Positive Effects of Education on Cognitive Functioning Depend on Clinical Status and Neuropathological Severity

Potential Cognitive Decline Linked to Electronegative L5 in Type 2 Diabetes: A Holo-Hilbert Spectral Analysis

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) have an increased risk of cognitive impairment. In this study, we investigated the effect of L5 - an electronegative subfraction of low-density lipoprotein cholesterol (LDL-C) - on the cognitive function of patients with T2DM.

METHODS

This cross-sectional study included 68 patients with T2DM: 15 with normal cognitive function, 39 with mild cognitive impairment (MCI), and 14 with Alzheimer disease (AD). Cognitive evaluation was performed using the Cognitive Abilities Screening Instrument. We developed a new method - Holo-Hilbert spectral analysis (HHSA) - for analyzing electroencephalography signals. Using HHSA, we investigated the effects of L5 on patients' neural activity.

RESULTS

Our findings suggested that a higher percentage of L5 in LDL-C (L5%) was independently associated with increased risks of MCI and AD in patients with T2DM. A negative correlation was observed between serum L5% and cognitive performance, particularly in the concentration subdomain, in patients with MCI. HHSA revealed that an elevated serum L5% value was correlated with an increase in low-frequency neural oscillations but a reduction in high-frequency oscillations in patients with MCI. However, no correlation was observed between L5, cognitive performance, and neural activity in patients with normal cognitive function or AD.

CONCLUSION

Our findings demonstrate L5 to be an efficient biomarker and electroencephalography/HHSA to be an innovative approach for assessing cognitive function in patients with T2DM. L5 may affect frontal lobe function, leading to concentration deficits. The correlation between L5 and cognitive impairment appears to vary depending on the stage of neurodegeneration.

Cerebrospinal fluid mesencephalic astrocyte-derived neurotrophic factor: A moderating effect on sleep time and cognitive function

BACKGROUND

Sleeping late has been associated with cognitive impairment, and insufficient sleep can affect the secretion of feeding-related cytokines. Feeding-related cytokines may contribute to cognitive deficits resulting from delayed bedtime. Glial cell line-derived neurotrophic factor (GDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF), which are feeding-related neurotrophic factors, have been associated with improved cognitive function and neuroprotective abilities. Enhanced expression of GDNF and MANF is linked to increased energy expenditure and hyperphagia, respectively.

AIMS

This study aimed to investigate the association between cerebrospinal fluid (CSF) GDNF, MANF, cognition, and sleep time and to explore the moderating effects of GDNF and MANF on cognitive impairment in individuals who sleep late.

METHOD

This cross-sectional study included participants (mean age 31.76 ± 10.22 years) who were categorized as ≤23 o'clock sleepers (n = 66) and >23 o'clock sleepers (n = 125) based on sleep time. Cognition was assessed using Montreal Cognitive Assessment (MoCA), and GDNF and MANF levels in CSF were measured.

RESULTS

MANF may play a moderating role in the relationship between sleep time and cognition (R2 = 0.06, β = 0.59, p = 0.031). Age showed a negative correlation with MoCA scores (R2 = 0.08, β = -0.18), while education exhibited a positive correlation (β = 0.17, both p < 0.05). Only ≤23 o'clock sleepers exhibited a negative correlation between MANF levels and BMI (r = -0.35, p = 0.005).

CONCLUSIONS

This study provides hitherto undocumented evidence of the potential protective effect of CSF MANF on cognitive impairment of late sleepers, which suggests that maintaining a regular sleep schedule may contribute to cognition and overall health, with MANF playing a role in this process.

Association between Subjective Cognitive Complaints and Sleep Disturbance among Community-Dwelling Elderly Individuals in Japan

Subjective cognitive complaints (SCCs) are a crucial modifiable risk factor for dementia. There is increasing interest in the association between SCC and sleep disturbance; however, the effects of sleep disturbance on SCC development among community-dwelling elderly individuals in Japan remain unclear. We aimed to cross-sectionally investigate the association between SCC and sleep disturbance, with adjustment for multiple factors related to cognitive decline, among 241 community-dwelling elderly persons without cognitive impairment. The measures were SCCs (Kihon Checklist-Cognitive Function, KCL-CF), sleep disturbance (Japanese version of the Athens Insomnia Scale, AIS-J), general cognitive function (Mini-Mental State Examination), and depressive symptoms (five-item version of the Geriatric Depression Scale [GDS-5]). The following data were collected: sex, age, educational history, whether the participants had visited a medical institution for diseases (hypertension, diabetes, hyperlipidemia, heart disease), and the presence/absence of established risk factors (hearing loss, history of head injury, drinking habits, smoking habits, social isolation, and physical inactivity and activity). Based on the KCL-CF, 96 and 145 participants were considered to have and lack SCCs, respectively. On logistic regression analysis, the AIS-J score and smoking history were significantly associated with SCCs. Our findings suggest that sleep disturbance is associated with SCC development among community-dwelling elderly people in Japan. Evaluating and managing sleep disturbances can be important in preventing SCCs and dementia.

Cognitive dysfunction in diabetes-related foot complications: A cohort study

Objective

Mild-moderate cognitive impairment has been identified in general diabetes, and early evidence indicates cognitive reductions may be more pronounced in those with diabetes-related foot complications (DRFC). Cognitive difficulties may impede treatment engagement and self-management. This requires further explication to optimise patient care and outcomes. The current study aimed to characterise cognitive function in people with DRFC using comprehensive cognitive measures.

Method

This cross-sectional cohort study recruited 80 adult participants (M age  = 63.38, SD = 11.40, range = 30 - 89) from the Royal Melbourne Hospital Diabetic Foot Unit in Victoria, Australia, all with DRFC. Each completed a comprehensive cognitive battery (memory, attention, executive functions) and scores were calculated using age-matched population norms, where available.

Results

On the majority of tasks, DRFC participants performed significantly worse than age-matched norms, with the largest decrements seen in inhibition control, verbal memory, verbal abstract reasoning and working memory. Small to moderate reductions were also seen in visual learning, verbal fluency, processing speed and premorbid functioning. Demographic (lower education, male gender) and clinical factors (higher HbA1c, macrovascular and microvascular disease, longer diabetes duration) were associated with poorer cognitive functioning.

Conclusions

Marked reductions in cognitive functioning were found in individuals with DRFC, predominantly in the domains of verbal memory and executive functioning. Lower education, male gender and indicators of diabetes severity, such as vascular disease, are associated with heightened risk for poorer cognitive functioning. As DRFCs are a serious complication with devastating outcomes if not successfully managed, cognitive barriers to self-management must be addressed to optimise treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01381-4.

Physical exercise and cognition in older adults, a scientific approach scanty reported in Latin America and Caribbean populations

The advancement of public services, including the increased accessibility of health services, has led to a rise in life expectancy globally. As a result, aging populations are becoming more prevalent, raising concerns about cognitive decline. Fortunately, non-pharmacological methods, such as physical exercise, have been shown to mitigate the effects of aging on the brain. In this perspective article, we examined meta-analyses on the impact of physical exercise on cognition in older adults. The results indicate that combined exercise (i.e., aerobic plus strength training), has a significant positive effect on overall cognition and executive function. However, we found a lack of scientific studies on this topic in Latin American and Caribbean countries. Therefore, there is a pressing need for research to identify the feasibility of physical exercise interventions to improve cognitive skills in older adults from these regions.

Measures of cognitive reserve: An umbrella review

Objective: Recently, there has been a growing interest in operationalizing and measuring cognitive reserve (CR) for clinical and research purposes. This umbrella review aims to summarize the existing systematic and meta-analytic reviews about measures of CR. Method: A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the guidelines of Aromataris et al. (2015) to identify the systematic reviews and meta-analysis involving the assessment of CR. The methodological quality of the papers included in this umbrella review was assessed with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR-2) and Specialist Unit for Review Evidence (SURE). Results: Thirty-one reviews were identified, sixteen of which were systematic reviews, and fifteen were meta-analyses. Most of the reviews had a critically low quality, according to AMSTAR-2. The reviews included between two and 135 studies. Most of the papers focused on older adults, mainly those with dementia. CR was measured using one to six proxies, but most considered each proxy separately. The most assessed proxies of CR were education on its own, combined with occupation and/or engagement in activities or combined with parental education, bilingualism, and engagement in activities when four CR proxies were studied. Most of the studies included in higher quality reviews focused on three proxies, with education and engagement in activities being the most evaluated using CR questionnaires. Conclusion: Despite the growing interest in measuring CR, its operationalization did not improve since the last umbrella review in this field.

Multiple socioeconomic risks and cognitive impairment among older men and women in India

Introduction

Socioeconomic status (SES) is negatively associated with innumerable health outcomes, including cognitive functioning. Yet much remains undiscovered about SES patterns in later-life cognition in low-and middle-income countries (LMICs). The purpose of this study was to examine the association between separate and combined socioconomic risks and cognitive impairment among older adults in India. Further, given gender disparities in later life cognitive functioning and SES, the study examines the associations between socioeconomic risks and cognitive impairment separately, for older men and women.

Methods

Data come from the 2017-18, first wave of the Longitudinal Aging Study in India (LASI), with 31,464 older adults aged 60 years and above. Cognitive impairment was assessed using multiple broad measures of memory, orientation, arithmetic function, and visuo-spatial construction skills. We present descriptive statistics along with cross-tabulation of the outcome variable. Additionally, binary logistic regression analysis was used to test the association between outcome and explanatory variables. SES is measured using education, paid work status, and household wealth measured using monthly per-capita consumption expenditure (MPCE).

Results

A proportion of 7.14% of the older men and 20.03% of older women reported cognitive impairment. The odds of cognitive impairment were higher among uneducated older men and women, and older men and women in lowest wealth quintile. Surprisingly, older women without current or prior work history report lower odds of cognitive impairment compared to their peers in labor force. While odds of cognitive impairment are higher among non-working older men, this association is not statistically significant. In older men, the odds of cognitive impairment were 5.34, 7.14, and 13.05 times higher with one, two, and three risk factors, respectively, compared with those with no risk exposure. A similar trend was observed for women but with comparatively lower odds.

Conclusions

Our findings underscore the need to distinguish between varying elements of SES to construct "upstream" health policies and programs that redistribute resources. In particular, the findings support the use of multiple SES indicators in identifying older adults most susceptible to cognitive deficits, and planning gender-based interventions to improve cognitive health in late life.

Recent contributions to the field of subjective cognitive decline in aging: A literature review

Subjective cognitive decline (SCD) is defined as self-experienced, persistent concerns of decline in cognitive capacity in the context of normal performance on objective cognitive measures. Although SCD was initially thought to represent the "worried well," these concerns can be linked to subtle brain changes prior to changes in objective cognitive performance and, therefore, in some individuals, SCD may represent the early stages of an underlying neurodegenerative disease process (e.g., Alzheimer's disease). The field of SCD research has expanded rapidly over the years, and this review aims to provide an update on new advances in, and contributions to, the field of SCD in key areas and themes identified by researchers in this field as particularly important and impactful. First, we highlight recent studies examining sociodemographic and genetic risk factors for SCD, including explorations of SCD across racial and ethnic minoritized groups, and examinations of sex and gender considerations. Next, we review new findings on relationships between SCD and in vivo markers of pathophysiology, utilizing neuroimaging and biofluid data, as well as associations between SCD and objective cognitive tests and neuropsychiatric measures. Finally, we summarize recent work on interventions for SCD and areas of future growth in the field of SCD.

Higher education level as a protective factor against executive dysfunction in patients with epilepsy in Mataram, Indonesia

OBJECTIVE

Since the concept of cognitive reserve is applicable in epilepsy-associated cognitive impairment, the role of cognitive reserve components as a protective factor against epilepsy-associated executive dysfunction needs further investigation. This study aimed at investigating the association between cognitive reserve components and the frequency of epilepsy-associated executive dysfunction in Mataram, Indonesia.

METHODS

This case-control study involved both epilepsy outpatient and healthy participants recruited consecutively in 5 hospitals in Mataram, between October 2021 and September 2022. Data on sociodemographic, cognitive reserve components, and executive function status were collected from both groups, while data on seizure were collected only from epilepsy participants. The association between cognitive reserve components and the frequency of epilepsy-associated executive dysfunction was tested using logistic regression.

RESULTS

A total of 119 epilepsy patients and 93 healthy participants were recruited. The frequency of epilepsy-associated executive dysfunction was 50.4%. Multivariate logistic regression analysis showed that higher education level was the only cognitive reserve component protective against epilepsy-associated executive dysfunction (odds ratio [OR]: 3.36; 95% confidence interval [CI]: 1.33 - 8.50).

CONCLUSION

A high frequency of epilepsy-associated executive dysfunction was observed in Mataram. Higher education level was a cognitive reserve component protective against executive dysfunction in these patients.

The Association Between Temporal Atrophy and Episodic Memory Is Moderated by Education in a Multi-Center Memory Clinic Sample

BACKGROUND

Cognitive reserve (CR) is hypothesized to partially explain the discrepancy between Alzheimer's disease related brain pathology and cognitive performance. Educational attainment is often used as a proxy for CR.

OBJECTIVE

To examine the association of years of education and the relationship between atrophy in the medial temporal lobe and episodic memory, in a cross-sectional ecological multi-center memory clinic cohort.

METHODS

Included patients (n = 702) had undergone memory clinic examination and were diagnosed with subjective cognitive impairment (n = 99), mild cognitive impairment (n = 471), or dementia (n = 132). Total years of education were used as a moderating variable and neuropathology was operationalized as visual ratings of medial temporal lobe atrophy (MTA) on magnetic resonance imaging and computer tomography images. Weighted least squares regression and multiple regression were used to analyze moderation and the effect of education separately by diagnostic group. A composite score of two episodic memory tests constituted the dependent variable.

RESULTS

After controlling for age and gender the interaction term between MTA and years of education was significant indicating moderation. In particular, the regression model showed that at low levels of MTA, high education individuals had better episodic memory performance. However, at higher MTA levels, high education individuals had the lowest episodic memory performance. Education had a significant positive effect on episodic memory in SCI and MCI, but not dementia.

CONCLUSION

These results extend the findings of education moderating the effect of MTA on cognition to a naturalistic memory clinic setting. Implications of the findings for theories on CR are discussed.

Psychological resilience, activities of daily living, and cognitive functioning among older male Tekun adults in rural long-term care facilities in China

Most of the rural long-term care (LTC) facilities in China are ill-equipped to manage the physical and psychological needs of older residents with dementia. These facilities mostly consist of older male Tekun (socially and economically vulnerable) adults. Preventing or delaying the onset of dementia is especially crucial for these older Tekun adults. A sample of 711 older male Tekun adults from rural LTC facilities in the Anhui province of China was used to investigate the association between psychological resilience and cognitive functioning, and to examine the moderating effect of activities of daily living (ADLs) on that association. Linear and quantile regression found that resilience was positively associated with cognitive functioning for the total sample, with a greater effect among those with a lower level of cognitive functioning. The benefit of resilience on cognitive functioning was observed only in participants with disability in ADLs. Our findings present evidence in support of interventions to foster psychological resilience and potentially improve cognitive functioning among vulnerable older adults. Resilience-promoting intervention is a strength-based approach that aligns with social work values and can be used in practice. The implications for social work practice were discussed.

Interactive Effects of Methionine and Lead Intake on Cognitive Function among Chinese Adults

The association between methionine intake and cognitive function is inconclusive. We aimed to assess the association between methionine intake and cognitive function in Chinese adults and to explore the interaction between methionine and lead intake. Data from 4852 adults aged ≥55 years from the China Health and Nutrition Survey were used. Cognitive function was measured in 1997, 2000, 2004, and 2006. A 3-day, 24-hour recall was used to assess methionine and lead intake from different protein sources. Multivariable mixed linear regression was used in the analyses. Total methionine intake was positively correlated with cognition. There was a significant interaction between animal methionine and lead intakes. In subgroup analyses, across the quartiles of animal methionine intake, the regression coefficients (95% CI) for global cognition were 0.00, 0.57 (0.17 to 0.98), 1.18 (0.73 to 1.62), and 1.80 (1.31 to 2.29), respectively, while they were 0.00, -0.73 (-1.12 to -0.34), -0.83 (-1.26 to -0.41), and -1.72 (-2.22 to -1.22) across the quartiles of plant methionine intake, respectivelyThe association between animal methionine intake and cognition was stronger among adults with a low lead intake. In conclusion, animal methionine and plant methionine intake were positively and inversely associated with cognition, respectively. Lead intake modified the association between animal methionine intake and cognition.

Depressive Symptoms and Cognitive Decline Among Chinese Rural Elderly Individuals: A Longitudinal Study With 2-Year Follow-Up

Background

Depressive symptoms and mild cognitive impairment (MCI) are highly prevalent in rural China. The study aimed to investigate the longitudinal associations between changes in depressive symptoms and cognitive decline and MCI incidence among Chinese rural elderly individuals.

Methods

A 2-year follow-up study was conducted among 1,477 participants from the Anhui Healthy Longevity Survey (AHLS). Depressive symptoms were assessed by the 9-item Patient Health Questionnaire (PHQ-9), and cognitive status was evaluated by the Mini Mental State Examination (MMSE). Multivariable linear regression and logistic regression were employed.

Results

Every 1-unit PHQ-9 score increase was significantly associated with more cognitive decline (β = 0.157, 95% CI: 0.092, 0.221, p &lt; 0.001) and a higher risk of MCI incidence (OR = 1.063, 95% CI: 1.025, 1.103, p = 0.001). The participants who experienced worsening of depression symptoms had a larger decline in the 2-year MMSE score (β = 0.650, 95% CI: 0.039, 1.261, p = 0.037) and elevated risks of incident MCI (OR = 1.573, 95% CI: 1.113, 2.223, p = 0.010).

Limitations

Screening tools rather than standard diagnostic procedures were used in the study. Moreover, the long-term associations still need further exploration since the follow-up time was short.

Conclusions

Increased depressive symptoms were associated with more cognitive decline and higher risks of incident MCI among Chinese rural residents.

Effects of cognitive reserve proxies on cognitive function and frontoparietal control network in subjects with white matter hyperintensities: A cross-sectional functional magnetic resonance imaging study

AIMS

This study aimed to analyze the potential association between cognition reserve (CR) components, including education, working activity, and leisure time activity, and cognitive function in subjects with white matter hyperintensities (WMH). The study also explored the role of the frontoparietal control network (FPCN) in such association.

METHODS

White matter hyperintensities subjects with and without cognitive impairment (CI) were evaluated with multimodal magnetic resonance imaging, neuropsychological testing, and CR survey. FPCN patterns were assessed with dorsolateral prefrontal cortex seed-based functional connectivity analysis.

RESULTS

Education was positively associated with cognitive function in WMH subjects with or without CI, whereas working activity and leisure time activity were positively associated with cognitive function only in those without CI. Similarly, education was associated with bilateral FPCN in both WMH groups, whereas working activity and leisure time activity were associated with bilateral FPCN mainly in the group without CI. Furthermore, FPCN partially mediated the association between education and cognitive function in both WMH groups.

CONCLUSION

Education showed a positive impact on cognitive function in WMH subjects regardless of their cognitive status, whereas working activity and leisure time activity exhibited beneficial effects only in those without CI. The FPCN mediated the beneficial effect of education on cognitive function.