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

Subjective cognitive decline and objective cognitive performance in older adults: A systematic review of longitudinal and cross-sectional studies

Older adults with subjective cognitive decline (SCD) have a higher risk of developing future cognitive decline than those without SCD. However, the association between SCD and objective cognitive performance remains unclear. This PRISMA 2020-compliant systematic review aims to provide a qualitative assessment of the longitudinal and cross-sectional relationship between SCD and objective cognitive performance in different cognitive domains, in neuropsychologically healthy, community-dwelling older adults (average age of 55 or older). To identify pertinent studies, a comprehensive search was conducted from seven databases. The National Heart, Lung and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was used to assess the quality of included studies. Inclusion criteria were met by 167 studies, which were full-text and published between 1 January 1982 and 16 May 2023 (inclusive) in the languages of English, French, or Spanish and presenting data on objective cognitive performance in older adults with SCD. Overall, we found that SCD was associated with poorer objective cognitive performance on measures of global cognition and memory longitudinally compared to non-SCD status, but this association was inconsistent in cross-sectional studies. This association became stronger with the use of continuous measures of SCD as opposed to dichotomous measures. Additionally, results highlight the known lack of consistency in SCD assessment among studies and comparatively small number of longitudinal studies in SCD research.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Investigating the overlapping associations of prior concussion, default mode connectivity, and executive function-based symptoms

Growing evidence suggests that younger athletes with greater concussion history are more likely to endorse greater subjective cognitive (e.g., executive function) symptoms, but not perform worse on objective cognitive testing. We sought to identify biological correlates of elevated cognitive symptoms in 100 healthy, collegiate-aged athletes with varying degrees of concussion history. Associations between concussion history with subjectively-rated executive function were assessed with generalized linear models. Using resting state fMRI, we examined associations between concussion history and between-and within-network connectivity across three networks integral to executive function; default mode network (DMN), frontoparietal network (FPN), and ventral attention network (VAN). Relationships of between-and within-network connectivity with subjective executive function were assessed. Although the large majority of participants did not report clinically relevant levels of executive difficulties, there was a significant association between concussion history and higher behavioral regulation-related symptoms; B = .04[.01, .07], p = .011. A significant elevation in total within-network connectivity was observed among those with a greater concussion history, B = .02[.002, .03], p = .028, which was primarily driven by a positive association between concussion history and within DMN connectivity, B = .02[.004, .04], p = .014. Higher behavioral regulation-related symptoms were associated with greater total within-network connectivity, B = 0.57[0.18, 0.96], p = .005, and increased within-network connectivity for the DMN, B = .49[.12, .86], p = .010). The current study identified a distinct biological correlate, increased within-DMN connectivity, which was associated with both a greater history of concussion and greater behavioral regulation symptoms. Future studies are required to determine the degree to which these changes associated with concussion history may evolve toward objective cognitive decline over the lifespan.

Late-life depression, subjective cognitive decline, and their additive risk in incidence of dementia: A nationwide longitudinal study

OBJECTIVE

Late-life depression and subjective cognitive decline (SCD) are significant risk factors for dementia. However, studies with a large sample size are needed to clarify their independent and combined risks for subsequent dementia.

METHODS

This nationwide population-based cohort study included all individuals aged 66 years who participated in the National Screening Program between 2009 and 2013 (N = 939,099). Subjects were followed from the day they underwent screening to the diagnosis of dementia, death, or the last follow-up day (December 31, 2017).

RESULTS

Depressive symptom presentation, recent depressive disorder, and SCD independently increased dementia incidence with adjusted hazard ratio (aHR) of 1.286 (95% CI:1.255-1.318), 1.697 (95% CI:1.621-1.776), and 1.748 (95% CI: 689-1.808) respectively. Subjects having both SCD and depression had a higher risk (aHR = 2.466, 95% CI:2.383-2.551) of dementia than having depression (aHR = 1.402, 95% CI:1.364-1.441) or SCD (aHR = 1.748, 95% CI:1.689-1.808) alone.

CONCLUSIONS

Depressive symptoms, depressive disorder, and SCD are independent risk factors for dementia. Co-occurring depression and SCD have an additive effect on the risk of dementia; thus, early intervention and close follow up are necessary for patients with co-occurring SCD and depression.

The Analysis of Oxidative Stress Markers May Increase the Accuracy of the Differential Diagnosis of Alzheimer's Disease with and without Depression

Introduction

The aim of work is to assess the usefulness of oxidative stress parameters in the differential diagnosis of dementia of the Alzheimer’s type and dementia of the Alzheimer’s type with coexisting depression.

Methods

The study involved three groups of people: patients with Alzheimer’s disease (AD) (AD; N=27), patients with Alzheimer’s disease and depression (D) (AD+D; N=30), and a control group that consisted of people without dementia and without depression (C; N=24). The assessment of cognitive functioning was carried out using among alia, Auditory Verbal Learning Test and Verbal Fluency Test. Furthermore, we determined the activity of superoxide dismutase (SOD-1) and superoxide anion radical.

Results

Multiple models with different combinations of independent variables showed that SOD together with Rey delayed recall were the best significant predictors of AD with the area under curve (AUC) of 0.893 (p = 0.001) and superoxide anion radical (O2^•−) together with verbal fluency – sharp objects were the best significant predictors of AD +D diagnosis with the AUC of 0.689 (p = 0.034).

Conclusion

This study confirmed the value of neuropsychological diagnosis and analysis of oxidative stress markers in the diagnosis of AD and major depressive disorder (MDD) in the course of AD. The combination of the use of biochemical markers and neuropsychological tests seems particularly important for differential diagnosis.

Sex Differences in Cardiovascular Disease and Cognitive Dysfunction in Rural West Elderly Texans

BACKGROUND

The prevalence of cognitive dysfunction increases in elderly due to cardiovascular disease related risk factors in rural communities like West Texas.

OBJECTIVE

The purpose of this study was to find risk factors of cardiovascular disease (CVD) related to cognitive dysfunction and their impact on elderly adults in rural West Texans.

METHODS

Statistical methods such as Pearson's chi-squared and a multinomial logistic regression were utilized to analyze data. We used SPSS software to detect and understand the nature of the risk factors.

RESULTS

A summary of statistics was obtained by using Pearson's chi-squared test for categorical variables. CVD, diabetes mellitus, and depression were significantly associated with cognitive dysfunction for both males and females (p = 0.0001), whereas anxiety was found to be significantly associated with cognitive dysfunction for females (p = 0.0001). Age group and race/ethnicity were significantly associated with cognitive dysfunction for both males and females (p = 0.0001). By performing a multinomial logistic regression method and controlling for confounders, the significant risk factors (p <  0.05)- age (65- 84 years), diabetes, and memory loss for age-associated cognitive impairment; diabetes for cognitive impairment no dementia; age (65- 84, ≥85 years), CVD, diabetes, depression, memory loss, non-Hispanic Whites, and Black/African-Americans for mild cognitive impairment; and age, memory loss, non-Hispanic Whites, Black/African-Americans, and male gender were found for dementia.

CONCLUSION

CVD related risk factors in developing cognitive dysfunction exist and integrating such risk variables may guide relevant policy interventions to reduce Alzheimer's incidence or dementia in rural communities in West Texans.