severe neuropsychiatric symptoms. Compared with CU participants, only apathetic patients had deficits on the Clock Drawing Test. AP-PT had increased WM damage, both macrostructurally, i.e., larger WM hyperintensity volume, and microstructurally, i.e., increased radial/axial diffusivity and reduced fractional anisotropy in the fornix, cingulum, anterior thalamic radiations and superior longitudinal and uncinate fasciculi. AP-PT showed signs of extensive WM damage, especially in associative tracts in the frontal lobes, fornix and cingulum. Disruption in structural connectivity might affect crucial functional inter-network communication, resulting in motivational deficits and worse cognitive decline.

Mediation Analyses of the Role of Apathy on Motoric Cognitive Outcomes

Recent literature indicates that apathy is associated with poor cognitive and functional outcomes in older adults, including motoric cognitive risk syndrome (MCR), a predementia syndrome. However, the underlying biological pathway is unknown. The objectives of this study were to (1) examine the cross-sectional associations between inflammatory cytokines (Interleukin 6 (IL-6) and C-Reactive Protein (CRP)) and apathy and (2) explore the direct and indirect relationships of apathy and motoric cognitive outcomes as it relates to important cognitive risk factors. N = 347 older adults (≥65 years old) enrolled in the Central Control of Mobility in Aging Study (CCMA). Linear and logic regression models showed that IL-6, but not CRP was significantly associated with apathy adjusted for age, gender, and years of education (β = 0.037, 95% CI: 0.002-0.072, p = 0.04). Apathy was associated with a slower gait velocity (β = -14.45, 95% CI: -24.89-4.01, p = 0.01). Mediation analyses demonstrated that IL-6 modestly mediates the relationship between apathy and gait velocity, while apathy mediated the relationships between dysphoria and multimorbidity and gait velocity. Overall, our findings indicate that apathy may be an early predictor of motoric cognitive decline. Inflammation plays a modest role, but the underlying biology of apathy warrants further investigation.

Prefrontal Aβ pathology influencing the pathway from apathy to cognitive decline in non-dementia elderly

The purpose of this study is to investigate the complex connection between apathy and cognitive decline that remains unclear. A total of 1057 non-dementia elderly from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database received up to 13 years of follow-up and were divided into an apathy negative (-) group of 943 participants and an apathy positive (+) group of 114 participants through the Neuropsychiatric Inventory (NPI)-apathy subitem. Cerebrospinal fluid (CSF) AD biomarkers and amyloid β (Aβ) PET were measured, and their longitudinal changes were assessed using linear mixed-effects models. Risk factors for cognitive decline and apathy conversion were explored through the Cox proportional hazards model. Mediation effects of Aβ pathology on cognition were investigated using the causal mediation analysis. Apathy syndrome was associated with faster impairment of cognition and elevation of the Aβ burden. The effects of apathy on cognitive function and life quality were mediated by Aβ pathology, including CSF Aβ₄₂/total tau ratio, and Aβ deposition in the prefrontal regions. Apathy syndrome was the risk factor for cognitive deterioration; meanwhile, frontal Aβ burden was the risk factor for apathy conversion. Apathy syndrome is an early manifestation of cognitive decline and there are bidirectional roles between apathy syndrome and Aβ pathology. Prefrontal Aβ pathology influenced the pathway from apathy to cognitive decline.

Associations of Neuropsychiatric Features with Cerebrospinal Fluid Biomarkers of Amyloidogenesis and Neurodegeneration in Dementia with Lewy Bodies Compared with Alzheimer's Disease and Cognitively Healthy People

BACKGROUND

Behavioral features may reflect proteinopathies predicting pathophysiology in neurodegenerative diseases.

OBJECTIVE

We aimed to investigate associations of cerebrospinal fluid biomarkers of amyloidogenesis and neurodegeneration with neuropsychiatric features in dementia with Lewy bodies (DLB) compared with late-onset Alzheimer's disease (AD) and cognitively healthy people.

METHODS

Consecutive outpatients with DLB were paired with outpatients with AD according to sex, dementia stage, and cognitive scores, and with cognitively healthy controls according to sex and age to investigate associations of cerebrospinal fluid amyloid-β (Aβ)42, Aβ40, Aβ38, total tau, phospho-tau Thr181, α-synuclein, ubiquitin, and neurofilament light with neuropsychiatric features according to APOEɛ4 carrier status.

RESULTS

Overall, 27 patients with DLB (78.48±9.0 years old, eleven APOEɛ4 carriers) were paired with 27 patients with AD (81.00±5.8 years old, twelve APOEɛ4 carriers) and 27 controls (78.48±8.7 years old, four APOEɛ4 carriers); two thirds were women. Behavioral burden was more intense in DLB. Biomarker ratios reflecting amyloidogenesis and neurodegeneration in DLB were more similar to those in AD when patients carried APOEɛ4 alleles. After corrections for false discovery rates, the following associations remained significant: in DLB, dysphoria was associated with tauopathy and indirect measures of amyloidogenesis, while in AD, agitation, and night-time behavior disturbances were associated with tauopathy, and delusions were associated with tauopathy and indirect measures of amyloidogenesis.

CONCLUSION

Biomarker ratios were superior to Aβ and tau biomarkers predicting neuropsychiatric symptoms when associations with isolated biomarkers were not significant. At the end, APOEɛ4 carrier status influenced amyloidogenesis and tau pathology in DLB and in AD, and axonal degeneration only in DLB.

Insights into the Pathophysiology of Psychiatric Symptoms in Central Nervous System Disorders: Implications for Early and Differential Diagnosis

Different psychopathological manifestations, such as affective, psychotic, obsessive-compulsive symptoms, and impulse control disturbances, may occur in most central nervous system (CNS) disorders including neurodegenerative and neuroinflammatory diseases. Psychiatric symptoms often represent the clinical onset of such disorders, thus potentially leading to misdiagnosis, delay in treatment, and a worse outcome. In this review, psychiatric symptoms observed along the course of several neurological diseases, namely Alzheimer’s disease, fronto-temporal dementia, Parkinson’s disease, Huntington’s disease, and multiple sclerosis, are discussed, as well as the involved brain circuits and molecular/synaptic alterations. Special attention has been paid to the emerging role of fluid biomarkers in early detection of these neurodegenerative diseases. The frequent occurrence of psychiatric symptoms in neurological diseases, even as the first clinical manifestations, should prompt neurologists and psychiatrists to share a common clinico-biological background and a coordinated diagnostic approach.

Grasping Social Apathy: The Role of Reach-To-Grasp Action Kinematics for the Assessment of Social Apathy in Mild Neurocognitive Disorders

BACKGROUND

Social apathy, a reduction in initiative in proposing or engaging in social activities or interactions, is common in mild neurocognitive disorders (MND). Current apathy assessment relies on self-reports or clinical scales, but growing attention is devoted to defining more objective, measurable and non-invasive apathy proxies.

OBJECTIVE

In the present study we investigated the interest of recording action kinematics in a social reach-to-grasp task for the assessment of social apathy.

METHODS

Thirty participants took part in the study: 11 healthy controls (HC; 6 females, mean age = 68.3±10.5 years) and 19 subjects with MND (13 females, mean age = 75.7±6.3 years). Based on the Diagnostic Criteria for Apathy, MND subjects were classified as socially apathetic (A-MND, N = 9) versus non-apathetic (NA-MND, N = 10). SensRing, a ring-shaped wearable sensor, was placed on their index finger, and subjects were asked to reach and grasp a can to place it into a cup (individual condition) and pass it to a partner (social condition).

RESULTS

In the reach-to-grasp phase of the action, HC and NA-MND showed different acceleration and velocity profiles in the social versus individual condition. No differences were found for A-MND.

CONCLUSION

Previous studies showed the interest of recording patients' level of weekly motor activity for apathy assessment. Here we showed that a 10-min reach-to-grasp task may provide information to differentiate socially apathetic and non-apathetic subjects with MND, thus providing a tool easily usable in the clinical practice. Future studies with a bigger sample are needed to better characterize these findings.

Pharmacologic Approaches for the Management of Apathy in Neurodegenerative Disorders

Apathy is one of the most frequent behavioral disturbances in many neurodegenerative disorders and is known to have a negative impact on the disease progression, particularly in Alzheimer’s disease. Therapeutic options are currently limited and non-pharmacological approaches should constitute first line treatments. Pharmacological agents likely to reduce apathy levels are lacking. The objective of the present article is to review recent pharmacological treatments for apathy in neurodegenerative disorders. The Pubmed database was searched with a particular focus on articles published as of January 2017. Current main levels of evidence have been reported so far with cholinergic, glutamatergic and dopaminergic agents to reduce levels of apathy, despite several conflicting results. Treatment duration and samples sizes may have however decreased the validity of previous results. Ongoing studies involving more participants/treatment duration or distinct neural pathways may provide new insights in the treatment of apathy in neurodegenerative disorders.