A conceptual framework for research on subjective cognitive decline in preclinical Alzheimer's disease

What is autonoetic consciousness? Examining what underlies subjective experience in memory and future thinking

Autonoetic consciousness is the awareness that an event we remember is one that we ourselves experienced. It is a defining feature of our subjective experience of remembering and imagining future events. Given its subjective nature, there is ongoing debate about how to measure it. Our goal was to develop a framework to identify cognitive markers of autonoetic consciousness. Across two studies (N = 342) we asked young, healthy participants to provide written descriptions of two autobiographical memories, two plausible future events, and an experimentally encoded video. Participants then rated their subjective experience during remembering and imagining. Exploratory Factor Analysis of this data uncovered the latent variables underlying autonoetic consciousness across these different events. In contrast to work that emphasizes the distinction between Remember and Know as being key to autonoetic consciousness, Re-experiencing, and Pre-experiencing for future events, were consistently identified as core markers of autonoetic consciousness. This was alongside Mental Time Travel in all types of memory events, but not for imagining the future. In addition, our factor analysis allows us to demonstrate directly - for the first time - the features of mental imagery associated with the sense of autonoetic consciousness in autobiographical memory; vivid, visual imagery from a first-person perspective. Finally, with regression analysis, the emergent factor structure of autonoetic consciousness was able to predict the richness of autobiographical memory texts, but not of episodic recall of the encoded video. This work provides a novel way to assess autonoetic consciousness, illustrates how autonoetic consciousness manifests differently in memory and imagination and defines the mental representations intrinsic to this process.

Association Between Clonal Hematopoiesis of Indeterminate Potential and Brain β-Amyloid Deposition in Korean Patients With Cognitive Impairment

Few studies have focused on the association between clonal hematopoiesis of indeterminate potential (CHIP) and β-amyloid (Aβ) deposition in the brain, which causes Alzheimer's disease. We aimed to investigate the potential role of CHIP in brain Aβ deposition in Korean patients. We enrolled 58 Korean patients over 50 yrs of age with cognitive impairment who underwent brain Aβ positron emission tomography. We explored CHIP in their peripheral blood using deep-targeted next-generation sequencing. Irrespective of the presence or absence of brain Aβ deposition, mutations in DNMT3A and the C:G>T:A single-nucleotide variants were identified as the primary characteristics, which reflect aged hematopoiesis in the study population. Multivariate logistic regression revealed that the presence of CHIP was not associated with brain Aβ deposition. As both CHIP and brain Aβ deposition are associated with aging, further research is required to elucidate their possible interplay.

Forgetting rate for the familiarity and recollection components of recognition in amnestic mild cognitive impairment: A longitudinal study

Here we aimed to investigate the rate of forgetting of the familiarity and recollection components of recognition in patients at the onset of medial temporal lobe (MTL) pathology and destined to convert to Alzheimer's disease (AD). For this purpose, we conducted a longitudinal study of 13 patients who were diagnosed with amnestic mild cognitive impairment (a-MCI) at the first assessment and followed-up for 3 years. During this time, five patients converted to AD and eight remained in a stable condition of cognitive impairment. A group of 15 healthy subjects were enrolled as the control group (HC). In order to separately quantify the contribution of recollection and familiarity to recognition memory performance, the experimental sample was submitted to a modified version of Huppert and Piercy's procedure that included a Remember/Know paradigm. Data demonstrated that both stable and converter a-MCI patients forgot memory traces relative to the familiarity components of recognition at the same rate as HC. Conversely, converter a-MCI patients showed accelerated long-term forgetting specifically for the recollection component of recognition compared to stable a-MCI and HC. This is the first empirical demonstration that familiarity and recollection components of declarative memory are subject to different rates of forgetting in a-MCI patients as a function of their longitudinal clinical outcome. Our finding of accelerated long-term forgetting of the recollection component of recognition disclosed by converter a-MCI patients suggests that atrophy in the MTL not only interferes with the storage aspects but also disrupts the consolidation of memory traces.

Association of Neurogranin and BACE1 With Clinical Cognitive Decline in Individuals With Subjective Cognitive Decline

BACKGROUND AND OBJECTIVES

CSF biomarkers have immense diagnostic and prognostic potential for Alzheimer disease (AD). However, AD is still diagnosed relatively late in the disease process, sometimes even years after the initial manifestation of cognitive symptoms. Thus, further identification of biomarkers is required to detect related pathology in the preclinical stage and predict cognitive decline. Our study aimed to assess the association of neurogranin and β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) with cognitive decline in individuals with subjective cognitive decline (SCD).

METHODS

We enrolled participants with available neurogranin and BACE1 measurements in CSF from the DELCODE (DZNE-Longitudinal Cognitive Impairment and Dementia, Germany) cohort. The longitudinal change of Preclinical Alzheimer's Cognitive Composite score was assessed as the primary outcome in participants with SCD and controls. The secondary outcome was defined as conversion of SCD to mild cognitive impairment (MCI) during follow-up. Levels of neurogranin, BACE1, and neurogranin/BACE1 ratio across groups were compared by analysis of covariance after adjustment for demographics. The linear mixed-effects model and Cox regression analysis were applied to evaluate their association with cognitive decline and progression of SCD to MCI, respectively.

RESULTS

A total of 530 participants (mean age: 70.76 ± 6.01 years, 48.7% female) were analyzed in the study. The rate of cognitive decline was faster in individuals with SCD with higher neurogranin and neurogranin/BACE1 ratio (β = -0.138, SE = 0.065, p = 0.037, and β = -0.293, SE = 0.115, p = 0.013). Higher baseline neurogranin and neurogranin/BACE1 ratio were associated with an increased rate of conversion from SCD to MCI (hazard ratio [HR] 1.35 per SD, 95% CI 1.03-1.77, p = 0.028, and HR 1.53 per SD, 95% CI 1.13-2.07, p = 0.007). In addition, the impact of higher neurogranin levels on accelerating the rate of cognitive decline was more pronounced in the SCD group than in cognitively unimpaired controls (β = -0.077, SE = 0.033, p = 0.020).

DISCUSSION

Our findings suggest that CSF neurogranin and BACE1 begin to change in the preclinical stage of AD and they are associated with clinical progression in individuals with SCD.

Impacts of subjective cognitive decline and mild cognitive impairment on the effectiveness of an exercise intervention among community-dwelling (Pre)frail older adults

BACKGROUND

Subjective cognitive decline (SCD) is prevalent in community-dwelling (pre)frail older adults. This study aimed to investigate whether baseline subjective cognitive decline (SCD) and mild cognitive impairment (MCI) impacted the effectiveness of an exercise intervention among (pre)frail older adults.

METHODS

This is a post hoc analysis of a stepped-wedge cluster randomized trial among (pre)frail older adults across six communities. The intervention effectiveness was examined among (pre)frail older people among subgroups with normal cognition (n = 44), SCD (n = 58), or MCI (n = 30).

RESULTS

The normal cognition group had both immediate and persistent treatment responses to most outcomes. The SCD group showed positive responses to frailty (0-, 12-, 24 week), ambulation and dynamic balance (0-week), and depressive symptoms (12-week). The MCI group exhibited immediate improvement in frailty, cognition, depressive symptoms, social support and QoL, which persisted only in frailty status, social support and mental QoL at follow-ups. The MCI group showed superior immediate responses to cognitive function and depressive symptoms compared to another two subgroups. No differences were found between the normal cognition and SCD groups except for cognitive status (12-week).

CONCLUSIONS

(Pre)frail people with SCD or MCI had fewer improved outcomes compared to those with normal cognition regardless of immediate or persistent improvements. The incorporation of cognitive strategies with exercise interventions are recommended among (pre)frail older adults with SCD or MCI.

Socioeconomic and medical determinants of state-level subjective cognitive decline in the United States

INTRODUCTION

It is important to understand the socioeconomic and medical determinants of subjective cognitive decline (SCD) at a population level in the United States.

METHODS

The primary outcomes are state-level rates of SCD and SCD-related functional impairment in adults aged ≥ 45, both measured in the Behavioral Risk Factor Surveillance System from 2016 to 2022. The exposures are state-level rates of poverty, unemployment, homelessness, college education, racial and ethnic minorities, uninsurance, smoking, hypertension, diabetes, and obesity as well as household income and physician density.

RESULTS

The strongest state-level associations with rates of SCD were the prevalence of diabetes (rho = 0.64), hypertension (rho = 0.59), and poverty (rho = 0.58; all p < 0.001), and with SCD-related functional impairment were prevalence of poverty (rho = 0.71), diabetes (rho = 0.68), and hypertension (rho = 0.53; all p < 0.001).

DISCUSSION

This study highlights critical links between SCD and socioeconomic and medical determinants in adults aged ≥ 45 in the United States, including the prevalence of poverty, diabetes, and hypertension.

HIGHLIGHTS

State-level analysis reveals socioeconomic and medical risk factors for subjective cognitive decline (SCD) at a population level. The prevalence of poverty is a critical contributor to the state-level prevalence of SCD. The prevalence of diabetes and hypertension are also strong state-level determinants of SCD. Addressing the burden of cognitive decline at the population level necessitates targeting socioeconomic and medical factors.

Subjective Cognitive Decline Plus and Longitudinal Assessment and Risk for Cognitive Impairment

Importance

Subjective cognitive decline (SCD) is recognized to be in the Alzheimer disease (AD) cognitive continuum. The SCD Initiative International Working Group recently proposed SCD-plus (SCD+) features that increase risk for future objective cognitive decline but that have not been assessed in a large community-based setting.

Objective

To assess SCD risk for mild cognitive impairment (MCI), AD, and all-cause dementia, using SCD+ criteria among cognitively normal adults.

Design, Setting, and Participants

The Framingham Heart Study, a community-based prospective cohort study, assessed SCD between 2005 and 2019, with up to 12 years of follow-up. Participants 60 years and older with normal cognition at analytic baseline were included. Cox proportional hazards (CPH) models were adjusted for baseline age, sex, education, APOE ε4 status, and tertiles of AD polygenic risk score (PRS), excluding the APOE region. Data were analyzed from May 2021 to November 2023.

Exposure

SCD was assessed longitudinally using a single question and considered present if endorsed at the last cognitively normal visit. It was treated as a time-varying variable, beginning at the first of consecutive, cognitively normal visits, including the last, at which it was endorsed.

Main Outcomes and Measures

Consensus-diagnosed MCI, AD, and all-cause dementia.

Results

This study included 3585 participants (mean [SD] baseline age, 68.0 [7.7] years; 1975 female [55.1%]). A total of 1596 participants (44.5%) had SCD, and 770 (21.5%) were carriers of APOE ε4. APOE ε4 and tertiles of AD PRS status did not significantly differ between the SCD and non-SCD groups. MCI, AD, and all-cause dementia were diagnosed in 236 participants (6.6%), 73 participants (2.0%), and 89 participants (2.5%), respectively, during follow-up. On average, SCD preceded MCI by 4.4 years, AD by 6.8 years, and all-cause dementia by 6.9 years. SCD was significantly associated with survival time to MCI (hazard ratio [HR], 1.57; 95% CI, 1.22-2.03; P <.001), AD (HR, 2.98; 95% CI, 1.89-4.70; P <.001), and all-cause dementia (HR, 2.14; 95% CI, 1.44-3.18; P <.001). After adjustment for APOE and AD PRS, the hazards of SCD were largely unchanged.

Conclusions and Relevance

Results of this cohort study suggest that in a community setting, SCD reflecting SCD+ features was associated with an increased risk of future MCI, AD, and all-cause dementia with similar hazards estimated in clinic-based settings. SCD may be an independent risk factor for AD and other dementias beyond the risk incurred by APOE ε4 and AD PRS.

Concurrent Validity of Performance-Based Measures of Daily Functioning with Cognitive Measures and Informant Reported Everyday Functioning

OBJECTIVE

Despite the substantial need for reliable and valid assessment of functional ability in older adults, there is currently limited research on the emergence of early functional declines during prodromal dementia stages, such as subjective cognitive decline (SCD) and mild cognitive impairment (MCI). This study uses novel performance-based assessments to characterize subtle, yet clinically meaningful, changes in functional ability.

METHOD

A sample of 93 older adults classified as cognitively unimpaired (CU; n = 30, Mage = 73.57 ± 6.66), SCD (n = 34, Mage = 72.56 ± 6.43), or MCI (n = 29, Mage = 78.28 ± 7.55) underwent neuropsychological testing along with an informant-rated daily functional skills measure (Assessment of Functional Capacity Interview). Participants also completed the Night Out Task (NOT), an open-ended performance-based measure of functional assessment, and the Financial Capacity Instrument-Short Form (FCI-SF) that assesses financial skills.

RESULTS

The MCI group performed worse on the NOT and FCI-SF relative to SCD and CU. NOT and FCI scores were associated with measures of global cognitive function, executive function, processing speed, language and memory, and FCI-SF overall score was correlated with informant-rated functional ability. The NOT and FCI-SF were also predictive of informant-reported daily functioning over and above traditional cognitive data and demographics.

CONCLUSIONS

Performance-based measures of IADL may allow for earlier detection of subtle functional changes that might not be adequately captured by traditional measures. The measurement of early functional changes is an important global outcome to evaluate the efficacy of interventions in dementia research.

The role and mechanism of dapagliflozin in Alzheimer disease: A review

Alzheimer disease (AD), as the main type of dementia, is primarily characterized by cognitive dysfunction across multiple domains. Current drugs for AD have not achieved the desired clinical efficacy due to potential risks, inapplicability, high costs, significant side effects, and poor patient compliance. However, recent findings offer new hope by suggesting that sodium-glucose cotransporter 2 inhibitors (SGLT-2i) may possess neuroprotective properties, potentially opening up novel avenues for the treatment of AD. This review delves deeply into the multifaceted mechanisms of action of SGLT-2i in AD, encompassing antioxidative stress, antineuroinflammation, upregulation of autophagy, antiapoptosis, acetylcholinesterase inhibitor activity, and protection of endothelial cells against atherosclerosis and damage to the blood-brain barrier, among others. Furthermore, it provides an overview of recent advances in clinical research on this drug. These findings suggest that SGLT-2i is poised to emerge as a pivotal candidate for the treatment of AD, given its diverse functional effects.

Associations between the multitrajectory neuroplasticity of neuronavigated rTMS-mediated angular gyrus networks and brain gene expression in AD spectrum patients with sleep disorders

INTRODUCTION

The multifactorial influence of repetitive transcranial magnetic stimulation (rTMS) on neuroplasticity in neural networks is associated with improvements in cognitive dysfunction and sleep disorders. The mechanisms of rTMS and the transcriptional-neuronal correlation in Alzheimer's disease (AD) patients with sleep disorders have not been fully elucidated.

METHODS

Forty-six elderly participants with cognitive impairment (23 patients with low sleep quality and 23 patients with high sleep quality) underwent 4-week periods of neuronavigated rTMS of the angular gyrus and neuroimaging tests, and gene expression data for six post mortem brains were collected from another database. Transcription-neuroimaging association analysis was used to evaluate the effects on cognitive dysfunction and the underlying biological mechanisms involved.

RESULTS

Distinct variable neuroplasticity in the anterior and posterior angular gyrus networks was detected in the low sleep quality group. These interactions were associated with multiple gene pathways, and the comprehensive effects were associated with improvements in episodic memory.

DISCUSSION

Multitrajectory neuroplasticity is associated with complex biological mechanisms in AD-spectrum patients with sleep disorders.

HIGHLIGHTS

This was the first transcription-neuroimaging study to demonstrate that multitrajectory neuroplasticity in neural circuits was induced via neuronavigated rTMS, which was associated with complex gene expression in AD-spectrum patients with sleep disorders. The interactions between sleep quality and neuronavigated rTMS were coupled with multiple gene pathways and improvements in episodic memory. The present strategy for integrating neuroimaging, rTMS intervention, and genetic data provide a new approach to comprehending the biological mechanisms involved in AD.

Subjective Cognitive Decline is associated with altered patterns of brain activity and connectivity during performance of an old/new recognition memory task

INTRODUCTION

Subjective Cognitive Decline (SCD) is considered a preclinical stage within the AD continuum. Knowledge about the functional changes in the brain associated with episodic memory retrieval and novelty recognition in people with SCD is currently very limited.

METHOD

The study aimed to evaluate behavioural and neurofunctional changes in individuals with SCD, measured relative to a control group, during successful episodic memory retrieval and novelty recognition, as well as to compare the functional connectivity patterns related to these cognitive processes within the Default Mode Network (DMN) in both groups. Participants performed an old/new recognition memory task with words while the BOLD signal was acquired.

RESULTS

No between-group differences were observed in the performance of the episodic memory task. However, during the successful recognition of old words, the SCD group showed brain hypoactivity in the right rolandic operculum and reduced functional connectivity between the DMN and the fronto-parietal control network (FPCN). During the correct identification of new words, the SCD group also showed reduced connectivity between the DMN and the FPCN, and lower connectivity within the DMN.

CONCLUSION

Despite the absence of objective evidence of cognitive impairment, people with SCD display several changes in brain activity and connectivity associated with episodic memory retrieval and novelty recognition.

Gender differences in neurocognitive assessments: insights from a pilot study with the International Neurocognitive Test Profile (INCP) digital battery

BACKGROUND

The aging global population has led to an increase in the number of dementia diagnoses, with projections indicating a continued upward trend. This demographic change presents profound challenges for patients, their families, and healthcare systems worldwide. Consequently, the demand for reliable and user-friendly screening tools that can detect dementia at early stages and monitor its progression is more critical than ever. The International Neurocognitive Test Profile (INCP), developed at the Medical University of Vienna, aims to address this need by offering a digital test battery for the early detection of dementia. This study forms a part of the INCP's ongoing development and evaluation, specifically investigating the influence of gender on test outcomes.

METHODS

Seventy participants, recruited through flyers at the Vienna General Hospital, completed the INCP assessment using tablets as part of the study. The effect of gender on performance across various INCP subtests was analyzed using Mann-Whitney U tests. For further exploratory analysis, a correlation matrix was calculated encompassing demographic variables (age and education), screening data, and all INCP subtests.

RESULTS

The analysis revealed significant gender differences in two INCP subtests related to executive functions. Males outperformed females on the Figure Fluency Test (r = 0.30, indicating a moderate effect) and the Dice 2‑n Back Test (r = 0.29, indicating a small effect). However, when correcting for multiple comparisons, no significant gender disparities were observed in the scores of the subtests.

CONCLUSION

The identification of possible gender differences in specific subtests underscores the importance of considering gender as a variable in the further development and evaluation of the INCP. These findings offer valuable insights for the design and planning of future studies involving the INCP.

Effects of Rehabilitation Training on Cognitive Function in Parkinson's Disease with Subjective Cognitive Decline

Purpose

To characterize Subjective Cognitive Decline (SCD) in Parkinson's disease (PD) and its progression, as well as to assess the impact of rehabilitation training programs on cognitive function in PD patients.

Patients and Methods

The study involved 42 patients diagnosed with PD. Participants underwent evaluation using a neuropsychological protocol and were subsequently classified into two groups: those with SCD (PD-SCD+, n= 22) or those without (PD-SCD-, n= 20). After an average follow-up period of 3.0 years (2.7-4.6 years), cognitive assessments were reiterated with the same group of subjects. Following the re-assessment, all 42 patients participated in a six-month rehabilitation training program, concluding with the reevaluation of cognitive performance.

Results

In the follow-up assessment, it was observed that PD-SCD+ experienced a more pronounced annual decline in cognitive function, as measured by the Chinese-Beijing version of Montreal Cognitive Assessment (BJ-MoCA) test and semantic fluency, compared to PD-SCD-. A stepwise logistic regression analysis identified low MMSE scores (P< 0.001), elevated HAMD scores (P= 0.008), male gender (P= 0.026), and the presence of SCD (P= 0.022) associated with diminished language skills in PD patients. Both groups of PD patients exhibited improvements in BJ-MoCA scores after participating a six-month rehabilitation training program. Particularly notable is the statistically significant improvement in language skills observed in patients with PD-SCD+ compared to PD-SCD- patients following rehabilitation training.

Conclusion

As PD progresses, individuals with PD-SCD+ tend to experience more pronounced cognitive decline compared to those with PD-SCD-. Semantic fluency emerges as a crucial component for assessing the cognitive subset of PD, potentially serving as an indicator of cognitive decline in individuals with PD. Evidence suggests that rehabilitation training is a viable intervention for individuals diagnosed with PD. This intervention not only improves various cognitive domains but also leads to more substantial enhancements in language skills.

Tipping the Balance Between Cognitive Reserve, Frailty, and Dementia in the Very Old?

Background

As the population ages, the concept of frailty becomes increasingly relevant and may be considered a precursor between aging and the development of dementia in later life. Similarly, the construct of cognitive reserve (CR) is an accepted model of cognitive resilience that may account for individual differences in trajectories of brain aging, mitigating the clinical expression of dementia.

Objective

We aim to estimate the role of CR and frailty in moderating the prediction of dementia in the population aged over 80 who are attending an Italian outpatient memory clinic.

Methods

Comprehensive Geriatric Assessment, Clinical Frailty Scale (CFS) to screen for frailty, and Cognitive Reserve Index questionnaire (CRIq) to evaluate CR, were used to assess patients systematically. We performed multivariate logistic regression to assess associations with dementia. Model performance and interaction between frailty and cognitive reserve were then evaluated.

Results

166 patients were consecutively enrolled (mean age was 85.7 years old, females composed 68%); 25% had a diagnosis of amnestic mild cognitive impairment, and 75% had a diagnosis of dementia. Multivariate regression analysis showed that CRIq and CFS were the main clinical assessment tools associated with the presence of dementia, even after collinearity adjustment. No significant interaction of CFS*CRIq was found.

Conclusions

To our knowledge, this is the first study to investigate the association between CR, frailty, dementia, and their related interacting terms in a real-world population of very old patients. Our findings may suggest that both CR and frailty shape an individual's resilience throughout their lifetime. This may potentially counteract the effects of brain neuropathology, in line with the hypothesis that meaningful associations exist between CR, frailty, and cognition in later life.

Increased reliance on heuristic thinking in mild cognitive impairment

Reasoning can be fast, automatic, and intuitive or slow, deliberate, and analytical. Use of one cognitive reasoning style over the other has broad implications for beliefs, but differences in cognitive style have not previously been reported in those with mild cognitive impairment (MCI). Here, the cognitive reflection test is used to measure cognitive style in healthy older adults and those with MCI. Those with MCI performed worse than cognitively healthy older adults, indicating they are more likely to engage in intuitive thinking than age-matched adults. This association is reliable after controlling for additional cognitive, self-report, and demographic factors. Across all measures, subjective cognitive decline was the best predictor of cognitive status. A difference in cognitive style represents a novel behavioral marker of MCI, and future work should explore whether this explains a broader pattern of reasoning errors in those with MCI, such as susceptibility to scams or impaired financial reasoning.

Association between Multi-Domain Lifestyle and Objective Cognitive Impairment in Elderly People with SCD and MCI in Chinese Communities

OBJECTIVES

Controlling the lifestyle associated with dementia risk can delay the process of cognitive decline. Subjective cognitive decline (SCD) and mild cognitive impairment (MCI) are early states in the development of dementia and are also the window period for early intervention in dementia. The purpose of this study was to explore the association between multi-domain lifestyle and objective cognitive impairment in elderly people with SCD and MCI in Chinese communities and to provide reference for effective implementation of precise health management measures to reduce the risk of dementia.

METHODS

A total of 265 middle-aged and elderly volunteers recruited from the community were divided into SCD group (107 cases), MCI group (80 cases), and healthy control (HC) group (78 cases). All participants received clinical interview, examination, and cognitive assessments.

RESULTS

The total Dementia Risk Reduction Lifestyle Scale (DRRLS) scores in the HC, SCD, and MCI groups [110.00 (11.25) vs. 101.00 (10.00) vs. 79.50 (20.75)] exhibited statistically significant differences among them. The total score of the DRRLS showed a significant negative correlation with the Trail-Making Test (TMT), and significant positive correlations with both the Verbal Fluency Test (VFT) and Auditory Verbal Learning Test (AVLT) scores (p < 0.05). After adjusting for confounding factors, such as age and years of education, multiple linear regression analysis revealed several points. In the SCD group, brain-strengthening exercise and interpersonal relationship scores were negatively correlated with TMT scores (β = -11.257, -15.077; all p < 0.05), while health responsibility, smoking control behavior, and interpersonal relationship scores were positively correlated with AVLT scores (β = 0.485, 0.344, and 0.406; all p < 0.05). In the MCI Group, brain-strengthening exercise, brain-healthy diet, and interpersonal relationship were negatively correlated with TMT (β = -22.011, -16.206, -11.696; all p < 0.01), whereas health responsibility, mental activity, smoking control behavior, interpersonal relationship, and stress management were positively correlated with AVLT (β = 0.450, 0.435, 0.308, 0.256, 0.607; all p < 0.05).

CONCLUSIONS

In Chinese communities, the unhealthy lifestyle of elderly individuals with SCD and MCI is significantly associated with cognitive function impairment. The greater their unhealthy lifestyle habits, the more pronounced the scope and severity of cognitive function impairment becomes. Furthermore, different dimensions of lifestyle have varying impacts on cognitive domains.

Olfaction and thyroid hormones in patients with subjective cognitive decline, non-amnestic and amnestic mild cognitive impairment

BACKGROUND

Thyroid hormones may affect olfaction in different stages of cognitive impairment: subjective cognitive decline (SCD), non-amnestic (naMCI) and amnestic mild cognitive impairment (aMCI). Additionally, biometric parameters, depression, and neuropsychological performance are considered as possible influencing factors.

DESIGN AND PATIENTS

A retrospective single-center data analysis was conducted during the observation period 2001-2023, with n = 495 (52.3% female) SCD, naMCI and aMCI subjects, aged ≥50 years, at the General Hospital of Vienna.

MEASUREMENTS

The criterion olfactory function was objectively measured by Sniffin' Sticks© odor identification and subjectively through the Assessment of Self-Reported Olfactory Functioning test. Serum thyroid hormone levels, mainly thyroid-stimulating hormone, as well as T3, T4, fT3, and fT4, were used to assess thyroid function. Statistical analyses using IBM SPSS® 29.0.0 covered adjusted multiple linear regression models with hierarchical blocks to predict olfactory performance considering β‑weights.

RESULTS

Of the study participants, 4.2% had hypothyroidism and 2.4% had hyperthyroidism. The majority exhibited normal thyroid function. One third (33.5%; 95% confidence interval, CI 29.4-37.0%) were hyposmic. The results indicate no substantial association between thyroid and olfactory functions. Increasing age (β = 0.20), lower performance in the Neuropsychological Test Battery Vienna (NTBV) dimensions verbal memory (β = -0.33) and attention (β = -0.12) appear to be risk factors for lower olfaction. A discrepancy between subjective and objective olfaction was found.

CONCLUSION

Thyroid and olfactory functions had no substantial relationship. Higher fT4 correlated weakly with lower odor identification. Increasing age and decreased performance in two out of six NTBV dimensions are relevant prognostic factors for olfactory dysfunction.

Neuropsychological Correlates of Clinical Progression in Subjective Cognitive Decline

Background

Subjective cognitive decline (SCD) refers to self-reported cognitive decline in individuals with normal performance on standardized cognitive tests. Understanding the factors predicting progression from SCD to mild cognitive impairment (MCI) is crucial, as approximately 14% of SCD cases progress to dementia and about 27% develop MCI over four years.

Objective

This study aims to identify neuropsychological predictors of progression from SCD to MCI, focusing on cognitive domains assessed through neuropsychological tests.

Methods

This retrospective study at Seoul National University Bundang Hospital analyzed a cohort of 107 patients diagnosed with SCD through comprehensive assessment. Patients underwent annual neuropsychological testing, including the Digit Span Test, Boston Naming Test, Rey Complex Figure Test, Seoul Verbal Learning Test, and Stroop Test.

Results

Annually, these patients underwent neuropsychological tests over a 5-year period; 24 progressed to MCI per NIA-AA criteria. Key predictors of MCI progression included age, ischemic heart disease, and scores from the forward digit span, delayed recall, and Boston naming tests. Lower scores in delayed recall and Boston naming tests significantly correlated with a higher risk of MCI (p < 0.001).

Conclusions

These findings suggest a need for targeted management of memory and language functions to monitor disease progression effectively.

Difference in trajectories according to early amyloid accumulation in cognitively unimpaired elderly

BACKGROUND AND PURPOSE

Amyloid β (Aβ), a major biomarker of Alzheimer's disease, leads to tau accumulation, neurodegeneration and cognitive decline. Modelling the trajectory of Aβ accumulation in cognitively unimpaired (CU) individuals is crucial, as treatments targeting Aβ are anticipated. The evolution of Aβ levels was investigated to determine whether it could lead to classification into different groups by studying longitudinal Aβ changes in older CU individuals, and differences between the groups were compared.

METHODS

A total of 297 CU participants were included from the Alzheimer's Disease Neuroimaging Initiative database, and these participants underwent apolipoprotein E (APOE) genotyping, neuropsychological testing, brain magnetic resonance imaging, and an average of 3.03 follow-up 18F-florbetapir positron emission tomography scans. Distinct Aβ trajectory patterns were classified using latent class growth analysis, and longitudinal cognitive performances across these patterns were assessed with a linear mixed effects model.

RESULTS

The optimal model consisted of three classes, with a high entropy value of 0.947. The classes were designated as follows: class 1, non-accumulation group (n  = 197); class 2, late accumulation group (n  = 70); and class 3, early accumulation group (n  = 30). The late accumulation and early accumulation groups had more APOE ε4 carriers than the non-accumulation group. The longitudinal analysis of cognitive performance revealed that the early accumulation group showed the steepest decline (modified Preclinical Alzheimer's Cognitive Composite with digit symbol substitution [mPACCdigit], p < 0.001; modified Preclinical Alzheimer's Cognitive Composite with trails B [mPACCtrailsB], p < 0.001) and the late accumulation group showed a steeper decline (mPACCdigit, p = 0.014; mPACCtrailsB, p = 0.007) compared to the non-accumulation group.

CONCLUSIONS

Our study showed the heterogeneity of Aβ accumulation trajectories in CU older individuals. The prognoses for cognitive decline differ according to the Aβ trajectory patterns.

Effects of a nurse-led staged integral art-based cognitive intervention for older adults on the Alzheimer's disease spectrum: A randomized controlled trial

BACKGROUND

Combined art activities can improve the neural network function within various brain regions involved in emotions, cognition, and behavior, thereby preventing or reversing cognitive decline. However, few studies have systematically examined its effects. Furthermore, the impact of nurse-led art-based cognitive intervention on cognitive and psychological health is unclear.

OBJECTIVE

To evaluate the effects of a nurse-led staged integral art-based cognitive intervention in older adults on the Alzheimer's disease spectrum.

DESIGN

This was a randomized wait-list controlled trial with allocation concealment and blinding of outcome assessors and data analysts. All data were collected between April 2021 and January 2023 and analyzed from January to March 2023.

SETTING

One memory clinic and four medical partnership communities.

PARTICIPANTS

A total of 144 participants with subjective or objective memory decline (aged ≥60 years).

METHODS

Participants were randomized into an intervention group (n = 72) and a wait-list control group (n = 72), in a 1:1 ratio. The intervention group underwent a 16-week, 24-session nurse-led staged integral art-based cognitive intervention program, which was based on neurocognitive function training patterns. The control group underwent the program after the follow-up assessment. General and specific domains of cognitive function and other health-related outcomes were measured at baseline (T0), immediately after the intervention (T1), and at the 6-month follow-up (T2).

RESULTS

Of the 144 participants (mean [SD] age, 71.6 [5.8] years; 50 [34.7 %] males and 94 [65.3 %] females), 130 and 115 completed the questionnaires at T1 and T2, respectively. The average attendance rate in the intervention group was 86.0 %. At T1, the intervention group showed greater improvement than the control group did in general cognitive functions (MoCA, between-group mean difference, 1.4 [95 % CIs, 0.4 to 2.5], p = 0.009). Additionally, the intervention group demonstrated statistically significant improvement compared to the control group in language, memory, quality of life, sleep quality and physical activity level at T1. Statistically significant group differences remained in sleep quality (PSQI, between-group mean difference, -1.3 [95 % CIs, -2.5 to -0.1], p = 0.035) at the 6-month follow-up.

CONCLUSIONS

In this randomized controlled trial of a nurse-led staged integral art-based cognitive intervention program, older adults on the Alzheimer's disease spectrum who participated in the program experienced improved cognition and psychological health.

REGISTRATION

This study was registered with ChiCTR.org (ChiCTR2100044959) on April 3, 2021.

TWEETABLE ABSTRACT

A nurse-led staged integral art-based intervention for older adults on the Alzheimer's disease spectrum experienced improved cognition and psychological health.

Just as expected? Older adults' aging expectations are associated with subjective cognition

OBJECTIVES

This study investigated the relationship between older adults' expectations regarding aging and subjective cognition. Specifically, we examined whether the three domains of aging expectations (physical health, mental health, and cognitive function) were associated with two aspects of subjective cognition: current subjective cognition and subjective cognitive decline (SCD).

METHOD

An online survey was conducted among U.S. adults aged 65-90 (N = 581; Mage=71.4, SD ± 4.81; 51% female). Measures included the 12-item Expectations Regarding Aging scale, the 8-item PROMIS Cognitive Abilities scale (current subjective cognition), and the 12-item Everyday Cognition scale (SCD). We used generalized linear models to examine associations between overall aging expectations and its three domains with current subjective cognition ratings and SCD.

RESULTS

We found that more positive expectations regarding physical health, mental health, and cognitive function in aging were associated with higher ratings of current subjective cognition as well as lower SCD. The magnitude of effects across aging expectations domains were similar for both aspects of subjective cognition.

CONCLUSION

Aging expectations are malleable and influence an individual's perceptions of their cognitive functioning. Modifying older adults' aging expectations could support healthier cognitive aging through increased awareness and accurate assumptions about the aging process.

Connecting genomic and proteomic signatures of amyloid burden in the brain

Background

Alzheimer's disease (AD) has a high heritable component characteristic of complex diseases, yet many of the genetic risk factors remain unknown. We combined genome-wide association studies (GWAS) on amyloid endophenotypes measured in cerebrospinal fluid (CSF) and positron emission tomography (PET) as surrogates of amyloid pathology, which may be helpful to understand the underlying biology of the disease.

Methods

We performed a meta-analysis of GWAS of CSF Aβ42 and PET measures combining six independent cohorts (n=2,076). Due to the opposite effect direction of Aβ phenotypes in CSF and PET measures, only genetic signals in the opposite direction were considered for analysis (n=376,599). Polygenic risk scores (PRS) were calculated and evaluated for AD status and amyloid endophenotypes. We then searched the CSF proteome signature of brain amyloidosis using SOMAscan proteomic data (Ace cohort, n=1,008) and connected it with GWAS results of loci modulating amyloidosis. Finally, we compared our results with a large meta-analysis using publicly available datasets in CSF (n=13,409) and PET (n=13,116). This combined approach enabled the identification of overlapping genes and proteins associated with amyloid burden and the assessment of their biological significance using enrichment analyses.

Results

After filtering the meta-GWAS, we observed genome-wide significance in the rs429358-APOE locus and nine suggestive hits were annotated. We replicated the APOE loci using the large CSF-PET meta-GWAS and identified multiple AD-associated genes as well as the novel GADL1 locus. Additionally, we found a significant association between the AD PRS and amyloid levels, whereas no significant association was found between any Aβ PRS with AD risk. CSF SOMAscan analysis identified 1,387 FDR-significant proteins associated with CSF Aβ42 levels. The overlap among GWAS loci and proteins associated with amyloid burden was very poor (n=35). The enrichment analysis of overlapping hits strongly suggested several signalling pathways connecting amyloidosis with the anchored component of the plasma membrane, synapse physiology and mental disorders that were replicated in the large CSF-PET meta-analysis.

Conclusions

The strategy of combining CSF and PET amyloid endophenotypes GWAS with CSF proteome analyses might be effective for identifying signals associated with the AD pathological process and elucidate causative molecular mechanisms behind the amyloid mobilization in AD.

CSF neurogranin levels as a biomarker in Alzheimer's disease and frontotemporal lobar degeneration: a cross-sectional analysis

BACKGROUND

There is initial evidence suggesting that biomarker neurogranin (Ng) may distinguish Alzheimer's disease (AD) from other neurodegenerative diseases. Therefore, we assessed (a) the discriminant ability of cerebrospinal fluid (CSF) Ng levels to distinguish between AD and frontotemporal lobar degeneration (FTLD) pathology and between different stages within the same disease, (b) the relationship between Ng levels and cognitive performance in both AD and FTLD pathology, and (c) whether CSF Ng levels vary by apolipoprotein E (APOE) polymorphism in the AD continuum.

METHODS

Participants with subjective cognitive decline (SCD) (n = 33), amnestic mild cognitive impairment (aMCI) due to AD (n = 109), AD dementia (n = 67), MCI due to FTLD (n = 25), and FTLD dementia (n = 29) were recruited from the Czech Brain Aging Study. One-way analysis of covariance (ANCOVA) assessed Ng levels in diagnostic subgroups. Linear regressions evaluated the relationship between CSF Ng levels, memory scores, and APOE polymorphism.

RESULTS

Ng levels were higher in aMCI-AD patients compared to MCI-FTLD (F[1, 134] = 15.16, p < .001), and in AD-dementia compared to FTLD-dementia (F[1, 96] = 4.60, p = .029). Additionally, Ng levels were higher in FTLD-dementia patients compared to MCI-FTLD (F[1, 54]= 4.35, p = .034), lower in SCD participants compared to aMCI-AD (F[1, 142] = 10.72, p = .001) and AD-dementia (F[1, 100] = 20.90, p < .001), and did not differ between SCD participants and MCI-FTLD (F[1, 58]= 1.02, p = .491) or FTLD-dementia (F[1, 62]= 2.27, p = .051). The main effect of diagnosis across the diagnostic subgroups on Aβ1-42/Ng ratio was significant too (F[4, 263]=, p < .001). We found a non-significant association between Ng levels and memory scores overall (β=-0.25, p = .154) or in AD diagnostic subgroups, and non-significant differences in this association between overall AD APOE ε4 carriers and non-carriers (β=-0.32, p = .358).

CONCLUSIONS

In this first study to-date to assess MCI and dementia due to AD or FTLD within one study, elevated CSF Ng appears to be an early biomarker of AD-related impairment, but its role as a biomarker appears to diminish after dementia diagnosis, whereby dementia-related underlying processes in AD and FTLD may begin to merge. The Aβ1-42/Ng ratio discriminated AD from FTLD patients better than Ng alone. CSF Ng levels were not related to memory in AD or FTLD, suggesting that Ng may be a marker of the biological signs of disease state rather than cognitive deficits.

The influence of education in predicting conversion from Subjective cognitive decline (SCD) to objective cognitive impairment: A systematic review and meta-analysis

BACKGROUND

Subjective cognitive decline (SCD) is considered a pre-symptomatic stage of dementia characterized by cognitive complaints. The ability of education to reduce the risk of dementia is well known. Our objective is to investigate the influence of education on the risk of progression from SCD to MCI or dementia.

METHODS

Prospective longitudinal studies of adults (≥50 years) with SCD evaluating progression to objective cognitive decline, MCI, or dementia were selected. Pooled estimates (random effects model) and 95 % confidence intervals were calculated, exploring heterogeneity. Standardized education differences, Odds Ratio, or Hazard Ratio between converters and non-converters were estimated.

RESULTS

The systematic review carried out showed that high education, as well as other cognitive reserve proxies, delays cognitive decline. The first meta-analysis showed a significant association of SCD with conversion in both high and low education strata. A second meta-analysis considering education as a continuous variable found that SCD converters showed two years less education than non-converters.

CONCLUSIONS

Our results suggest that education has a delaying effect against cognitive decline progression. The presumed improvement in accurately detecting cognitive decline associated with better metacognitive skills in higher-educated SCD participants does not seem to neutralize the incremental risk of objective cognitive decline associated with lower educational attainment.

Subjective cognitive decline and cognitive change among diverse middle-aged and older Hispanic/Latino adults: Results from the Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA)

INTRODUCTION

The potential utility of subjective cognitive decline (SCD) as an early risk marker of Alzheimer's disease and related dementias is under consideration. We examined associations between SCD and cognitive change among middle-aged and older Hispanic/Latino adults living in the United States.

METHODS

The short-form Everyday Cognition Scale (ECog-12) was assessed to generate global, executive function, and memory-related SCD scores. We used survey generalized regressions to model the change in learning, memory, verbal fluency, executive function, and global cognitive performance over 7 years as a function of SCD (at Visit 2).

RESULTS

The mean age was 56.37 ± 8.10 years at Visit 1 (n = 6225). Higher ECog-12 was associated with greater decline in global cognitive performance (ECog-12 global: B = -0.17, standard error [SE] = 0.02; ECog-12 executive: B = -0.15, SE = 0.02; ECog-12 memory: B = -0.14, SE = 0.02, p's < 0.001).

DISCUSSION

These results support the link between subjective reports of cognitive decline and objectively measured 7-year cognitive decline in community-dwelling, middle-aged, and older Hispanic/Latino adults.

HIGHLIGHTS

We found that nearly two-thirds of diverse middle-aged and older Hispanics/Latinos reported cognitive concerns in a large and representative population study. Self-reported subjective experiences of cognitive decline reflect objective cognitive decline in US Hispanics/Latinos. The relationship is stronger among men compared to women. The relationship between subjective and objective changes to memory are stronger in those with cognitive concerns, and remain even in cognitively healthy individuals.

User Experience of a (Semi-) Automated Cognitive Phone-Based Assessment Within a Memory Clinic Population

OBJECTIVE

We examined the user experience in different modalities (face-to-face, semi-automated phone-based, and fully automated phone-based) of cognitive testing in people with subjective cognitive decline and mild cognitive impairment.

METHOD

A total of 67 participants from the memory clinic of the Maastricht University Medical Center+ participated in the study. The study consisted of cognitive tests in different modalities, namely, face-to-face, semi-automated phone-based guided by a researcher, and fully automated phone-based without the involvement of a researcher. After each assessment, a user experience questionnaire was administered, including questions about, for example, satisfaction, simplicity, and missing personal contact, on a seven-point Likert scale. Non-parametric tests were used to compare user experiences across different modalities.

RESULTS

In all modalities, user experiences were rated above average. The face-to-face ratings were comparable to the ratings of the semi-automated phone-based assessment, except for the satisfaction and recommendation items, which were rated higher for the face-to-face assessment. The face-to-face assessment was preferred above the fully automated phone-based assessment on all items. In general, the semi- and fully automated phone-based assessments were comparable (simplicity, conceivability, quality of sound, visiting the hospital, and missing personal contact), while on all the other items, the semi-automated phone-based assessment was preferred.

CONCLUSIONS

User experience was rated high within all modalities. Simplicity, conceivability, comfortability, and participation scores were comparable in the semi-automated phone-based and face-to-face assessment. Based on these findings and earlier research on validation of the semi-automated phone-based assessment, the semi-automated assessment could be useful for screening for clinical trials, and after more research, in clinical practice.

Impact of multiple infections on risk of incident dementia according to subjective cognitive decline status: a nationwide population-based cohort study

Background

The interrelation between infections, subjective cognitive decline (SCD), and dementia development is recognized, but not fully understood. This study explored the combined effect of specific infections and SCD on the risk of dementia.

Objectives

To assess the influence of Helicobacter pylori, herpes simplex virus, varicella-zoster virus, and human papillomavirus on dementia risk in individuals with varying cognitive statuses, especially focusing on those with and without SCD.

Methods

A cohort of 1,100,540 participants aged 66 years from the Korean National Health Insurance Service was divided into cognitively preserved (CP, n = 825,405) and SCD (n = 275,135) groups. This study analyzed the effects of single, dual, and triple infections on the risk of overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD) using incidence rates and hazard ratios.

Results

The SCD group consistently showed a doubled risk of dementia, particularly AD, regardless of the number of infections. In the initial data, both the presence and number of infections, especially in the CP group, were associated with an increased dementia incidence and risk; however, this correlation disappeared after adjusting for covariates, hinting at a possible protective effect.

Conclusion

Our findings emphasize that, while SCD is a steadfast risk factor for dementia, the role of infections is layered, subject to various influences, and requires more comprehensive exploration to fully understand their impact on dementia development.

Are subjective language complaints in memory clinic patients informative?

To diagnose mild cognitive impairment, it is crucial to understand whether subjective cognitive complaints reflect objective cognitive deficits. This question has mostly been investigated in the memory domain, with mixed results. Our study was one of the first to address it for language. Participants were 55-to-93-year-old memory clinic patients (n = 163). They filled in a questionnaire about subjective language and memory complaints and performed two language tasks (naming-by-definition and sentence comprehension). Greater language complaints were associated with two language measures, thus showing a moderate value in predicting language performance. Greater relative severity of language versus memory complaints was a better predictor, associated with three language performance measures. Surprisingly, greater memory complaints were associated with better naming, probably due to anosognosia in further disease progression or personality-related factors. Our findings highlight the importance of relative complaint severity across domains and, clinically, call for developing self-assessment questionnaires asking specific questions about multiple cognitive functions.

Age-adjusted CSF t-tau and NfL do not improve diagnostic accuracy for prodromal Alzheimer's disease

Cerebrospinal fluid total-tau (t-tau) and neurofilament light chain (NfL) are biomarkers of neurodegeneration and are increased in Alzheimer's disease (AD). In order to adjust for age-related increases in t-tau and NfL, cross-sectional age-adjusted norms were developed based on amyloid negative cognitively normal (CN) adults aged 41-78 years (CN, n = 137). The age-adjusted norms for t-tau and NfL did not improve receiver operating curve based diagnostic accuracies in individuals with mild cognitive impairment (MCI) due to AD (AD-MCI, n = 144). Furthermore, while NfL was correlated with higher age in AD-MCI, no significant correlation was found for t-tau. The cox proportional hazard models, applied in 429 participants with baseline t-tau and NfL, showed higher hazard ratio of progression to MCI or dementia without age-adjustments (HR = 3.39 for t-tau and HR = 3.17 for NfL), as compared to using our norms (HR = 2.29 for t-tau and HR = 1.89 for NfL). Our results indicate that utilizing normative reference data could obscure significant age-related increases in these markers associated with neurodegeneration and AD leading to a potential loss of overall diagnostic accuracy.

Association between elevated blood-brain barrier permeability and the risk of progressive cognitive decline: A longitudinal study

BACKGROUND

The breakdown of the blood-brain barrier (BBB) is intricately linked to the onset and advancement of cognitive impairment and dementia. This investigation explores the correlation between blood-brain barrier permeability, assessed through the cerebrospinal fluid/serum albumin ratio (QAlb), in a clinical cohort and the evolution of cognitive decline.

METHODS

This prospective observational cohort study included 295 participants. Cognitive decline progression was characterized by an escalation in the overall deterioration scale and/or clinical dementia rating scores. The investigation delves into the correlation between blood-brain barrier permeability and the advancement of cognitive impairment among patients.

RESULTS

The APOE 4 allele and diabetes mellitus among individuals exhibited increased BBB permeability (P < 0.05). Moreover, AD patients exhibited the highest QAlb levels, signifying elevated BBB permeability compared to individuals with MCI and SCD (P < 0.05). After mean 17 months following up, 117 patients (51.31 %) were identified as experiencing cognitive decline progression, and we found that only AD diagnosis, CDR, and QAlb (All P < 0.05) were significant predictors of cognitive decline progression.

CONCLUSION

Our study emphasizes the clinical relevance of QAlb in detecting individuals with an elevated risk of cognitive decline. It suggests that heightened BBB permeability could contribute to clinical deterioration and serves as a plausible therapeutic target.

Accurate identification of individuals with subjective cognitive decline using 3D regional fractal dimensions on structural magnetic resonance imaging

BACKGROUND AND OBJECTIVE

Accurate identification of individuals with subjective cognitive decline (SCD) is crucial for early intervention and prevention of neurodegenerative diseases. Fractal dimensionality (FD) has emerged as a robust and replicable measure, surpassing traditional geometric metrics, in characterizing the intricate fractal geometrical properties of brain structure. Nevertheless, the effectiveness of FD in identifying individuals with SCD remains largely unclear. A 3D regional FD method can be suggested to characterize and quantify the spatial complexity of the precise gray matter, providing insights into cognitive aging and aiding in the automated identification of individuals with SCD.

METHODS

This study introduces a novel integer ratio based 3D box-counting fractal analysis (IRBCFA) to quantify regional fractal dimensions (FDs) in structural magnetic resonance imaging (MRI) data. The innovative method overcomes limitations of conventional box-counting techniques by accommodating arbitrary box sizes, thereby enhancing the precision of FD estimation in small, yet neurologically significant, brain regions.

RESULTS

The application of IRBCFA to two publicly available datasets, OASIS-3 and ADNI, consisting of 520 and 180 subjects, respectively. The method identified discriminative regions of interest (ROIs) predominantly within the limbic system, fronto-parietal region, occipito-temporal region, and basal ganglia-thalamus region. These ROIs exhibited significant correlations with cognitive functions, including executive functioning, memory, social cognition, and sensory perception, suggesting their potential as neuroimaging markers for SCD. The identification model trained on these ROIs demonstrated exceptional performance achieving over 93 % accuracy on the discovery dataset and exceeding 87 % on the independent testing dataset. Furthermore, an exchange experiment between datasets revealed a substantial overlap in discriminative ROIs, highlighting the robustness of our method across diverse populations.

CONCLUSION

Our findings indicate that IRBCFA can serve as a valuable tool for quantifying the spatial complexity of gray matter, providing insights into cognitive aging and aiding in the automated identification of individuals with SCD. The demonstrated generalizability and robustness of this method position it as a promising tool for neurodegenerative disease research and offer potential for clinical applications.

Confronting Alzheimer's Disease Risk in Women: A Feasibility Study of Memory Screening as Part of the Annual Gynecological Well-Woman Visit

Objective: Routine health care visits offer the opportunity to screen older adults for symptoms of Alzheimer's disease (AD). Many women see their gynecologist as their primary health care provider. Given this unique relationship, the Women's Preventive Services Initiative and the American College of Obstetrics and Gynecology advocate for integrated care of women at all ages. It is well-established that women are at increased risk for AD, and memory screening of older women should be paramount in this effort. Research is needed to determine the feasibility and value of memory screening among older women at the well-woman visit. Materials and Methods: Women aged 60 and above completed a 5-item subjective memory screener at their well-woman visit at the Columbia University Integrated Women's Health Program. Women who endorsed any item were considered to have a positive screen and were given the option to pursue clinical evaluation. Rates of positive screens, item endorsement, and referral preferences were examined. Results: Of the 530 women approached, 521 agreed to complete the screener. Of those, 17.5% (n = 91) were classified as positive. The most frequently endorsed item was difficulty with memory or thinking compared with others the same age. Among women with positive screens, 57.5% were interested in pursuing clinical referrals to a memory specialist. Conclusion: Results support the feasibility and potential value of including subjective memory screening as part of a comprehensive well-woman program. Early identification of memory loss will enable investigation into the cause of memory symptoms and longitudinal monitoring of cognitive change.

Subjective memory complaints in young people: the role of resilience

OBJECTIVE

Little is known about the origin and associated factors of subjective memory complaints (SMCs) in the young population, although they might be closely related to the psychophysiological states produced by stress exposure, such as anxiety and depression. In this regard, resilience has been related to a reduction in these negative states, as well as to more adaptive hypothalamic-pituitary-adrenal (HPA) axis functioning. We aimed to investigate the importance of depression, anxiety, and HPA axis activity in SMCs in the young population. We also analysed the relationship between resilience and SMCs through the mediation of depression, anxiety, and the cortisol awakening response (CAR).

DESIGN

To do so, we measured SMCs, depression and anxiety states, resilience, and the CAR in 77 healthy young people.

RESULTS

Both depression and anxiety were associated with SMCs. In addition, greater resilience was related to fewer SMCs through depression and anxiety. However, the CAR was not related to SMCs, and it did not mediate the relationship between resilience and SMCs.

CONCLUSION

These results suggest that negative affective states have greater importance in SMCs than HPA functioning in this age group, and they also highlight the importance of resilience in the psychological adjustment to stressful situations.

Subjective Cognitive Dysfunction in Chronic Illness: A Systematic Review and Meta-Synthesis

BACKGROUND

Qualitative studies have examined the experiences of subjective cognitive dysfunction in specific populations or specific disease stages, but there has not yet been a systematic synthesis and evaluation of findings related to perceptions of subjective cognitive dysfunction in nondementia-related chronic illnesses.

OBJECTIVE

The aim of this study was 2-fold: (1) to undertake a systematic review of experiences of subjective cognitive dysfunction in people with nondementia-related chronic disease and (2) to develop an explanatory framework to describe the experiences of living with subjective cognitive dysfunction.

METHODS

Four databases were systematically searched for studies on subjective cognitive dysfunction up to June 2023. Qualitative synthesis was conducted on the final sample (N = 25) using Sandelowski's adaptation of Nobilt and Hare's reciprocal transactional analysis method. Critical appraisal was completed using the Critical Appraisal Skills Programme checklist.

RESULTS

Through constant comparison of key concepts, findings were organized within 4 interrelated themes that informed a conceptual explanatory model of adapting to living with subjective cognitive dysfunction: (1) symptoms, (2) health care, (3) perceptions of self, and (4) relationships. Participants highlighted how subjective cognitive dysfunction affected interactions in health care settings and involved other symptoms that in turn complicated meaning, self-enhancement, and mastery.

CONCLUSIONS

Our model of the process of adapting provides a new way to conceptualize cognitive dysfunction in chronic illness and suggests opportunities for health care professionals to support patients and their families. The results highlight the need for more research to better understand the role of subjective cognitive dysfunction in nondementia-related chronic illnesses.The review protocol was registered in PROSPERO (CRD42021231410).

Volumetric and functional connectivity changes of the thalamic nuclei in different stages of Alzheimer's disease

OBJECTIVE

Memory processes known to be impaired in Alzheimer's disease (AD) are maintained by a large-scale neurocognitive network with subcortical components, including the thalamus. Therefore, we aimed to examine the volumetric and functional changes of the thalamic nuclei at different scales across AD stages.

METHODS

MRI data of patients diagnosed with 20 AD dementia (ADD), 30 amnestic mild cognitive impairment (MCI), and 30 subjective cognitive impairment (SCI) were used. Volumetric and functional connectivity analyzes were performed by dividing the thalamus into anterior, medial, posterior, lateral and intralaminar nucleus groups and their specific subnuclei.

RESULTS

In the course of AD, the volume of the medial group nuclei, especially the mediodorsal medial magnocellular (MDm) nucleus, decreases. Medial group nuclei and MDm functional connectivity with frontal areas were decreased both in ADD and MCI compared to SCI group, while both of them increased their functional connectivity with visual areas in the ADD group compared to the MCI group.

CONCLUSIONS

Our study suggests that the medial group of the thalamus, and specifically the MDm, may be affected in AD.

SIGNIFICANCE

Specific thalamic nuclei may be a critical anatomical region for investigating structural and functional changes in AD.

EEG frequency bands in subjective cognitive decline: A systematic review of resting state studies

As the older population continues to expand, there is a growing prevalence of individuals who experience subjective cognitive decline (SCD), characterized by self-reported failures in cognitive function and an increased risk of cognitive impairment. Recognizing that preventive interventions are typically more effective in preclinical stages, current research endeavors to focus on identifying early biological markers of SCD using resting-state electroencephalogram (rsEEG) methods. To do so, a systematic literature review covering the past 20 years was conducted following PRISMA guidelines, in order to consolidate findings on rsEEG frequency bands in individuals with SCD. Pubmed and Web of Science databases were searched for rsEEG studies of people with SCD. Quality assessments were completed using a modified Newcastle-Ottawa scale. A total of 564 articles published from December 2003 to December 2023 were reviewed, and significant aspects of these papers were analyzed to provide a general overview of the research on this technique. After removing unrelated articles, nine articles were selected for the present study. The review emphasizes patterns in frequency band activity, revealing that individuals classified as SCD exhibited increased theta power than healthy controls, but decreased than MCI. However, findings for the alpha, delta, and beta bands were inconsistent, demonstrating variability across studies and highlighting the need for further research. Although the rsEEG of frequency bands emerges as a promising early biomarker, there is a noteworthy need to establish uniform standards and consistent measurement approaches in order to ensure the reliability and comparability of the results obtained in the research.

Machine Learning-Based Perivascular Space Volumetry in Alzheimer Disease

OBJECTIVES

Impaired perivascular clearance has been suggested as a contributing factor to the pathogenesis of Alzheimer disease (AD). However, it remains unresolved when the anatomy of the perivascular space (PVS) is altered during AD progression. Therefore, this study investigates the association between PVS volume and AD progression in cognitively unimpaired (CU) individuals, both with and without subjective cognitive decline (SCD), and in those clinically diagnosed with mild cognitive impairment (MCI) or mild AD.

MATERIALS AND METHODS

A convolutional neural network was trained using manually corrected, filter-based segmentations (n = 1000) to automatically segment the PVS in the centrum semiovale from interpolated, coronal T2-weighted magnetic resonance imaging scans (n = 894). These scans were sourced from the national German Center for Neurodegenerative Diseases Longitudinal Cognitive Impairment and Dementia Study. Convolutional neural network-based segmentations and those performed by a human rater were compared in terms of segmentation volume, identified PVS clusters, as well as Dice score. The comparison revealed good segmentation quality (Pearson correlation coefficient r = 0.70 with P < 0.0001 for PVS volume, detection rate in cluster analysis = 84.3%, and Dice score = 59.0%). Subsequent multivariate linear regression analysis, adjusted for participants' age, was performed to correlate PVS volume with clinical diagnoses, disease progression, cerebrospinal fluid biomarkers, lifestyle factors, and cognitive function. Cognitive function was assessed using the Mini-Mental State Examination, the Comprehensive Neuropsychological Test Battery, and the Cognitive Subscale of the 13-Item Alzheimer's Disease Assessment Scale.

RESULTS

Multivariate analysis, adjusted for age, revealed that participants with AD and MCI, but not those with SCD, had significantly higher PVS volumes compared with CU participants without SCD ( P = 0.001 for each group). Furthermore, CU participants who developed incident MCI within 4.5 years after the baseline assessment showed significantly higher PVS volumes at baseline compared with those who did not progress to MCI ( P = 0.03). Cognitive function was negatively correlated with PVS volume across all participant groups ( P ≤ 0.005 for each). No significant correlation was found between PVS volume and any of the following parameters: cerebrospinal fluid biomarkers, sleep quality, body mass index, nicotine consumption, or alcohol abuse.

CONCLUSIONS

The very early changes of PVS volume may suggest that alterations in PVS function are involved in the pathophysiology of AD. Overall, the volumetric assessment of centrum semiovale PVS represents a very early imaging biomarker for AD.

Does personality affect the cognitive decline in aging? A systematic review

Cognitive decline is a natural consequence of aging, but several genetic, environmental, and psychological factors can influence its trajectories. Among the most enduring factors, the Big Five personality traits - defined as relatively stable tendencies to think, behave, and react to the environment - can influence both directly (e.g., by physiological correlates) and indirectly (e.g., healthy or risky behaviors) the risk of developing dementia and mild cognitive impairment (MCI) - a preclinical form of cognitive decline. Despite the great amount of studies focusing on the relationship between personality and cognitive decline, an updated systematic synthesis of the results including a broader range of study designs is still lacking. This systematic review aims to summarize the findings of studies investigating: (i) differences in personality traits between groups of healthy individuals and those with MCI, (ii) the impact of personality traits on the risk for both MCI and dementia, and (iii) changes in personality traits among individuals progressing from normal cognition to MCI. Neuroticism emerged as a significant risk factor for MCI and dementia; Conscientiousness and Openness appear to offer protection against dementia and moderate cognitive decline. Overall, these findings suggest a pivotal role of personality structure in shaping cognitive outcomes on the long run.

Energy-adjusted dietary inflammatory index and cognitive function in Chinese older adults: a population-based cross-sectional study

Diet can regulate systemic inflammation, which may play an important role in the development and progression of cognitive impairment and dementia. To explore the relationship between the dietary inflammatory potential and cognitive ability. A total of 2307 adults aged 60 years or older were recruited from the Fujian Provincial Hospital (Fujian, China). Dietary inflammatory properties were analyzed using the energy-adjusted dietary inflammatory index (E-DII). The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to assess cognitive function. Logistic regression and restricted cubic spline (RCS) were fit to assess the associations between variables. The MCI subjects with the highest E-DII scores had a higher risk of AD compared to subjects with the lowest E-DII scores (OR = 1.98, 95%CI = 1.49-2.64, P for trend < 0.001). Subjects with the highest E-DII levels were at increased risk of cognitive impairment compared to those with the lowest E-DII levels (OR = 1.56, 95%CI = 1.25-1.93, P for trend < 0.001). The link between E-DII and cognitive impairment was significant in a nonlinear dose response analysis (P for nonlinear = 0.001). Higher E-DII scores were associated with an increased risk of developing AD or cognitive impairment. These findings may contribute to the effective prevention of cognitive impairment by constructing a multidisciplinary synergistic prevention strategy and controlling dietary inflammation levels.

Depressive symptoms-Not a predictor for five-year mortality in patients with subjective cognitive decline, non-amnestic and amnestic mild cognitive impairment

The main aim of the present study is to evaluate the influence of depressive symptoms on mortality in patients with SCD (subjective cognitive decline), naMCI (non-amnestic mild cognitive impairment), and aMCI (amnestic mild cognitive impairment). Additional factors (age, sex, years of school attendance, and neuropsychological performance) were considered to determine the impact on survival probability. A monocentric retrospective data analysis based on adjusted patient protocols (n = 1221) from the observation period 1998-2021, using the Cox Proportional Hazards model, assessed whether depressivity had an explanatory value for survival, considering SCD as the reference level in relation to naMCI and aMCI. Covariates were included blockwise. Cox regression revealed that depressiveness (Beck Depression Inventory, Geriatric Depression Scale) did not make a significant contribution as a risk factor for mortality in all five model blocks, BDI-II with HR 0.997 [0.978; 1.02] and GDS-15 with HR 1.03 [0.98; 1.08]. Increasing age with HR 1.09 [1.07; 1.11] and male sex with HR (inverted) 1.53 [1.17; 2.00] appeared as risk factors for increased mortality across all five model blocks. aMCI (vs. SCD) with HR 1.91 [1.33; 2.76] showed a significant explanatory value only up to the fourth model block. By adding the six dimensions of the Neuropsychological Test Battery Vienna in the fifth model block, the domains attention and perceptual speed with HR 1.34 [1.18; 1.53], and executive functions with HR 1.24 [1.11; 1.39], showed substantial explanatory values for survival. Accordingly, no tendency can be attributed to depressiveness as a risk factor on the probability of survival, whereas the influence of certain cognitive dimensions, especially attention and perceptual speed, and executive functions, can be seen as protective for survival.

Alteration in temporal-cerebellar effective connectivity can effectively distinguish stable and progressive mild cognitive impairment

Background

Stable mild cognitive impairment (sMCI) and progressive mild cognitive impairment (pMCI) represent two distinct subtypes of mild cognitive impairment (MCI). Early and effective diagnosis and accurate differentiation between sMCI and pMCI are crucial for administering targeted early intervention and preventing cognitive decline. This study investigated the intrinsic dysconnectivity patterns in sMCI and pMCI based on degree centrality (DC) and effective connectivity (EC) analyses, with the goal of uncovering shared and distinct neuroimaging mechanisms between subtypes.

Methods

Resting-state functional magnetic resonance imaging combined with DC analysis was used to explore the functional connectivity density in 42 patients with sMCI, 31 patients with pMCI, and 82 healthy control (HC) participants. Granger causality analysis was used to assess changes in EC based on the significant clusters found in DC. Furthermore, correlation analysis was conducted to examine the associations between altered DC/EC values and cognitive function. Receiver operating characteristic curve analysis was performed to determine the accuracy of abnormal DC and EC values in distinguishing sMCI from pMCI.

Results

Compared with the HC group, both pMCI and sMCI groups exhibited increased DC in the left inferior temporal gyrus (ITG), left posterior cerebellum lobe (CPL), and right cerebellum anterior lobe (CAL), along with decreased DC in the left medial frontal gyrus. Moreover, the sMCI group displayed reduced EC from the right CAL to bilateral CPL, left superior temporal gyrus, and bilateral caudate compared with HC. pMCI demonstrated elevated EC from the right CAL to left ITG, which was linked to episodic memory and executive function. Notably, the EC from the right CAL to the right ITG effectively distinguished sMCI from pMCI, with sensitivity, specificity, and accuracy of 0.5806, 0.9512, and 0.828, respectively.

Conclusion

This study uncovered shared and distinct alterations in DC and EC between sMCI and pMCI, highlighting their involvement in cognitive function. Of particular significance are the unidirectional EC disruptions from the cerebellum to the temporal lobe, which serve as a discriminating factor between sMCI and pMCI and provide a new perspective for understanding the temporal-cerebellum. These findings offer novel insights into the neural circuit mechanisms involving the temporal-cerebellum connection in MCI.

Prevalence, risk factors, and impact of anxiety in early Alzheimer disease: a retrospective study of an autopsy-confirmed cohort

Anxiety is a neuropsychiatric symptom (NPS) of Alzheimer disease (AD) patients which has been studied primarily in prospective and retrospective studies of clinically diagnosed AD. However, this can be confounded by other primary etiologies. Moreover, anxiety has not been comprehensively studied in autopsy-confirmed AD cases across subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia stages. We conducted a retrospective longitudinal analysis of 212 participants with autopsy-confirmed AD, followed from 1986-2013 at the NYU Alzheimer's Disease Research Center with staging via the Global Deterioration Scale and NPS assessed via BEHAVE-AD. We found that anxiety varied uniquely with stage and was the most common NPS in SCD and MCI (35-40% prevalence). ApoE4 carriage associated with a higher rate of anxiety only at mild dementia. Anxiety in SCD associated with cerebral amyloid angiopathy and arteriosclerosis on brain autopsy, but there were no such associations with concomitant neuropathology at MCI and mild dementia. Anxiety associated with increased progression rate (∼2.5-fold) from SCD to MCI/dementia stages, but not from MCI to dementia. These results suggest an important relationship between anxiety and AD, especially at the preclinical stage. This warrants further study of anxiety as a possible modifiable factor of disease experience and course.

Serum proteomics reveal APOE-ε4-dependent and APOE-ε4-independent protein signatures in Alzheimer's disease

A deeper understanding of the molecular processes underlying late-onset Alzheimer's disease (LOAD) could aid in biomarker and drug target discovery. Using high-throughput serum proteomics in the prospective population-based Age, Gene/Environment Susceptibility-Reykjavik Study (AGES) cohort of 5,127 older Icelandic adults (mean age, 76.6 ± 5.6 years), we identified 303 proteins associated with incident LOAD over a median follow-up of 12.8 years. Over 40% of these proteins were associated with LOAD independently of APOE-ε4 carrier status, were implicated in neuronal processes and overlapped with LOAD protein signatures in brain and cerebrospinal fluid. We identified 17 proteins whose associations with LOAD were strongly dependent on APOE-ε4 carrier status, with mostly consistent associations in cerebrospinal fluid. Remarkably, four of these proteins (TBCA, ARL2, S100A13 and IRF6) were downregulated by APOE-ε4 yet upregulated due to LOAD, a finding replicated in external cohorts and possibly reflecting a response to disease onset. These findings highlight dysregulated pathways at the preclinical stages of LOAD, including those both independent of and dependent on APOE-ε4 status.

Non-Linear Association of Dietary Polyamines with the Risk of Incident Dementia: Results from Population-Based Cohort of the UK Biobank

Natural polyamines, including spermidine (SPD), spermine (SPM) and putrescine (PUT), are evolutionarily conserved endogenous molecules crucially involved in central cellular processes. Their physiological importance may extend to the maintenance of cognitive function during aging. However, limited population-based epidemiological studies have explored the link between dietary polyamines and dementia risk. This study was a prospective analysis of 77,092 UK Biobank participants aged ≥ 60 years without dementia at baseline. We used Cox proportional hazard regression models to explore the associations between dietary polyamines and the risk of dementia, and restricted cubic splines to test the non-linear relationships. During a median follow-up of 12 years, 1087 incidents of all-cause dementia cases occurred, including 450 Alzheimer's disease (AD) cases and 206 vascular dementia (VD) cases. The fully adjusted hazard ratios (HRs) for the upper fourth quintile of dietary SPD, in comparison with the lowest quintile of intake, were 0.68 (95% confidence interval [95% CI]: 0.66-0.83) for the risk of all-cause dementia, 0.62 (95% CI: 0.45-0.85) for AD and 0.56 (95% CI: 0.36-0.88) for VD, respectively. A 26% reduction in dementia risk [HR: 0.74, (95% CI: 0.61-0.89)] and a 47% reduction in AD [HR: 0.53, (95%CI: 0.39-0.72)] were observed comparing the third with the lowest quintiles of dietary SPM. Dietary PUT was only associated with a reduced risk of all-cause dementia in the fourth quintile [HR (95% CI): 0.82 (0.68-0.99)]. Reduced risk was not found to be significant across all quintiles. There were 'U'-shaped relationships found between dietary polyamines and all-cause dementia, AD and VD. Stratification by genetic predisposition showed no significant effect modification. Optimal intake of polyamines was linked to a decreased risk of dementia, with no modification by genetic risk. This potentially suggests cognitive benefits of dietary natural polyamines in humans.

Comparison of subjective cognitive decline and polygenic risk score in the prediction of all-cause dementia, Alzheimer's disease and vascular dementia

BACKGROUND

Polygenic risk scores (PRS) and subjective cognitive decline (SCD) are associated with the risk of developing dementia. It remains to examine whether they can improve the established cardiovascular risk factors aging and dementia (CAIDE) model and how their predictive abilities compare.

METHODS

The CAIDE model was applied to a sub-sample of a large, population-based cohort study (n = 5,360; aged 50-75) and evaluated for the outcomes of all-cause dementia, Alzheimer's disease (AD) and vascular dementia (VD) by calculating Akaike's information criterion (AIC) and the area under the curve (AUC). The improvement of the CAIDE model by PRS and SCD was further examined using the net reclassification improvement (NRI) method and integrated discrimination improvement (IDI).

RESULTS

During 17 years of follow-up, 410 participants were diagnosed with dementia, including 139 AD and 152 VD diagnoses. Overall, the CAIDE model showed high discriminative ability for all outcomes, reaching AUCs of 0.785, 0.793, and 0.789 for all-cause dementia, AD, and VD, respectively. Adding information on SCD significantly increased NRI for all-cause dementia (4.4%, p = 0.04) and VD (7.7%, p = 0.01). In contrast, prediction models for AD further improved when PRS was added to the model (NRI, 8.4%, p = 0.03). When APOE ε4 carrier status was included (CAIDE Model 2), AUCs increased, but PRS and SCD did not further improve the prediction.

CONCLUSIONS

Unlike PRS, information on SCD can be assessed more efficiently, and thus, the model including SCD can be more easily transferred to the clinical setting. Nevertheless, the two variables seem negligible if APOE ε4 carrier status is available.

Differential neuropsychiatric associations of plasma biomarkers in older adults with major depression and subjective cognitive decline

Older adults with major depressive disorder (MDD) or early cognitive decline during the subjective cognitive decline (SCD) stage may exhibit neuropsychiatric symptoms such as anxiety, depression, and subtle cognitive impairment. The clinicopathological features and biological mechanisms of MDD differ from those of SCD among older adults; these conditions thus require different treatment strategies. This study enrolled 82 participants above 50 years old with normal cognitive levels from the communities to examine biomarker-behavior correlations between MDD (n = 23) and SCD (n = 23) relative to a normal control (NC) group (n = 36). Multidomain assessments were performed for all participants, including immunomagnetic reduction tests to detect plasma beta-amyloid (Aβ), total tau (Tau), phosphorylated tau-181 (p-Tau181), neurofilament light chain, and glial fibrillary acidic protein (GFAP). This study observed that depressive symptoms in MDD were associated with amyloid pathology (plasma Aβ40 vs. HADS-D: R = 0.45, p = 0.031; Aβ42/Aβ40 vs. HADS-D: R = -0.47, p = 0.024), which was not observed in the NC (group difference p < 0.05). Moreover, cognitive decline in MDD was distinguished by a mixed neurodegenerative process involving amyloid (plasma Aβ42 vs. facial memory test: R = 0.48, p = 0.025), tau (Tau/Aβ42 vs. digit symbol substitution test (DSST): R = -0.53, p = 0.01), and astrocytic injury (plasma GFAP vs. Montreal cognitive assessment score: R = -0.44, p = 0.038; plasma GFAP vs. DSST: R = -0.52, p = 0.014), findings that did not apply to the NC (group difference p < 0.05). Moreover, this study revealed different biomarker-behavior correlations between individuals with SCD and the NC. Compared with the NC, cognitive decline in the SCD group might be unrelated to amyloid pathology and instead might be early manifestations of tau pathology. This study underscores the difference in clinicopathological features between MDD and SCD among older adults, which differ from those of the NC. These findings enhance our understanding of the mechanisms underlying MDD and SCD in older individuals.

Altered functional connectivity of primary olfactory cortex-hippocampus-frontal cortex in subjective cognitive decline during odor stimulation

Subjective cognitive decline (SCD) is a high-risk population in the preclinical stage of Alzheimer's disease (AD), and olfactory dysfunction is a risk factor for dementia progression. The present study aimed to explore the patterns of functional connectivity (FC) changes in the olfactory neural circuits during olfactory stimulation in SCD subjects. A total of 56 SCD subjects and 56 normal controls (NCs) were included. All subjects were assessed with a cognitive scale, an olfactory behavior test, and olfactory task-based functional magnetic resonance imaging scanning. The FC differences in olfactory neural circuits between the two groups were analyzed by the generalized psychophysiological interaction. Additionally, we calculated and compared the activation of brain regions within the olfactory neural circuits during odor stimulation, the volumetric differences in brain regions showing FC differences between groups, and the correlations between neuroimaging indicators and olfactory behavioral and cognitive scale scores. During odor stimulation, the FC between the bilateral primary olfactory cortex (bPOC) and the right hippocampus in the SCD group was significantly reduced; while the FC between the right hippocampus and the right frontal cortex was significantly increased in the SCD group. The bPOC of all subjects showed significant activation, but no significant difference in activation between groups was found. No significant differences were observed in the volume of the brain regions within the olfactory neural circuits or in olfactory behavior between groups. The volume of the bPOC and right frontal cortex was significantly positively correlated with olfactory identification, and the volume of the right frontal cortex and right hippocampus was significantly correlated with cognitive functions. Furthermore, a significant correlation between the activation of bPOC and the olfactory threshold was found in the whole cohort. These results suggested that while the structure of the olfactory neural circuits and olfactory behavior in SCD subjects remained stable, there were significant changes observed in the FC of the olfactory neural circuits (specifically, the POC-hippocampus-frontal cortex neural circuits) during odor stimulation. These findings highlight the potential of FC alterations as sensitive imaging markers for identifying high-risk individuals in the early stage of AD.

Impact of repetitive negative thinking on subjective cognitive decline: insights into cognition and brain structure

Introduction

Individuals with subjective cognitive decline (SCD) express concern about self-perceived cognitive decline despite no objective impairment and are at higher risk of developing Alzheimer's disease. Despite documented links between SCD and repetitive negative thinking (RNT), the specific impact of RNT on brain integrity and cognition in exacerbating the SCD condition remains unclear. We aimed to investigate the influence of RNT on global cognition and brain integrity, and their interrelationships among healthy middle-aged and older adults experiencing SCD.

Methods

Out of 616 individuals with neuroimaging and neuropsychological data available, 89 (mean age = 56.18 years; 68.54% females) met SCD criteria. Eighty-nine non-SCD individuals matched by age, sex, and education were also selected and represented the control group (mean age = 56.09 years; 68.54% females). Global cognition was measured using the preclinical Alzheimer's cognitive composite (PACC5), which includes dementia screening, episodic memory, processing speed, and category fluency tests. RNT was calculated through three questionnaires assessing intrusive thoughts, persistent worry, and rumination. We generated cortical thickness (CTh) maps and quantified the volume of white matter lesions (WML) in the whole brain, as grey and white matter integrity measures, respectively.

Results

SCD individuals exhibited higher RNT scores, and thinner right temporal cortex compared to controls. No differences were observed in PACC5 and WML burden between groups. Only the SCD group demonstrated positive associations in the CTh-PACC5, CTh-RNT, and WML-RNT relationships.

Discussion

In this cross-sectional study, RNT was exclusively associated with brain integrity in SCD. Even though our findings align with the broader importance of investigating treatable psychological factors in SCD, further research may reveal a modulatory effect of RNT on the relationship between cognition and brain integrity in SCD.

Brain amyloid load, subjective memory complaints, and cognitive trajectories in older individuals at risk for dementia

BACKGROUND AND PURPOSE

This study evaluated associations of brain amyloid with 2-year objective and subjective cognitive measures in a trial-ready older general population at risk for dementia.

METHODS

Forty-eight participants in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability underwent 11C-Pittsburgh compound B (PiB) positron emission tomography (PET) scans and assessment of cognition (modified Neuropsychological Test Battery [NTB]) and subjective memory complaints (Prospective and Retrospective Memory Questionnaire).

RESULTS

Mean age was 71.4 ± 5.06 years, and 20 participants (42%) had positive baseline PiB-PET scans. Amyloid positivity was associated with lower NTB executive function at baseline and less favorable 2-year NTB total score and memory trajectories, but not with other objective or subjective cognitive measures. Overall, there was little cognitive decline during 2 years.

CONCLUSIONS

Amyloid accumulation may affect objective but not necessarily subjective cognition from a very early at-risk stage, although substantial decline likely requires >2 years to occur.

Retina as a potential biomarker for the early stage of Alzheimer's disease spectrum

OBJECTIVE

To characterize the retinal microvasculature and structure in subjective cognitive decline (SCD) and identify the potential biomarker for the early stage of the Alzheimer's disease (AD) spectrum.

METHODS

In this study, 35 patients with SCD, 36 with cognitive impairment, and 29 with normal cognition (NC) were enrolled. Optical coherence tomography angiography was employed to assess retinal vascular density, fovea avascular zone area, and retinal thickness. The parameters reflecting retinal perfusion and structure were compared among the three groups. In addition, the association between retinal parameters, cerebral blood flow (CBF), and peripheral blood biomarkers in the SCD stage was analyzed.

RESULTS

The superficial vascular complex (SVC) vascular density in the macula and retinal nerve fiber layer thickness in the peripapillary were significantly reduced in individuals with SCD compared to NC. Furthermore, there was a positive correlation between macular ganglion cell complex thickness and CBF in SCD.

INTERPRETATION

The retinal microvasculature and structure exhibit alterations in individuals with SCD. Macular ganglion cell complex thickness demonstrates correlations with cerebral perfusion. The retina holds potential as a novel biomarker for early detection of AD.