Amyloid-β Imaging in Older Adults Presenting to a Memory Clinic with Subjective Cognitive Decline: A Pilot Study

Accelerated long-term forgetting: from subjective memory decline to a defined clinical entity

Subjective memory decline (SMD) might represent the preclinical phase of Alzheimer's disease (AD), and has been reported in epileptic amnesia associated with accelerated long-term forgetting (ALF). We investigated ALF in SMD subjects by means of RAVLT recall and recognition and ROCF recall after 1-week retention and compared with a control group. Two-way ANOVAs for RAVLT and ROCF were conducted, and stepwise regression analysis was administered considering EMQ and DASS-21 as factors. SMD subjects performed significantly worse than controls at 1-week delay on RAVLT recall and recognition, but not on ROCF, and not associated with depression or memory complaints. SMD patients showed ALF, which is usually associated with temporomesial dysfunctions, representing a cognitive marker to assess objectively memory problems in SMD, and to undisclose initial neurodegenerative disease involving temporal structures usually compromised in AD. Therefore, SMD might no longer be "subjective," but rather a specific and defined clinical entity.

Predicting progression of cognitive decline to dementia using dyadic patterns of subjective reporting: evidence from the CompAS longitudinal study

Objective

To analyze the validity of self and informant reports, depressive symptomatology, and some sociodemographic variables to predict the risk of cognitive decline at different follow-up times.

Methods

A total of 337 participants over 50 years of age included in the CompAS and classified as Cognitively Unimpaired (CU), Subjective Cognitive Decline (SCD) and Mild Cognitive Impairment (MCI) groups were assessed at baseline and three follow-ups. A short version of the QAM was administered to assess the severity of subjective cognitive complaints (SCCs), and the GDS-15 was used to evaluate the depressive symptoms. At each follow-up assessment, participants were reclassified according to the stability, regression or progression of their conditions. Logistic regression analysis was used to predict which CU, SCD and MCI participants would remain stable, regress or progress at a 3rd follow-up by using self- and informant-reported complaints, depressive symptomatology, age and education at baseline and 2nd follow-ups as the predictive variables.

Results

Overall, self-reported complaints predicted progression between the asymptomatic and presymptomatic stages. As the objective deterioration increased, i.e., when SCD progressed to MCI or dementia, the SCCs reported by informants proved the best predictors of progression. Depressive symptomatology was also a predictor of progression from CU to SCD and from SCD to MCI.

Conclusion

A late increase in self-reported complaints make valid estimates to predict subjective decline at asymptomatic stages. However, an early increase in complaints reported by informants was more accurate in predicting objective decline from asymptomatic stages. Both, early and late decrease in self-reported complaints successfully predict dementia from prodromic stage. Only late decrease in self-reported complaints predict reversion from prodromic and pre-symptomatic stages.

Low thalamic activity during a digit-symbol substitution task is associated with symptoms of subjective cognitive decline

Introduction

Subjective cognitive decline (SCD) may represent the earliest preclinical stage of Alzheimer's Disease (AD) for some older adults. However, the underlying neurobiology of SCD is not completely understood. Since executive function may be affected earlier than memory function in the progression of AD, we aimed to characterize SCD symptoms in terms of fMRI brain activity during the computerized digit-symbol substitution task (DSST), an executive function task. We also explored associations of DSST task performance with brain activation, SCD severity, and amyloid-ß (Aß) load.

Methods

We analyzed data from 63 cognitively normal older individuals (mean age 73.6 ± 7.2) with varying degree of SCD symptoms. Participants completed a computerized version of DSST in the MR scanner and a Pittsburgh Compound-B (PiB)-PET scan to measure global cerebral Aß load.

Results

A voxel-wise analysis revealed that greater SCD severity was associated with lower dorsomedial thalamus activation. While task performance was not associated with brain activation nor Aß load, slower reaction time was associated with greater SCD severity.

Discussion

The observed lower dorsomedial thalamus activation may reflect declining familiarity-based working memory and the trans-thalamic executive function pathway in SCD. SCD symptoms may reflect altered neural function and subtle decline of executive function, while Aß load may have an indirect impact on neural function and performance. Self-perceived cognitive decline may serve as a psychological/subjective marker reflecting subtle brain changes.

The Importance of Subjective Cognitive Decline Recognition and the Potential of Molecular and Neurophysiological Biomarkers-A Systematic Review

Subjective cognitive decline (SCD) and mild cognitive impairment (MCI) are early stages of Alzheimer's disease (AD). Neurophysiological markers such as electroencephalography (EEG) and event-related potential (ERP) are emerging as alternatives to traditional molecular and imaging markers. This paper aimed to review the literature on EEG and ERP markers in individuals with SCD. We analysed 30 studies that met our criteria, with 17 focusing on resting-state or cognitive task EEG, 11 on ERPs, and two on both EEG and ERP parameters. Typical spectral changes were indicative of EEG rhythm slowing and were associated with faster clinical progression, lower education levels, and abnormal cerebrospinal fluid biomarkers profiles. Some studies found no difference in ERP components between SCD subjects, controls, or MCI, while others reported lower amplitudes in the SCD group compared to controls. Further research is needed to explore the prognostic value of EEG and ERP in relation to molecular markers in individuals with SCD.

Source connectivity patterns in the default mode network differ between elderly golf-novices and non-golfers

Learning to play golf has high demands on attention and therefore may counteract age-related changes of functional brain networks. This cross-sectional study compared source connectivity in the Default Mode Network (DMN) between elderly golf novices and non-golfers. Four-minute resting-state electroencephalography (128 channels) from 22 elderly people (mean age 67 ± 4.3 years, 55% females) were recorded after completing a 22-week golf learning program or after having continued with normal life. Source connectivity was assessed after co-registration of EEG data with native MRI within pre-defined portions of the DMN in the beta band (14-25 Hz). Non-golfers had significantly higher source connectivity values in the anterior DMN compared to non-golfers. Exploratory correlation analyses did not indicate an association to cognitive performance in either group. Inverse correlations between a marker of external attention with source connectivity of the anterior DMN may suggest a trend in the golf group only, but have to be replicated in future studies. Clinical relevance of these findings remains to be elucidated, but the observed difference in the anterior DMN may provide a starting point to further investigate if and how learning golf may have an impact on physiological age-related cognitive changes.

Brain Functional Alterations and Association with Cognition in People with Preclinical Subjective Cognitive Decline and Objective Subtle Cognitive Difficulties

Subjective cognitive decline (SCD) and objective subtle cognitive difficulties (Obj-SCD) are considered the initial stages of aberrant cognition prior to mild cognitive impairment (MCI) due to Alzheimer's disease (AD). We aimed to determine the difference of brain function of SCD and Obj-SCD, furthermore, to figure out which one could be the marker of early AD. One hundred and eighty-five participants were enrolled in this study to determine the amyloid pathology and glucose metabolism changes in SCD and Obj-SCD. The association of amyloid deposition and glucose metabolism with cognitive domains were also investigated. Obj-SCD displayed significantly increased amyloid deposition in frontal and temporal lobes compared to SCD and normal cognitive control (NCC). No difference of amyloid deposition between SCD and NCC, and no difference of glucose metabolism among the three groups were observed. Amyloid deposition was associated with function of memory, language and executive domains, and glucose metabolism was only associated with executive function in Obj-SCD. Amyloid deposition was only associated with executive function in SCD. Obj-SCD could be the early stage of AD, which displayed significant increased amyloid deposition, and the increased amyloid deposition was associated with cognitive function in different domains.

Do informant-reported subjective cognitive complaints predict progression to mild cognitive impairment and dementia better than self-reported complaints in old adults? A meta-analytical study

BACKGROUND

Subjective cognitive complaints (SCCs) are considered a risk factor for objective cognitive decline and conversion to dementia. The aim of this study was to determine whether self-reported or informant-reported SCCs best predict progression to mild cognitive impairment (MCI) and/or dementia.

METHODS

We reviewed prospective longitudinal studies of Cognitively Unimpaired (CU) older adults with self-reported and informant-reported SCCs at baseline, assessed by questions or questionnaires that considered the transition to MCI and/or dementia. A random-effects meta-analysis was performed to obtain pooled estimates and 95% CIs.

RESULTS

Both self-reported and informant-reported SCCs are associated with an elevated risk of transition from CU to MCI and/or dementia. The association appears stronger and more robust for informant-reported data [1.38, with a 95% CI of 1.16 -1.64, p < 0.001] than for self-reported data [1.27 (95% CI 1.06 - 1.534, p = 0.011].

CONCLUSIONS

Our results suggest that corroborated information from one informant could provide important details for distinguishing between normal aging and clinical states.

Plasma amyloid-beta oligomer is related to subjective cognitive decline and brain amyloid status

Background

Subjective cognitive decline (SCD) is a target for Alzheimer’s disease prediction. Plasma amyloid-beta oligomer (AβO), the pathogenic form of Aβ in blood, has recently been proposed as a novel blood-based biomarker of AD prediction by representing brain Aβ deposition. The relationship between plasma AβO, brain Aβ deposition, and SCD in individuals with normal objective cognition has not been investigated.

Methods

In this cross-sectional study, we analyzed 126 participants with normal objective cognition. More SCD symptoms were expressed as higher scores of the Subjective Cognitive Decline Questionnaire (SCDQ) and Memory Age-associated Complaint Questionnaire (MACQ). The plasma AβO level of each participant was measured twice for validation and expressed as a concentration (ng/mL) and a ratio relative to the mean value of two internal standards. Brain Aβ deposition was assessed by [¹⁸F] flutemetamol positron emission tomography (PET) and expressed as standard uptake value ratio (SUVR). Associations of SCDQ and MACQ with plasma AβO levels or SUVR were analyzed in multiple linear regression models. The association between plasma AβO level and flutemetamol PET positivity was assessed in logistic regression and receiver operative characteristic analyses.

Results

Overall, participants were 73.3 years old with female predominance (69.0%). After adjustment for confounders, high SCDQ and MACQ scores were associated with the high plasma AβO levels as both concentrations and ratios (ratios: standardized coefficient = 0.246 and p = 0.023 for SCDQ, standardized coefficient = 0.209 and p = 0.029 for MACQ; concentrations: standardized coefficient = 0.257 and p = 0.015 for SCDQ, standardized coefficient = 0.217 and p = 0.021 for MACQ). In contrast, SCDQ and MACQ were not significantly associated with SUVRs (p = 0.134 for SCDQ, p = 0.079 for MACQ). High plasma AβO levels were associated with flutemetamol PET (+) with an area under the curve of 0.694 (ratio) or 0.662 (concentration). Combined with APOE e4, plasma AβO presented area under the curves of 0.789 (ratio) and 0.783 (concentration).

Conclusions

Our findings indicate that the high plasma AβO level could serve as a potential surrogate biomarker of severe SCD and the presence of brain Aβ deposition in individuals with normal objective cognition.

The role of dyadic cognitive report and subjective cognitive decline in early ADRD clinical research and trials: Current knowledge, gaps, and recommendations

Efficient identification of cognitive decline and Alzheimer's disease (AD) risk in early stages of the AD disease continuum is a critical unmet need. Subjective cognitive decline is increasingly recognized as an early symptomatic stage of AD. Dyadic cognitive report, including subjective cognitive complaints (SCC) from a participant and an informant/study partner who knows the participant well, represents an accurate, reliable, and efficient source of data for assessing risk. However, the separate and combined contributions of self- and study partner report, and the dynamic relationship between the two, remains unclear. The Subjective Cognitive Decline Professional Interest Area within the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment convened a working group focused on dyadic patterns of subjective report. Group members identified aspects of dyadic-report information important to the AD research field, gaps in knowledge, and recommendations. By reviewing existing data on this topic, we found evidence that dyadic measures are associated with objective measures of cognition and provide unique information in preclinical and prodromal AD about disease stage and progression and AD biomarker status. External factors including dyad (participant-study partner pair) relationship and sociocultural factors contribute to these associations. We recommend greater dyad report use in research settings to identify AD risk. Priority areas for future research include (1) elucidation of the contributions of demographic and sociocultural factors, dyad type, and dyad relationship to dyad report; (2) exploration of agreement and discordance between self- and study partner report across the AD syndromic and disease continuum; (3) identification of domains (e.g., memory, executive function, neuropsychiatric) that predict AD risk outcomes and differentiate cognitive impairment due to AD from other impairment; (4) development of best practices for study partner engagement; (5) exploration of study partner report as AD clinical trial endpoints; (6) continued development, validation, and optimization, of study partner report instruments tailored to the goals of the research and population.

Subjective cognitive decline and anxious/depressive symptoms during the COVID-19 pandemic: what is the role of stress perception, stress resilience, and β-amyloid?

Background

The COVID-19 pandemic may worsen the mental health of people reporting subjective cognitive decline (SCD) and therefore their clinical prognosis. We aimed to investigate the association between the intensity of SCD and anxious/depressive symptoms during confinement and the underlying mechanisms.

Methods

Two hundred fifty cognitively unimpaired participants completed the Hospital Anxiety and Depression Scale (HADS) and SCD-Questionnaire (SCD-Q) and underwent amyloid-β positron emission tomography imaging with [18F] flutemetamol (N = 205) on average 2.4 (± 0.8) years before the COVID-19 confinement. During the confinement, participants completed the HADS, Perceived Stress Scale (PSS), Brief Resilience Scale (BRS), and an ad hoc questionnaire on worries (access to primary products, self-protection materials, economic situation) and lifestyle changes (sleep duration, sleep quality, eating habits). We investigated stress-related measurements, worries, and lifestyle changes in relation to SCD. We then conducted an analysis of covariance to investigate the association of SCD-Q with HADS scores during the confinement while controlling for pre-confinement anxiety/depression scores and demographics. Furthermore, we introduced amyloid-β positivity, PSS, and BRS in the models and performed mediation analyses to explore the mechanisms explaining the association between SCD and anxiety/depression.

Results

In the whole sample, the average SCD-Q score was 4.1 (± 4.4); 70 (28%) participants were classified as SCD, and 26 (12.7%) were amyloid-β-positive. During the confinement, participants reporting SCD showed higher PSS (p = 0.035) but not BRS scores (p = 0.65) than those that did not report SCD. No differences in worries or lifestyle changes were observed. Higher SCD-Q scores showed an association with greater anxiety/depression scores irrespective of pre-confinement anxiety/depression levels (p = 0.002). This association was not significant after introducing amyloid-β positivity and stress-related variables in the model (p = 0.069). Amyloid-β positivity and PSS were associated with greater HADS irrespective of pre-confinement anxiety/depression scores (p = 0.023; p < 0.001). The association of SCD-Q with HADS was mediated by PSS (p = 0.01).

Conclusions

Higher intensity of SCD, amyloid-β positivity, and stress perception showed independent associations with anxious/depressive symptoms during the COVID-19 confinement irrespective of pre-confinement anxiety/depression levels. The association of SCD intensity with anxiety/depression was mediated by stress perception, suggesting stress regulation as a potential intervention to reduce affective symptomatology in the SCD population in the face of stressors.

Subjective cognitive decline, mild cognitive impairment, and dementia - syndromic approach: recommendations of the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology

ABSTRACT This consensus, performed by the Brazilian Academy of Neurology (BAN) will approach practically how to evaluate patients with cognitive complaints and how to clinically and etiologically diagnose the three clinical syndromes associated with the different stages of cognitive decline: subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia. This BAN consensus discusses SCD diagnosis for the first time, updates MCI and dementia diagnoses, recommends the adequate cognitive tests and the relevant etiological work-up and care of patients with cognitive decline at different levels of care within the Brazilian Unified Health System. We also review the main assessment instruments used in Brazil and Latin America.

Declínio cognitivo subjetivo, comprometimento cognitivo leve e demência - diagnóstico sindrômico: recomendações do Departamento Científico de Neurologia Cognitiva e do Envelhecimento da Academia Brasileira de Neurologia

RESUMO Este consenso realizado pela Academia Brasileira de Neurologia (ABN) abordará de maneira prática como avaliar pacientes com queixas cognitivas e como realizar o diagnóstico clínico e etiológico das três síndromes clínicas associadas aos estágios de declínio cognitivo: declínio cognitivo subjetivo (DCS), comprometimento cognitivo leve (CCL) e demência. O diagnóstico de DCS é discutido pela primeira vez em consenso da ABN e as atualizações para o diagnóstico de CCL e demência são abordadas, bem como a recomendação para o uso de testes cognitivos apropriados, investigação etiológica pertinente e cuidados aos pacientes com declínio cognitivo nos diferentes níveis de atenção do Sistema Único de Saúde. Foi realizada pesquisa dos principais instrumentos de avaliação utilizados em nosso meio e na América Latina.

Screening of Human Circular RNAs as Biomarkers for Early Onset Detection of Alzheimer’s Disease

Circular RNAs (circRNAs) are a distinctive type of endogenous non-coding RNAs, and their regulatory roles in neurological disorders have received immense attention. CircRNAs significantly contribute to the regulation of gene expression and progression of neurodegenerative disorders including Alzheimer’s disease (AD). The current study aimed to identify circRNAs as prognostic and potential biomarkers in AD. The differentially expressed circRNAs among subjective cognitive decline, amnestic mild cognitive impairment, and age-matched normal donors were determined through Arraystar Human circRNA Array V2 analysis. The annotations of circRNAs-microRNA interactions were predicted by employing Arraystar’s homemade microRNAs (miRNA) target prediction tool. Bioinformatics analyses comprising gene ontology enrichment, KEGG pathway, and network analysis were conducted. Microarray analysis revealed the 33 upregulated and 11 downregulated differentially expressed circRNAs (FC ≥ 1.5 and p-values ≤ 0.05). The top 10 differentially expressed upregulated and downregulated circRNAs have been chosen for further expression validation through quantitative real-time PCR and subsequently, hsa-circRNA_001481 and hsa_circRNA_000479 were confirmed experimentally. Bioinformatics analyses determined the circRNA-miRNA-mRNA interactions and microRNA response elements to inhibit the expression of miRNAs and mRNA targets. Gene ontology enrichment and KEGG pathways analysis revealed the functional clustering of target mRNAs suggesting the functional verification of these two promising circRNAs. It is concluded that human circRNA_001481 and circRNA_000479 could be utilized as potential biomarkers for the early onset detection of AD and the development of effective therapeutics.

Depressive Symptoms Have Distinct Relationships With Neuroimaging Biomarkers Across the Alzheimer’s Clinical Continuum

Background

Depressive and anxiety symptoms are frequent in Alzheimer’s disease and associated with increased risk of developing Alzheimer’s disease in older adults. We sought to examine their relationships to Alzheimer’s disease biomarkers across the preclinical and clinical stages of the disease.

Method

Fifty-six healthy controls, 35 patients with subjective cognitive decline and 56 amyloid-positive cognitively impaired patients on the Alzheimer’s continuum completed depression and anxiety questionnaires, neuropsychological tests and neuroimaging assessments. We performed multiple regressions in each group separately to assess within group associations of depressive and anxiety symptoms with either cognition (global cognition and episodic memory) or neuroimaging data (gray matter volume, glucose metabolism and amyloid load).

Results

Depressive symptoms, but not anxiety, were higher in patients with subjective cognitive decline and cognitively impaired patients on the Alzheimer’s continuum compared to healthy controls. Greater depressive symptoms were associated with higher amyloid load in subjective cognitive decline patients, while they were related to higher cognition and glucose metabolism, and to better awareness of cognitive difficulties, in cognitively impaired patients on the Alzheimer’s continuum. In contrast, anxiety symptoms were not associated with brain integrity in any group.

Conclusion

These data show that more depressive symptoms are associated with greater Alzheimer’s disease biomarkers in subjective cognitive decline patients, while they reflect better cognitive deficit awareness in cognitively impaired patients on the Alzheimer’s continuum. Our findings highlight the relevance of assessing and treating depressive symptoms in the preclinical stages of Alzheimer’s disease.

My Healthy Brain: a multimodal lifestyle program to promote brain health

BACKGROUND

Promoting brain health depends on sustaining healthy behaviors across the lifespan. Yet, public adoption of lifestyle behaviors and knowledge of cognitive decline (CD) prevention remains poor. Our multidisciplinary team developed My Healthy Brain (MHB) to promote a healthy lifestyle (e.g. diet, exercise, alcohol, sleep) and build cognitive reserve (e.g. memory compensatory strategies). Our objective was to demonstrate early proof-of-concept for MHB by exploring the feasibility, acceptability, and improvement in primary lifestyle outcomes as well as secondary outcomes of self-determination and subjective wellbeing.

MATERIALS AND METHODS

Older adults with subjective (self-report only) or objective (confirmed by cognitive testing) CD, referred by neurologists to modify lifestyle risk factors (e.g. sedentary), participated in a non-randomized open pilot of MHB (N = 24). Participants completed the 8-week MHB group (90 min each) and pre-post outcome measures.

RESULTS

MHB met all a-priori set benchmarks, including good feasibility of recruitment (71% of patients screened) and enrollment (75% completed baseline), and good acceptability of treatment (75% completed 6 of 8 sessions and post-testing). Program satisfaction was excellent (100% of participants) and no adverse events were reported. We also observed improvements in primary lifestyle outcomes as well as secondary outcomes of self-determination and subjective well-being.

DISCUSSION

While MHB demonstrated preliminary feasibility and the potential to modify lifestyle risk factors for CD, the program can be improved. Future work will explore the integration of mindfulness skills with behavioral principles to bolster multidomain lifestyle change, and the live video delivery format to bypass barriers to participation.

A Systematic Review of Neuroimaging Studies Comparing Individuals with Subjective Cognitive Decline to Healthy Controls

Background: Individuals with subjective cognitive decline (SCD) are hypothesized to be the earliest along the cognitive continuum between healthy aging and Alzheimer’s disease (AD), although more research is needed on this topic. Given that treatment approaches may be most effective pre-clinically, a primary objective of emerging research is to identify biological markers of SCD using neuroimaging methods. Objective: The current review aimed to comprehensively present the neuroimaging studies on SCD to date. Methods: PubMed and PsycINFO databases were searched for neuroimaging studies of individuals with SCD. Quality assessments were completed using the Appraisal tool for Cross-Sectional Studies. Results: In total, 62 neuroimaging studies investigating differences between participants with SCD and healthy controls were identified. Specifically, the number of studies were as follows: 36 MRI, 6 PET, 8 MRI/PET, 4 EEG, 7 MEG, and 1 SPECT. Across neuroimaging modalities, 48 of the 62 included studies revealed significant differences in brain structure and/or function between groups. Conclusion: Neuroimaging methods can identify differences between healthy controls and individuals with SCD. However, inconsistent results were found within and between neuroimaging modalities. Discrepancies across studies may be best accounted for by methodological differences, notably variable criteria for SCD, and differences in participant characteristics and risk factors for AD. Clinic based recruitment and cross-sectional study design were common and may bias the literature. Future neuroimaging investigations of SCD should consistently incorporate the standardized research criteria for SCD (as recommended by the SCD-Initiative), include more details of their SCD sample and their symptoms, and examine groups longitudinally.

Structural brain network correlations with amyloid burden in elderly individuals at risk of Alzheimer's disease

Alzheimer's disease (AD) has a long preclinical phase during which beta-amyloid accumulates in the brain without cognitive impairment. However, the pattern of brain network alterations in this early stage of the disease remains to be clarified. In this study we examined the relationships between regional brain network indices and beta-amyloid deposits. Twenty-four elderly subjects with the APOE4 allele underwent both a 1.5-Tesla magnetic resonance imaging (MRI) scan and a positron emission tomography (PET) scan using [¹⁸F]Florbetapir. We computed network metrics such as the degree, betweenness centrality, and clustering coefficient, and examined the relationships between the beta-amyloid accumulation and these regional brain network connectivity metrics. We found a significant positive correlation between the global standardized uptake value ratio (SUVR) of [¹⁸F]Florbetapir and the betweenness centrality in the left parietal region. However, there were no significant correlations between the SUVR score and other network indices or the regional gray matter volume. Our data suggest a relationship between the beta-amyloid accumulation and the regional brain network connectivity in subjects at risk of AD. The brain connectome may provide an adjunct biomarker for the early detection of AD.

Self- and Partner-Reported Subjective Memory Complaints: Association with Objective Cognitive Impairment and Risk of Decline

Background

Episodic memory decline is a hallmark of Alzheimer's disease (AD). Subjective memory complaints (SMCs) may represent one of the earliest signs of impending cognitive decline. The degree to which self- or partner-reported SMCs predict cognitive change remains unclear.

Objective

We aimed to evaluate the relationship between self- and partner-reported SMCs, objective cognitive performance, AD biomarkers, and risk of future decline in a well-characterized longitudinal memory center cohort. We also evaluated whether study partner characteristics influence reports of SMCs.

Methods

758 participants and 690 study partners were recruited from the Penn Alzheimer's Disease Research Center Clinical Core. Participants included those with Normal Cognition, Mild Cognitive Impairment, and AD. SMCs were measured using the Prospective and Retrospective Memory Questionnaire (PRMQ), and were evaluated for their association with cognition, genetic, plasma, and neuroimaging biomarkers of AD, cognitive and functional decline, and diagnostic progression over an average of four years.

Results

We found that partner-reported SMCs were more consistent with cognitive test performance and increasing symptom severity than self-reported SMCs. Partner-reported SMCs showed stronger correlations with AD-associated brain atrophy, plasma biomarkers of neurodegeneration, and longitudinal cognitive and functional decline. A 10-point increase on baseline PRMQ increased the annual risk of diagnostic progression by approximately 70%. Study partner demographics and relationship to participants influenced reports of SMCs in AD participants only.

Conclusion

Partner-reported SMCs, using the PRMQ, have a stronger relationship with the neuroanatomic and cognitive changes associated with AD than patient-reported SMCs. Further work is needed to evaluate whether SMCs could be used to screen for future decline.

Translation, cross-cultural adaptation, and validity of the Brazilian version of the Cognitive Function Instrument

Subjective cognitive decline (SCD) is defined as a self-perception of a progressive cognitive impairment, which is not detected objectively through neuropsychological tests. The Alzheimer's Disease Cooperative Study developed the Cognitive Function Instrument (CFI) to evaluate individuals with SCD. The CFI consists of two versions, namely, a self-report and a partner report.

Difference in Amyloid Load Between Single Memory Domain and Multidomain Subjective Cognitive Decline: A Study from the SILCODE

Background: Subjective cognitive decline (SCD), an at-risk condition of Alzheimer’s disease (AD), can involve various cognitive domains, such as memory, language, planning, and attention. Objective: We aims to explore the differences in amyloid load between the single memory domain SCD (sd-SCD) and the multidomain SCD (md-SCD) and assess the relationship of amyloid pathology with quantitative SCD scores and objective cognition. Methods: A total of 63 SCD participants from the SILCODE study underwent the clinical evaluation, neuropsychological assessment, and 18F-florbetapir PET scan. Global amyloid standard uptake value ratio (SUVr) was calculated. Additionally, regional amyloid SUVr was quantified in 12 brain regions of interests. A nonparametric rank ANCOVA was used to compare the global and regional amyloid SUVr between the md-SCD (n = 34) and sd-SCD (n = 29) groups. A multiple linear regression analysis was conducted to test the relationship of amyloid SUVr with quantitative SCD scores and objective cognition. Results: Compared with individuals with sd-SCD, individuals with md-SCD had increased global amyloid SUVr (F = 5.033, p = 0.029) and regional amyloid SUVr in the left middle temporal gyrus (F = 12.309, p = 0.001; Bonferroni corrected), after controlling for the effects of age, sex, and education. When pooling all SCD participants together, the increased global amyloid SUVr was related with higher SCD-plus sum scores and lower Auditory Verbal Learning Test-delayed recall scores. Conclusion: According to our findings, individuals with md-SCD showed higher amyloid accumulation than individuals with sd-SCD, suggesting that md-SCD may experience a more advanced stage of SCD. Additionally, increased global amyloid load was predictive of a poorer episodic memory function in SCD individuals.

Subjective cognitive decline: opposite links to neurodegeneration across the Alzheimer's continuum

Subjective memory decline is associated with neurodegeneration and increased risk of cognitive decline in participants with no or subjective cognitive impairment, while in patients with mild cognitive impairment or Alzheimer's-type dementia, findings are inconsistent. Our aim was to provide a comprehensive overview of subjective memory decline changes, relative to objective memory performances, and of their relationships with neurodegeneration, across the clinical continuum of Alzheimer's disease. Two hundred participants from the Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce (IMAP+) primary cohort and 731 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) replication cohort were included. They were divided into four clinical groups (Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce/Alzheimer's Disease Neuroimaging Initiative): controls (n = 67/147, age: 60-84/60-90, female: 54/55%), patients with subjective cognitive decline (n = 30/84, age: 54-84/65-80, female: 44/63%), mild cognitive impairment (n = 50/369, age: 58-86/55-88, female: 45/44%) or Alzheimer's-type dementia (n = 36/121, age: 51-86/61-90, female: 41/41%). Subjective and objective memory scores, and their difference (i.e. delta score reflecting memory awareness), were compared between groups. Then, voxelwise relationships between subjective memory decline and neuroimaging measures of neurodegeneration [atrophy (T1-MRI) and hypometabolism (¹⁸F-fluorodeoxyglucose-PET)] were assessed across clinical groups and the interactive effect of the level of cognitive impairment within the entire sample was assessed. Analyses were adjusted for age, sex and education, and repeated including only the amyloid-positive participants. In Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce, the level of subjective memory decline was higher in all patient groups (all P < 0.001) relative to controls, but similar between patient groups. In contrast, objective memory deficits progressively worsened from the subjective cognitive decline to the dementia group (all P < 0.001). Accordingly, the delta score showed a progressive decline in memory awareness across clinical groups (all P < 0.001). Voxelwise analyses revealed opposite relationships between the subjective memory decline score and neurodegeneration across the clinical continuum. In the earliest stages (i.e. patients with subjective cognitive decline or Mini Mental State Examination > 28), greater subjective memory decline was associated with increased neurodegeneration, while in later stages (i.e. patients with mild cognitive impairment, dementia or Mini Mental State Examination < 27) a lower score was related to more neurodegeneration. Similar findings were recovered in the Alzheimer's Disease Neuroimaging Initiative replication cohort, with slight differences according to the clinical group, and in the amyloid-positive subsamples. Altogether, our findings suggest that the subjective memory decline score should be interpreted differently from normal cognition to dementia. Higher scores might reflect greater neurodegeneration in earliest stages, while in more advanced stages lower scores might reflect decreased memory awareness, i.e. more anosognosia associated with advanced neurodegeneration.

Association between specific types of physical activity during the COVID-19 pandemic and the risk of subjective memory decline: findings from the PAMPA Cohort

OBJECTIVES

This study aimed to identify the effects of different physical activities practised during the time period when COVID-19 social distancing measures were in place on the risk of subjective memory decline in adults.

STUDY DESIGN

Retrospective cohort study.

METHODS

Data from the Prospective Study about Mental and Physical Health (PAMPA), a state-level (Rio Grande do Sul, Brazil), online-based cohort study, were analysed. Respondents were asked to rate their memory before COVID-19 social distancing measures were implemented (retrospectively) and on the day that the survey was completed. Subjective memory decline was defined as a perceived worsening of memory function during COVID-19 social distancing compared with the pre-pandemic period. The types of physical activity practised before and during COVID-19 social distancing measures were assessed.

RESULTS

Data from 2319 adults were included. Out-of-home endurance, muscle strengthening, combined endurance and muscle strengthening, and stretching activities reduced the risk of subjective memory decline during the pandemic. In terms of physical activities practised at home, only muscle strengthening did not protect against subjective memory decline. Participants who sustained any type of physical activity at home during the COVID-19 pandemic showed a reduced risk for subjective memory decline.

CONCLUSIONS

Physical activity, regardless of the type of activity and location performed, during the time period when COVID-19 social distancing measures were in place can mitigate the effects of the pandemic on subjective memory decline.

Associations Between Cognitive Complaints, Memory Performance, Mood, and Amyloid-β Accumulation in Healthy Amyloid Negative Late-Midlife Individuals

BACKGROUND

Cognitive complaints are gaining more attention as they may represent an early marker of increased risk for AD in individuals without objective decline at standard neuropsychological examination.

OBJECTIVE

Our aim was to assess whether cognitive complaints in late middle-aged individuals not seeking medical help are related to objective cognitive outcomes known as early markers for AD risk, concomitant affective state, and amyloid-β (Aβ) burden.

METHODS

Eighty-seven community-based cognitively normal individuals aged 50-69 years underwent neuropsychological assessment for global cognition, using Preclinical Alzheimer's Cognitive Composite 5 (PACC5) score, and a more specific episodic memory measure. Affective state was based on self-assessment questionnaires for depression and anxiety. Aβ PET burden was assessed via [18F]Flutemetamol (N = 84) and [18F]Florbetapir (N = 3) uptake. Cognitive complaints were evaluated using Cognitive Difficulties Scale.

RESULTS

Higher cognitive complaints were significantly associated with lower episodic memory performance and worse affective state. Moreover, higher level of cognitive complaints was related to higher (but still sub-clinical) global Aβ accumulation (at uncorrected significance level). Importantly, all three aspects remained significant when taken together in the same statistical model, indicating that they explained distinct parts of variance.

CONCLUSION

In healthy Aβ negative late middle-aged individuals, a higher degree of cognitive complaints is associated with lower episodic memory efficiency, more anxiety and depression, as well as, potentially, with higher Aβ burden, suggesting that complaints might signal subtle decline. Future studies should untangle how cognitive complaints in healthy aging populations are related to longitudinal changes in objective cognition and AD biomarker correlates.

The interplay between gray matter and white matter neurodegeneration in subjective cognitive decline

Aims: To investigate the interplay between gray matter (GM) and white matter (WM) neurodegeneration in subjective cognitive decline (SCD), including thickness across the whole cortical mantle, hippocampal volume, and integrity across the whole WM.

Methods: We included 225 cognitively unimpaired individuals from a community-based cohort. Subjective cognitive complaints were assessed through 9 questions covering amnestic and non-amnestic cognitive domains. In our cohort, 123 individuals endorsed from one to six subjective cognitive complaints (i.e. they fulfilled the diagnostic criteria for SCD), while 102 individuals reported zero complaints. GM neurodegeneration was assessed through measures of cortical thickness across the whole mantle and hippocampal volume. WM neurodegeneration was assessed through measures of mean diffusivity (MD) across the whole WM skeleton. Mediation analysis and multiple linear regression were conducted to investigate the interplay between the measures of GM and WM neurodegeneration.

Results: A higher number of complaints was associated with reduced hippocampal volume, cortical thinning in several frontal and temporal areas and the insula, and higher MD across the WM skeleton, with a tendency to spare the occipital lobe. SCD-related cortical thinning and increased MD were associated with each other and jointly contributed to complaints, but the contribution of cortical thinning to the number of complaints was stronger.

Conclusions: Neurodegeneration processes affecting the GM and WM seem to be associated with each other in SCD and include brain areas other than those typically targeted by Alzheimer’s disease. Our findings suggest that SCD may be a sensitive behavioral marker of heterogeneous brain pathologies in individuals recruited from the community.

The Anterior-posterior Functional Connectivity Disconnection in the Elderly with Subjective Memory Impairment and Amnestic Mild Cognitive Impairment

BACKGROUND

Subjective Memory Impairment (SMI) may tremendously increase the risk of Alzheimer's Disease (AD). The full understanding of the neuromechanism of SMI will shed light on the early intervention of AD.

METHODS

In the current study, 23 Healthy Controls (HC), 22 SMI subjects and 24 amnestic Mild Cognitive Impairment (aMCI) subjects underwent the comprehensive neuropsychological assessment and the resting-state functional magnetic resonance imaging scan. The difference in the connectivity of the Default Mode Network (DMN) and Functional Connectivity (FC) from the Region of Interest (ROI) to the whole brain were compared, respectively.

RESULTS

The results showed that HC and SMI subjects had significantly higher connectivity in the region of the precuneus area compared to aMCI subjects. However, from this region to the whole brain, SMI and aMCI subjects had significant FC decrease in the right anterior cingulum, left superior frontal and left medial superior frontal gyrus compared to HC. In addition, this FC change was significantly correlated with the cognitive function decline in participants.

CONCLUSION

Our study indicated that SMI subjects had relatively intact DMN connectivity but impaired FC between the anterior and posterior brain. The findings suggest that long-distance FC is more vulnerable than the short ones in the people with SMI.

The roles of study setting, response bias, and personality in subjective memory complaints of cognitively normal older adults

OBJECTIVES

This study investigated subjective memory complaints in older adults and the roles of setting, response bias, and personality.

DESIGN

Cognitively normal older adults from two settings completed questionnaires measuring memory complaints, response bias, and personality.

SETTINGS

(A) Neuroimaging study with community-based recruitment and (B) academic memory clinic.

PARTICIPANTS

Cognitively normal older adults who (A) volunteer for research (N = 92) or (B) self-referred to a memory clinic (N = 20).

MEASUREMENTS

Neuropsychological evaluation and adjudication of normal cognitive status were done by the neuroimaging study or memory clinic. This study administered self-reports of subjective memory complaints, response bias, five-factor personality, and depressive symptoms. Primary group differences were examined with secondary sensitivity analyses to control for sex, age, and education differences.

RESULTS

There was no significant difference in over-reporting response bias between study settings. Under-reporting response bias was higher in volunteers. Cognitive complaints were associated with response bias for two cognitive complaint measures. Neuroticism was positively associated with over-reporting in evaluation-seekers and negatively associated with under-reporting in volunteers. The relationship was reversed for Extraversion. Under-reporting bias was positively correlated with Agreeableness and Conscientiousness in volunteers.

CONCLUSION

Evaluation-seekers do not show bias toward over-reporting symptoms compared to volunteers. Under-reporting response bias may be important to consider when screening for memory impairment in non-help-seeking settings. The Memory Functioning Questionnaire was less sensitive to reporting biases. Over-reporting may be a facet of higher Neuroticism. Findings help elucidate psychological influences on self-perceived cognitive decline and help seeking in aging and may inform different strategies for assessment by setting.

Subjective Cognitive Decline May Be Associated With Post-operative Delirium in Patients Undergoing Total Hip Replacement: The PNDABLE Study

Objective: Subjective cognitive decline (SCD) is associated with an increased risk of clinical cognitive disorders. Post-operative delirium (POD) is a common complication after total hip replacement. We aimed to investigate the relationship between SCD and POD in patients undergoing total hip replacement. Methods: Our study recruited 214 cognitively intact individuals from the Perioperative Neurocognitive Disorder And Biomarker Lifestyle (PNDABLE) study in the final analysis. SCD was diagnosed with Subjective Cognitive Decline Scale (SCDS), Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA). The incidence of POD was evaluated by using Confusion Assessment Method (CAM), and POD severity was measured by using the Memorial Delirium Assessment Scale (MDAS). Preoperative cerebrospinal fluid (CSF) Aβ40, Aβ42, T-tau, and P-tau levels were measured by enzyme-linked immune-sorbent assay (ELISA). Results: Overall, the incidence of POD was 26.64% (57/214), including 32.43% (36/111) in the SCD group and 20.39% (21/103) in the NC group. With the increase of age, the incidence of POD in all age groups increased (P < 0.05). Logistic regression analysis showed that after adjusting for SCD, Aβ42, Aβ40, P-tau, and T-tau, SCD (OR 2.32, CI 1.18-4.55, P = 0.01) and the increased CSF level of P-tau (OR 1.04, CI 1.01-1.06, P < 0.001) were risk factors for POD, while the level of aβ42 (OR 0.99, CI 0.99-1.00, P < 0.001) was a protective factor for POD. Conclusion: SCD is one of the preoperative risk factors for POD. Clinical Trial Registration: This study was registered at China Clinical Trial Registry (Chictr200033439).

An Effect of Education on Memory-Encoding Activation in Subjective Cognitive Decline

BACKGROUND

Subjective cognitive decline (SCD) may be an early manifestation of pre-clinical Alzheimer's disease. Elevated amyloid-β (Aβ) is a correlate of SCD symptoms in some individuals. The underlying neural correlates of SCD symptoms and their association with Aβ is unknown. SCD is a heterogeneous condition, and cognitive reserve may explain individual differences in its neural correlates.

OBJECTIVE

We investigated the association between brain activation during memory encoding and SCD symptoms, as well as with Aβ, among older individuals. We also tested the moderating role of education (an index of cognitive reserve) on the associations.

METHODS

We measured brain activation during the "face-name" memory-encoding fMRI task and Aβ deposition with Pittsburgh Compound-B (PiB)-PET among cognitively normal older individuals (n = 63, mean age 73.1 ± 7.4 years). We tested associations between activation and SCD symptoms by self-report measures, Aβ, and interactions with education.

RESULTS

Activation was not directly associated with SCD symptoms or Aβ. However, education moderated the association between activation and SCD symptoms in the executive control network, salience network, and subcortical regions. Greater SCD symptoms were associated with greater activation in those with higher education, but with lower activation in those with lower education.

CONCLUSION

SCD symptoms were associated with different patterns of brain activation in the extended memory system depending on level of cognitive reserve. Greater SCD symptoms may represent a saturation of neural compensation in individuals with greater cognitive reserve, while it may reflect diminishing neural resources in individuals with lower cognitive reserve.

Learning to play golf for elderly people with subjective memory complaints: feasibility of a single-blinded randomized pilot trial

BACKGROUND

Subjective Memory Complaints (SMC) in elderly people due to preclinical Alzheimer's Disease may be associated with dysregulation of the Kynurenine Pathway (KP), with an increase in neurotoxic metabolites that affect cognition. Golf is a challenging sport with high demands on motor, sensory, and cognitive abilities, which might bear the potential to attenuate the pathological changes of preclinical AD. This trial investigated the feasibility of learning to play golf for elderly with cognitive problems and its effects on cognitive functions and the KP.

METHODS

In a 22-week single-blinded randomized controlled trial, elderly people with SMC were allocated to the golf (n = 25, 180 min training/week) or control group (n = 21). Primary outcomes were feasibility (golf exam, adherence, adverse events) and general cognitive function (Alzheimer's Disease Assessment Scale). Secondary outcomes include specific cognitive functions (Response Inhibition, Corsi Block Tapping Test, Trail Making Test), KP metabolites and physical performance (6-Minute-Walk-Test). Baseline-adjusted Analysis-of-Covariance was conducted for each outcome.

RESULTS

42 participants were analyzed. All participants that underwent the golf exam after the intervention passed it (20/23). Attendance rate of the golf intervention was 75 %. No adverse events or drop-outs related to the intervention occurred. A significant time*group interaction (p = 0.012, F = 7.050, Cohen's d = 0.89) was found for correct responses on the Response Inhibition task, but not for ADAS-Cog. Moreover, a significant time*group interaction for Quinolinic acid to Tryptophan ratios (p = 0.022, F = 5.769, Cohen's d = 0.84) in favor of the golf group was observed. An uncorrected negative correlation between attendance rate and delta Quinolinic acid to Kynurenic acid ratios in the golf group (p = 0.039, r=-0.443) was found as well.

CONCLUSIONS

The findings indicate that learning golf is feasible and safe for elderly people with cognitive problems. Preliminary results suggest positive effects on attention and the KP. To explore the whole potential of golfing and its effect on cognitive decline, a larger cohort should be studied over a longer period with higher cardiovascular demands.

TRIAL REGISTRATION

The trial was retrospectively registered (2nd July 2018) at the German Clinical Trials Register ( DRKS00014921 ).

Cardiac-induced cerebral pulsatility, brain structure, and cognition in middle and older-aged adults

Changes of cardiac-induced regional pulsatility can be associated with specific regions of brain volumetric changes, and these are related with cognitive alterations. Thus, mapping of cardiac pulsatility over the entire brain can be helpful to assess these relationships. A total of 108 subjects (age: 66.5 ± 8.4 years, 68 females, 52 healthy controls, 11 subjective cognitive decline, 17 impaired without complaints, 19 MCI and 9 AD) participated. The pulsatility map was obtained directly from resting-state functional MRI time-series data at 3T. Regional brain volumes were segmented from anatomical MRI. Multidomain neuropsychological battery was performed to test memory, language, attention and visuospatial construction. The Montreal Cognitive Assessment (MoCA) was also administered. The sparse partial least square (SPLS) method, which is desirable for better interpreting high-dimensional variables, was applied for the relationship between the entire brain voxels of pulsatility and 45 segmented brain volumes. A multiple holdout SPLS framework was used to optimize sparsity for assessing the pulsatility-volume relationship model and to test the reliability by fitting the models to 9 different splits of the data. We found statistically significant associations between subsets of pulsatility voxels and subsets of segmented brain volumes by rejecting the omnibus null hypothesis (any of 9 splits has p < 0.0056 (=0.05/9) with the Bonferroni correction). The pulsatility was positively associated with the lateral ventricle, choroid plexus, inferior lateral ventricle, and 3rd ventricle and negatively associated with hippocampus, ventral DC, and thalamus volumes for the first pulsatility-volume relationship. The pulsatility had an additional negative relationship with the amygdala and brain stem volumes for the second pulsatility-volume relationship. The spatial distribution of correlated pulsatility was observed in major feeding arteries to the brain regions, ventricles, and sagittal sinus. The indirect mediating pathways through the volumetric changes were statistically significant between the pulsatility and multiple cognitive measures (p < 0.01). Thus, the cerebral pulsatility, along with volumetric measurements, could be a potential marker for better understanding of pathophysiology and monitoring disease progression in age-related neurodegenerative disorders.

Amyloid-β positive individuals with subjective cognitive decline present increased CSF neurofilament light levels that relate to lower hippocampal volume

Neurofilament light chain (NfL) is an axonal protein that when measured in cerebrospinal fluid (CSF) serves as a biomarker of neurodegeneration. We aimed at investigating the association among CSF NfL, presence of Subjective Cognitive Decline (SCD) and hippocampal volume, and how CSF amyloid-β (Aβ) modifies these associations. We included 278 cognitively unimpaired participants from the Alfa+ cohort (78 SCD and 200 Controls). Linear models accounting for covariates (age, gender, and mood) were used to test the association between CSF NfL and SCD status, and between CSF NfL and bilateral hippocampal volumes. Interactions with Aβ were also explored. Individuals with SCD had higher CSF NfL and lower CSF Aβ42/40 than Controls. There was a significant interaction between SCD and CSF-Aβ42/40 levels. Stratified analyses showed a significant association between SCD and NfL only in Aβ+ individuals. Higher CSF NfL was significantly associated with lower hippocampal volume specifically in Aβ+ individuals with SCD. The presence of SCD in Aβ+ individuals may represent an early symptom in the Alzheimer's continuum related to incipient neurodegeneration.

Heterogeneity of Amyloid Binding in Cognitively Impaired Patients Consecutively Recruited from a Memory Clinic: Evaluating the Utility of Quantitative 18F-Flutemetamol PET-CT in Discrimination of Mild Cognitive Impairment from Alzheimer's Disease and Other Dementias

BACKGROUND

With the more widespread use of 18F-radioligand-based amyloid-β (Aβ) PET-CT imaging, we evaluated Aβ binding and the utility of neocortical 18F-Flutemetamol standardized uptake value ratio (SUVR) as a biomarker.

OBJECTIVE

18F-Flutemetamol SUVR was used to differentiate 1) mild cognitive impairment (MCI) from Alzheimer's disease (AD), and 2) MCI from other non-AD dementias (OD).

METHODS

109 patients consecutively recruited from a University memory clinic underwent clinical evaluation, neuropsychological test, MRI and 18F-Flutemetamol PET-CT. The diagnosis was made by consensus of a panel consisting of 1 neuroradiologist and 2 geriatricians. The final cohort included 13 subjective cognitive decline (SCD), 22 AD, 39 MCI, and 35 OD. Quantitative analysis of 16 region-of-interests made by Cortex ID software (GE Healthcare).

RESULTS

The global mean 18F-Flutemetamol SUVR in SCD, MCI, AD, and OD were 0.50 (SD-0.08), 0.53 (SD-0.16), 0.76 (SD-0.10), and 0.56 (SD-0.16), respectively, with SUVR in SCD and MCI and OD being significantly lower than AD. Aβ binding in SCD, MCI, and OD was heterogeneous, being 23%, 38.5%, and 42.9% respectively, as compared to 100% amyloid positivity in AD. Using global SUVR, ROC analysis showed AUC of 0.868 and 0.588 in differentiating MCI from AD and MCI from OD respectively.

CONCLUSION

18F-Flutemetamol SUVR differentiated MCI from AD with high efficacy (high negative predictive value), but much lower efficacy from OD. The major benefit of the test was to differentiate cognitively impaired patients (either SCD, MCI, or OD) without AD-related-amyloid-pathology from AD in the clinical setting, which was under-emphasized in the current guidelines proposed by Amyloid Imaging Task Force.

The impact of aging in dementia: It is time to refocus attention on the main risk factor of dementia

Alzheimer's disease (AD) represents the most common form of dementia among old age subjects, and despite decades of studies, the underlying etiopathogenetic mechanisms remain unsolved, and no cure is available. The amyloid hypothesis has been recently questioned due to the failure of amyloid-centered treatments. The fact that cognitively normal old age subjects have substantial amyloid deposition in the brain comparable to the levels observed in AD patients suggests that amyloid accumulation may enter into the normal process of aging and what really triggers neuronal death and clinical manifestation is the loss of function due to an energetic failure. With this viewpoint article, we aim to challenge the traditional view of amyloid as the leading cause of AD. Conversely, we propose the core feature of aging, that is the progressive brain energy decline, as the main risk factor for dementia in older persons. Thus, a bioenergetic deficit secondary to mitochondrial dysfunction may lead to progressive neuronal death and clinical expression of dementia. The optimization of brain energetics should become a key component in future strategies for preventing and treating dementia.

Education Exerts Different Effects on Cognition in Individuals with Subjective Cognitive Decline and Cognitive Impairment: A Population-Based Study

BACKGROUND

Education plays a potential important effect on the prevalence and incidence of dementia. However, most of the evidence based on convenience sampling.

OBJECTIVE

To explore effects of education on cognition in individuals with subjective cognitive decline (SCD) and cognitive impairment (CI) from a population-based study.

METHODS

We examined the effect of education on cognition among individuals with SCD (n = 451) and CI (n = 280) from a population-based study. A series of neuropsychological tests of memory, executive, language, and general cognitive function were used to assess the participants.

RESULTS

Multiple regression analyses revealed that education has a positive effect on cognition in both SCD and CI group in the population-based research. Further stratification study showed that the beneficial effect of education remains in the SCD group regardless of the education level, especially in the SCD participants with a low education level. However, that effect of education exists in the CI group with a low education level and disappears in the high education level.

CONCLUSION

These results from a population-based sample suggest that high educational attainment may delay cognitive decline in the individuals with SCD regardless of high or low educational level, and high education only predicts cognition in those in the low educational level in CI group.

An approach to classifying subjective cognitive decline in community-dwelling elders

INTRODUCTION

Subjective cognitive decline (SCD) may be an early symptomatic manifestation of Alzheimer's disease, though published research largely neglects how to classify SCD in community-based studies.

METHODS

In neuropsychologically intact Einstein Aging Study participants (n = 1115; mean age = 78; 63% female; 30% non-White), we used Cox models to examine the association between self-perceived cognitive functioning at baseline (using three different approaches) and incident amnestic mild cognitive impairment (aMCI) with covariates of age, sex, education, race/ethnicity, general (objective) cognition, depressive symptoms, and four other SCD-related features.

RESULTS

After a median of 3 years, 198 participants developed aMCI. In models that included all the variables, self-perceived cognitive functioning was consistently associated with incident aMCI as were age, general cognition, and perceived control; apolipoprotein E (APOE) ε4 allele status was significant in one model. We set cut points that optimized the diagnostic accuracy of SCD at various time frames.

DISCUSSION

We provide an approach to SCD classification and discuss implications for cognitive aging studies.

Neuroimaging advances regarding subjective cognitive decline in preclinical Alzheimer's disease

Subjective cognitive decline (SCD) is regarded as the first clinical manifestation in the Alzheimer’s disease (AD) continuum. Investigating populations with SCD is important for understanding the early pathological mechanisms of AD and identifying SCD-related biomarkers, which are critical for the early detection of AD. With the advent of advanced neuroimaging techniques, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), accumulating evidence has revealed structural and functional brain alterations related to the symptoms of SCD. In this review, we summarize the main imaging features and key findings regarding SCD related to AD, from local and regional data to connectivity-based imaging measures, with the aim of delineating a multimodal imaging signature of SCD due to AD. Additionally, the interaction of SCD with other risk factors for dementia due to AD, such as age and the Apolipoprotein E (ApoE) ɛ4 status, has also been described. Finally, the possible explanations for the inconsistent and heterogeneous neuroimaging findings observed in individuals with SCD are discussed, along with future directions. Overall, the literature reveals a preferential vulnerability of AD signature regions in SCD in the context of AD, supporting the notion that individuals with SCD share a similar pattern of brain alterations with patients with mild cognitive impairment (MCI) and dementia due to AD. We conclude that these neuroimaging techniques, particularly multimodal neuroimaging techniques, have great potential for identifying the underlying pathological alterations associated with SCD. More longitudinal studies with larger sample sizes combined with more advanced imaging modeling approaches such as artificial intelligence are still warranted to establish their clinical utility.

Depression and APOEε4 Status in Individuals with Subjective Cognitive Decline: A Meta-Analysis

OBJECTIVE

To evaluate the associative role of depression and apolipoprotein E epsilon 4 allele (APOEε4) in subjective cognitive decline (SCD) and its progression to objective cognitive decline.

METHODS

After literature search in electronic databases, studies were selected by following precise eligibility criteria. Meta-analyses were performed to examine the role of APOEε4 and depression in SCD or its progression to mild cognitive impairment (MCI) or dementia.

RESULTS

APOEε4 positivity was not different between SCD and normal individuals but was significantly higher in individuals with SCD plus than in normal individuals [odds ratio: 2.39 (95% CI: 1.87, 3.05); p<0.00001] and in SCD converters than in non-converters [odds ratio: 5.19 (95% CI: 2.36, 11.42); p<0.00001]. Depression was significantly higher in individuals with SCD [standardized mean difference: 0.63 (0.45, 0.82); p<0.00001] and SCD plus [standardized mean difference: 0.83 (0.43, 1.22); p<0.0001] than in normal individuals. However, depression was not different between SCD and MCI or between SCD converters and non-converters. Age of SCD converters was higher than non-converters [mean difference: 2.95 years (0.58, 5.31)].

CONCLUSION

Whereas APOEε4 positivity was higher in SCD plus and SCD converters, depression was higher in SCD and SCD plus but was not different between SCD and MCI.

Hippocampal sclerosis, TDP-43, and the duration of the symptoms of dementia of AD patients

OBJECTIVES

To examine the relationship between duration of the cognitive symptoms, from the earliest reported symptom to death, and hippocampal sclerosis (HS) and TAR-DNA binding protein of 43kDA (TDP-43) in Alzheimer's disease (AD) patients.

METHODS

The study was conducted in 359 cognitively impaired patients who met the pathological criteria for AD (NIA-Reagan intermediate or high). The mean age at onset was 69.5 ± 8.8 years (range 37-95) and the mean duration of the symptoms was 10.5 ± 4.2 years. The association between symptoms duration and HS and TDP-43 was examined with logistic regression analyses controlling for age at death, atherosclerosis in the Circle of Willis (CW), cerebral infarcts, gender, baseline Mini Mental State Examination scores, APOE-4 allele, and presence of Lewy bodies (LB).

RESULTS

HS was present in 18% (n = 64) and TDP-43 in 51.5% (n = 185) of the patients. HS and TDP-43 were more frequent in patients whose symptoms lasted more than 10 years. LBs were present in 72% of the patients with HS and in 64% of the patients with TDP-43. Age at onset was not associated with TDP-43 or HS. HS was associated with duration of symptoms and LB, TDP-43, and atherosclerosis in the CW. TDP-43 was associated with duration of symptoms, LB, and HS.

INTERPRETATION

HS and TDP-43 are present in early and late onset AD. However, their presence is mainly driven by the duration of symptoms and the presence of LB. This suggests that HS and TDP-43 are part of the later neuropathological changes in AD.

In multiple facets of subjective memory decline sex moderates memory predictions

INTRODUCTION

Two established subjective memory decline facets (SMD; complaints, concerns) are early indicators of memory decline and Alzheimer's disease. We report (1) a four-facet SMD inventory (memory complaints, concerns, compensation, self-efficacy) and (2) prediction of memory change and moderation by sex.

METHODS

The longitudinal design featured 40 years (53 to 97) of non-demented aging (n = 580) from the Victoria Longitudinal Study. Statistical analyses included confirmatory factor analyses and conditional latent growth modeling.

RESULTS

The four-facet SMD Inventory was psychometrically confirmed. Longitudinal analyses revealed significant variability in level and change for SMD and memory. Prediction analyses showed complaints and concerns predicted lower level and steeper memory decline; however, follow-up moderation analyses revealed selective predictions for females. Memory compensation predicted decline overall. Lower memory self-efficacy predicted steeper decline selectively for males.

DISCUSSION

Although traditional and novel SMD facets predicted memory decline, differential sex moderation was observed. SMD research benefits from conceptual complementarity and precision prediction.

Relationship between subjective memory complaints and social and leisure activities in community-dwelling older people: Toyoake Integrated Care Study

AIM

Subjective memory complaints (SMC) have attracted attention in recent years in relation to the early stages of dementia. However, it is not clear whether SMC are related to social and leisure activities. The aim of this study was to evaluate SMC in relation to activities in community-dwelling older adults.

METHODS

A questionnaire inquiring about SMC and social and leisure activities was sent to 14 850 people aged ≥65 years residing in Toyoake City, as part of the Toyoake Integrated Care Study. After a preliminary analysis, we targeted respondents aged ≥70 years. Therefore, 6685 people were included in the analysis. Three question items were used detecting SMC: the feeling of a memory problem (SMC-1), memory loss pointed out by others (SMC-2) and difficulty in recalling today's date (SMC-3). Logistic regression was carried out to determine the relationship between SMC and activities.

RESULTS

In response to SMC-1, 2 and 3, 45.3%, 13.3% and 23.5% participants, respectively, agreed with the statement. Social and leisure activities were negatively associated with SMC-2 and SMC-3, after controlling for confounding factors (SMC-2: odds ratio 0.76, 95% confidence interval 0.65-0.89; SMC-3: odds ratio 0.79, 95% confidence interval 0.70-0.90). However, a significant increase in participation in social and leisure activities was associated with a positive response to SMC-1 (SMC-1: odds ratio 1.24, 95% confidence interval 1.12-1.38). Conclusion A relationship was observed between SMC and social and leisure activities in community-dwelling older people, although differences in the impact of SMC were seen depending on the question asked. Geriatr Gerontol Int 2020; 20: 867-872.

Minor neuropsychological deficits in patients with subjective cognitive decline

OBJECTIVE

To determine the nature and extent of minor neuropsychological deficits in patients with subjective cognitive decline (SCD) and their association with CSF biomarkers of Alzheimer disease (AD).

METHOD

We analyzed data from n = 449 cognitively normal participants (n = 209 healthy controls, n = 240 patients with SCD) from an interim data release of the German Center for Neurodegenerative Diseases Longitudinal Cognitive Impairment and Dementia Study (DELCODE). An extensive neuropsychological test battery was applied at baseline for which we established a latent, 5 cognitive domain factor structure comprising learning and memory, executive functions, language abilities, working memory, and visuospatial functions. We compared groups in terms of global and domain-specific performance and correlated performance with different CSF markers of AD pathology.

RESULTS

We observed worse performance (Cohen d = ≈0.25-0.5, adjusted for age, sex differences with analysis of covariance) in global performance, memory, executive functions, and language abilities for the SCD group compared to healthy controls. In addition, worse performance in these domains was moderately (r = ≈0.3) associated with lower CSF β-amyloid_42/40 and CSF β-amyloid₄₂/phosphorylated tau181 in the whole sample and specifically in the SCD subgroup.

CONCLUSIONS

Within the spectrum of clinically unimpaired (i.e., before mild cognitive impairment) cognitive performance, SCD is associated with minor deficits in memory, executive function, and language abilities. The association of these subtle cognitive deficits with AD CSF biomarkers speaks to their validity and potential use for the early detection of underlying preclinical AD.

Refining the metamemory in adulthood questionnaire: a 20-item version of change and capacity designed for research and clinical settings

Objective: Subjective memory concerns (SMCs) might be an early indicator of future cognitive decline and conversion to dementia. However, a rich history of mixed findings, moderating factors, and heterogenous methods preclude the usefulness of SMCs in both research and clinical settings. The present study aimed to review some of the factors that might cause mixed results and propose a revised version the Metamemory in Adulthood (MIA) Questionnaire that can be easily implemented to more consistently derive estimates of SMCs.Method: We used factor analysis and regression to investigate the utility of a revised 20-item version of the MIA Change and Capacity subscales.Results: Based on two samples of older adults (N = 382 and N = 221), the revised scale showed strong internal reliability and a two-factor structure. Regression analyses supported the incremental validity of the MIA-Revised Change scale in predicting performance on the Rivermead Behavioural Memory Test.Conclusions: By establishing a revised version of a well-known and previously validated questionnaire to assess SMCs, research and clinics can better implement a psychometrically sound measure quickly and easily. Moreover, the revised Change and Capacity subscales provide sufficient divergence to be sensitive to different facets of SMCs in a community dwelling older adult sample.

Subjective Cognitive Decline Below and Above the Age of 60: A Multivariate Study on Neuroimaging, Cognitive, Clinical, and Demographic Measures

Subjective cognitive complaints in cognitively normal individuals are a relevant predictor of Alzheimer's disease (AD), cerebrovascular disease, and age-related tauopathy. Complaints starting after the age of 60 increase the likelihood of preclinical AD. However, this criterion is arbitrary and current data show that neurodegenerative disorders likely start before that age. Further, data on the role of subjective complaints below the age of 60 in individuals qualifying for subjective cognitive decline (SCD) are lacking. We investigated the association of subjective cognitive complaints with an extensive number of neuroimaging, demographic, clinical, and cognitive measures in individuals fulfilling criteria for SCD below and above the age of 60. Nine complaints were scored in 416 individuals. Complaints were related to a higher load of white matter signal abnormalities, and this association was stronger the more subclinical changes in personality, interest, and drive were reported. In individuals <60 years, complaints were associated with lower global cognitive performance. In individuals ≥60 years, complaints were related to greater global brain atrophy and smaller total intracranial volume, and this association was stronger the more subclinical difficulties in activities of daily living were reported. Also, complaints were associated with increased depressive symptomatology irrespective of age. We conclude that complaints below the age of 60 may be associated with subtle signs of brain pathology. In the community, screening for risk of future cognitive decline should include subjective cognitive complaints, depressive symptomatology, and subclinical reduced cognition (<60 years)/activities of daily living (≥60 years), supported by basic neuroimaging examinations.

Influence of apolipoprotein-E genotype on brain amyloid load and longitudinal trajectories

To characterize the influence of apolipoprotein-E (APOE) genotype on cerebral Aβ load and longitudinal Aβ trajectories, [¹¹C]Pittsburgh compound-B (PiB) positron emission tomography (PET) imaging was used to assess amyloid load in a clinically heterogeneous cohort of 428 elderly participants with known APOE genotype. Serial [¹¹C]PiB data and a repeated measures model were used to model amyloid trajectories in a subset of 235 participants classified on the basis of APOE genotype. We found that APOE-ε4 was associated with increased Aβ burden and an earlier age of onset of Aβ positivity, whereas APOE-ε2 appeared to have modest protective effects against Aβ. APOE class did not predict rates of Aβ accumulation. The present study suggests that APOE modifies Alzheimer's disease risk through a direct influence on amyloidogenic processes, which manifests as an earlier age of onset of Aβ positivity, although it is likely that other genetic, environmental, and lifestyle factors are important.

Longitudinal study of self-reported hearing loss and subjective cognitive function decline in women

INTRODUCTION

We investigated the relation between self-reported hearing loss and risk of subjective cognitive function (SCF) decline among women.

METHODS

We conducted a longitudinal study of 20,193 women in the Nurses' Health Study aged ≥66 years who reported their hearing status and had no subjective cognitive concerns in 2012. SCF scores were assessed by a 7-item questionnaire in 2012 and 2014. SCF decline was defined as a new report of at least one cognitive concern during follow-up.

RESULTS

Self-reported hearing loss was associated with higher risk of SCF decline. Compared with women with no hearing loss, the multivariable-adjusted odds ratios (95% confidence interval) for incident SCF score ≥1 were 1.35 (1.25, 1.47), 1.39 (1.24, 1.56), and 1.40 (1.21, 1.75) among women with mild, moderate, and severe hearing loss, respectively. Recent progression of hearing loss was associated with even higher risk.

DISCUSSION

Self-reported hearing loss was associated with higher risk of incident subjective cognitive function decline in women.

White Matter Microstructural Damage as an Early Sign of Subjective Cognitive Decline

Background and Objective: Subjective cognitive decline (SCD) is considered a preclinical state of Alzheimer's disease (AD) and may represent a more advanced preclinical status than amnestic mild cognitive impairment (aMCI). Our aim was to explore changes in the white matter (WM) microstructure and their correlation with cognitive function in these AD-spectrum patients. Methods: Diffusion tensor images from 43 individuals with normal cognition (NC), 38 SCD patients, and 36 aMCI patients were compared using an atlas-based segmentation strategy. The correlation between diffusion parameters and cognitive function was further analyzed. Results: The anatomical pattern of WM impairment was generally similar between SCD and aMCI patients. However, aMCI patients showed significantly lower fractional anisotropy (i.e., corpus callosum forceps major and forceps minor) and increased mean diffusivity [i.e., bilateral anterior thalamic radiation (ATR), left corticospinal tract (CST), forceps minor, left cingulum (cingulate gyrus), left cingulum hippocampus, and left inferior fronto-occipital fasciculus (IFO)] in some tracts than did SCD subjects, indicating a disruption in WM microstructural integrity in the aMCI. Individuals with microstructural disruption in forceps minor, left cingulum (cingulate gyrus), and left cingulum hippocampus tracts performed worse in general cognition and memory function tests, as indicated by line regression analysis. Conclusion: SCD individuals had extensive WM microstructural damage in a pattern similar to that seen in aMCI, although presenting a cognitive performance comparable with that of cognitively healthy individuals. Our results suggest that WM integrity might precede objectively measurable memory decline and may be a potential early biomarker for AD.

L1CAM Beneficially Inhibits Histone Deacetylase 2 Expression under Conditions of Alzheimer's Disease

BACKGROUND

Cognitive capacities in Alzheimer's Disease (AD) are impaired by an epigenetic blockade mediated by histone deacetylase 2 (HDAC2), which prevents the transcription of genes that are important for synaptic plasticity.

OBJECTIVE

Investigation of the functional relationship between cell adhesion molecule L1 and HDAC2 in AD.

METHODS

Cultures of dissociated cortical and hippocampal neurons from wild-type or L1-deficient mice were treated with Aβ1-42 for 24 h. After removal of Aβ1-42 cells were treated with the recombinant L1 extracellular domain (rL1) for 24 h followed by immunohistochemistry, western blotting, and reverse transcription PCR to evaluate the interaction between L1 and HDAC2.

RESULTS

Aβ and HDAC2 protein levels were increased in APPSWE/L1+/- mutant brains compared to APPSWE mutant brains. Administration of the recombinant extracellular domain of L1 to cultured cortical and hippocampal neurons reduced HDAC2 mRNA and protein levels. In parallel, reduced phosphorylation levels of glucocorticoid receptor 1 (GR1), which is implicated in regulating HDAC2 levels, was observed in response to L1 administration. Application of a glucocorticoid receptor inhibitor reduced Aβ-induced GR1 phosphorylation and prevented the increase in HDAC2 levels. HDAC2 protein levels were increased in cultured cortical neurons from L1-deficient mice. This change could be reversed by the administration of the recombinant extracellular domain of L1.

CONCLUSION

Our results suggest that some functionally interdependent activities of L1 and HDAC2 contribute to ameliorating the phenotype of AD by GR1 dephosphorylation, which leads to reduced HDAC2 expression. The combined findings encourage further investigations on the beneficial effects of L1 in the treatment of AD.

Using subjective cognitive decline to identify high global amyloid in community-based samples: A cross-cohort study

INTRODUCTION

We aimed to examine the contribution of subjective cognitive decline (SCD) to reduce the number of β-amyloid (Aβ) positron emission tomography scans required for recruiting Aβ+ clinically normal individuals in clinical trials.

METHODS

Three independent cohorts (890 clinically normal: 72 yrs ± 6.7; Female: 43.4%; SCD+: 24%; apolipoprotein E [APOE] ε4+: 28.5%; Aβ+: 32%) were used. SCD was dichotomized from one question. Using logistic regression, we classified Aβ+ using the SCD dichotomy, APOEε4, sex, and age.

RESULTS

SCD increased odds of Aβ+ by 1.58 relative to non-SCD. Female APOEε4 carriers with SCD exhibited higher odds of Aβ+ (OR = 3.34), whereas male carriers with SCD showed a weaker, opposing effect (OR = 0.37). SCD endorsement reduces the number of Aβ positron emission tomography scans to recruit Aβ+ individuals by 13% and by 9% if APOEε4 status is known.

CONCLUSION

SCD helps to classify those with high Aβ, even beyond the substantial effect of APOE genotype. Collecting SCD is a feasible method for targeting recruitment for those likely on the AD trajectory.

Biomarker-Based Signature of Alzheimer's Disease in Pre-MCI Individuals

Alzheimer’s disease (AD) pathology begins decades before the onset of clinical symptoms. It is recognized as a clinicobiological entity, being detectable in vivo independently of the clinical stage by means of pathophysiological biomarkers. Accordingly, neuropathological studies that were carried out on healthy elderly subjects, with or without subjective experience of cognitive decline, reported evidence of AD pathology in a high proportion of cases. At present, mild cognitive impairment (MCI) represents the only clinically diagnosed pre-dementia stage. Several attempts have been carried out to detect AD as early as possible, when subtle cognitive alterations, still not fulfilling MCI criteria, appear. Importantly, pre-MCI individuals showing the positivity of pathophysiological AD biomarkers show a risk of progression similar to MCI patients. In view of successful treatment with disease modifying agents, in a clinical setting, a timely diagnosis is mandatory. In clinical routine, biomarkers assessment should be taken into consideration whenever a subject with subtle cognitive deficits (pre-MCI), who is aware of his/her decline, requests to know the cause of such disturbances. In this review, we report the available neuropsychological and biomarkers data that characterize the pre-MCI patients, thus proposing pre-MCI as the first clinical manifestation of AD.

Subjective Cognitive Decline and APOE ɛ4: A Systematic Review

Individuals with subjective cognitive decline (SCD) report self-perceived declines in cognitive function but perform within normal limits on standardized tests. However, for some, these self-perceived changes may herald eventual decline to Alzheimer's disease (AD). In light of this, the relationship between SCD and APOE ɛ4, a known genetic risk factor for AD, has garnered interest; however, no systematic review of this literature exists. The current review (n = 36 articles) examined the prevalence of APOE ɛ4 in SCD samples relative to healthy and objectively impaired samples, and summarized APOE ɛ4-related risk of conversion from SCD to AD. Univariate ANOVA indicated that APOE ɛ4 frequency was comparable between healthy control and SCD samples, yet significantly higher in objectively impaired samples (i.e., MCI, AD) relative to either of these groups. Narrative review provided mixed evidence linking coincident APOE ɛ4-positive genotype and SCD to structural neuropathology. Though there was little evidence to suggest that APOE ɛ4 predisposes individuals to developing SCD, both APOE ɛ4 and SCD were found to confer individual and multiplicative risk of conversion to objective cognitive impairment. Combined, it is likely that a relationship between APOE ɛ4, SCD, and AD exists, though its exact nature remains undetermined. A clearer understanding of these relationships is hindered by a lack of standardization in SCD classification and a dearth of longitudinal outcome research. Wide-scale adoption of genetic screening for dementia risk in persons with SCD is considered premature at this time. Ethical considerations and clinical implications of genetic testing for dementia risk are discussed.