Low Cognitive Reserve Research Articles

Lifelong Cognitive Reserve, Imaging Markers of Brain Aging, and Cognitive Function in Dementia-Free Rural Older Adults: A Population-Based Study.

Cognitive reserve (CR) partly explains cognitive variability in the presence of pathological brain aging. We investigated the interplay of lifelong CR with age, sex, and brain aging markers in cognitive phenotypes among older adults with very limited education. This population-based cross-sectional study included 179 dementia-free participants (age ≥65 years; 39.7% women; 67.0% had no or elementary education) examined in 2014-2016. We assessed lacunes and volumes of hippocampus, ventricles, grey matter, white matter (WM), and white matter hyperintensities. Lifelong CR score was generated from six lifespan intellectual factors (e.g., education and social support). We used Mini-Mental State Examination (MMSE) score to assess cognition and Petersen's criteria to define mild cognitive impairment (MCI). Data were analyzed using general linear and logistic models. The association of higher lifelong CR score (range: -4.0-5.0) with higher MMSE score was stronger in women (multivariable-adjusted β-coefficient and 95% CI: 1.75;0.99-2.51) than in men (0.68;0.33-1.03) (pinteraction = 0.006). The association of higher CR with MCI (multivariable-adjusted odds ratio and 95% CI: 0.77;0.60-0.99) did not vary by age or sex. Among participants with low CR (<1.4[median]), greater hippocampal and WM volumes were related to higher MMSE scores with multivariable-adjusted β-coefficients being 1.77(0.41-3.13) and 0.44(0.15-0.74); the corresponding figures in those with high CR were 0.15(-0.76-1.07) and -0.17(-0.41-0.07) (pinteraction <0.01). There was no statistical interaction of CR with MRI markers on MCI. Greater lifelong CR capacity is associated with better late-life cognition among people with limited education, possibly by compensating for impact of neurodegeneration.

Education reduces cognitive dysfunction in Alzheimer's disease by changing regional cerebral perfusion: An in-vivo arterial spin labeling study.

Formal education and other cognitive challenges influence brain structure and improve function. It is believed that cognitive activities create a cognitive reserve (CR) that can slow the decline due to aging and neurodegenerative diseases. This study investigated alterations of regional cerebral blood flow (rCBF) associated with high and low CR in different stages of Alzheimer's disease (AD) and examined whether rCBF alteration mediates the relationship between education and cognitive performance. Patients with AD or amnestic mild cognitive impairment (aMCI) and healthy controls were divided into low cognitive reserve (LCR) and high cognitive reserve (HCR) subgroups according to median of education years (≤ 9 vs. > 9 years). The final study population included 89 AD patients (67 LCR, 22 HCR), 74 aMCI patients (44 LCR, 30 HCR), and 66 healthy controls (29 LCR, 37 HCR). All subjects were examined by arterial spin labeling magnetic resonance imaging and a neurocognitive test battery. rCBF was compared among groups by two-way analysis of variance. Mediation analyses were used to explore the relationships among education, rCBF, and cognitive test scores. There were significant interaction effects of disease state (AD, aMCI, HC) and education level (LCR, HCR) on CBF in right hippocampus, posterior cingulate cortex, and right inferior parietal cortex (R_IPC). Education regulated episodic memory score by influencing right hippocampal CBF in HC_HCR and aMCI_HCR subgroups. Our results indicate that the protective effect of education against cognitive dysfunction in early-stage AD is mediated at least partially by altered CBF in right hippocampus.

Sleep, 24-Hour Activity Rhythms, and Cognitive Reserve: A Population-Based Study.

The cognitive reserve hypothesis aims to explain individual differences in susceptibility to the functional impact of dementia-related pathology. Previous research suggested that poor subjective sleep may be associated with a lower cognitive reserve. The objective was to investigate if actigraphy-estimated sleep and 24-hour activity rhythms are associated with cognitive reserve. This cross-sectional study included 1,002 participants from the Rotterdam Study (mean age: 65.0 years, standard deviation (SD): 7.1) who were assessed with actigraphy, five cognitive tests, and brain-MRI between 2009- 2014. Sleep and 24-hour activity rhythms were measured using actigraphy (mean days: 6.7, SD: 0.5). Cognitive reserve was defined as a latent variable that captures variance across cognitive tests, while adjusting for age, sex, education, total brain volume, intracranial volume, and white matter hyperintensity volume. Associations of sleep and 24-hour activity rhythms with cognitive reserve were assessed using structural equation models. Longer sleep onset latency (adjusted mean difference: - 0.16, 95% CI: - 0.24; - 0.08) and lower sleep efficiency (0.14, 95% CI: 0.05; 0.22) were associated with lower cognitive reserve. Total sleep time and wake after sleep onset were not significantly associated with cognitive reserve. After mutual adjustment, only the association of longer sleep onset latency remained significant (- 0.12, 95% CI: - 0.20; - 0.04). The 24-hour activity rhythm was not significantly associated with cognitive reserve. In conclusion, our study suggests that longer sleep onset latency is particularly associated with lower cognitive reserve. Future longitudinal work is needed to assess whether shortening the sleep onset latency could enhance cognitive reserve, in order to limit the susceptibility to the functional impact of dementia-related pathology.

Cognitive and brain reserve predict decline in adverse driving behaviors among cognitively normal older adults.

Daily driving is a multi-faceted, real-world, behavioral measure of cognitive functioning requiring multiple cognitive domains working synergistically to complete this instrumental activity of daily living. As the global population of older adult continues to grow, motor vehicle crashes become more frequent among this demographic. Cognitive reserve (CR) is the brain's adaptability or functional robustness despite damage, while brain reserve (BR) refers the structural, neuroanatomical resources. This study examined whether CR and BR predicted changes in adverse driving behaviors in cognitively normal older adults. Cognitively normal older adults (Clinical Dementia Rating 0) were enrolled from longitudinal studies at the Knight Alzheimer's Disease Research Center at Washington University. Participants (n = 186) were ≥65 years of age, required to have Magnetic Resonance Imaging (MRI) data, neuropsychological testing data, and at least one full year of naturalistic driving data prior to the beginning of COVID-19 lockdown in the United States (March 2020) as measured by Driving Real World In-vehicle Evaluation System (DRIVES). Findings suggest numerous changes in driving behaviors over time were predicted by increased hippocampal and whole brain atrophy, as well as lower CR scores as proxied by the Wide Range Achievement Test 4. These changes indicate that those with lower BR and CR are more likely to reduce their driving exposure and limit trips as they age and may be more likely to avoid highways where speeding and aggressive maneuvers frequently occur.

Adaptación argentina del Cuestionario de Reserva Cognitiva: CRC-a

Cognitive reserve (CR) refers to the level of adaptability of cognition after brain changes. It is based on processes that allow the activation of new synaptic connections after neurodegeneration, which permits to better withstand the consequences. This reserve is constituted by the interaction of innate individual characteristics (intrauterine or genetically determined) and the exposure to different life experiences. It begins its development in early stages of life and continues its transformation up to advances ages. The sociodemographic variables reported as the main ones to build the reserve are education, leisure activities, lifestyle, socioeconomic level and intelligence. Several studies have considered it as a protective factor for Alzheimer's Disease (AD). Subjects with high levels of CR have lower prevalence and incidence of AD in comparison to those with low levels of reserve. CR would lead to a late onset of symptoms, despite not having any effect on the underlying pathophysiological process of the disease. The reserve would not prevent AD from developing, but it would compensate the symptoms and, therefore, delay their onset. In some cases, there is such compensation that the symptoms do not manifest. There is no validated instrument available for the Argentinian region that allows to measure this construct. The aim of this study is to adapt the Cognitive Reserve Questionnaire to the Argentinian population, to establish cut-off scores to distinguish between low, medium, high and superior levels of CR and analyze which variables could predict the total reserve score. The modifications introduced in the adaptation were evaluated through an expert judgment process. A total of 177 healthy subjects completed the Cognitive Reserve Questionnaire in its Argentinian adaptation (CRQ-a). Through the measure of quartiles, cut-off scores were established to determine low, medium, high and superior levels of the reserve. A lineal regression was made to evaluate if age, education, and sex might predict the level of CR. Three of the eight total dimensions and 16 of the 33 total items that make up the original questionnaire were modified. The mean of the total score obtained by the sample from the questionnaire was 15.06 with SD = 3.42. Scores under 13 reflected low CR levels, scores between 13 and 16 reflected medium levels, scores between 16 and 20 reflected high levels, and scores above 20 reflected superior levels. Education turned out to be the only predictor variable for the level of CR. Although differences were found between groups of different sex, this variable turned out to be not predictive. The CRQ-a is the first instrument for the Argentinian population to measure the level of the reserve. It allows to quickly explore different dimensions, considered as the most relevant for its formation. These are: formal education, courses, parents' formal education, employment, musical training, languages, reading activity and intellectual games. In patients with AD, is particularly important to have a measure for CR to prepare interventions for those subjects whose reserve levels are perceived as low, aiming to delay and, when possible, prevent the clinical manifestation of the disease. Its validation would open future lines of research on possible interventions for the prevention of diseases such as AD. https://doi.org/10.16888/interd.2023.40.1.8

The association between low cognitive reserve and subjective memory complaints in functionally independent older women

BackgroundSeveral factors have been found to defend against pathologic cognitive decline in aging (i.e., cognitive reserve [CR]); however, other factors, including subjective memory complaints (SMC) and decreased functionality are considered early indicators of underlying neurocognitive dysfunction. Despite these known associations, the relationship between the presence of CR and SMC remains equivocal. This study sought to determine the relationship between objectively measured CR and SMC in a sample of functionally independent older women. MethodsThis cross-sectional study recruited women aged ≥60 years who attended fitness or continuing education programs at the University for Seniors in Mexico City. Participants underwent a battery of physical and cognitive evaluations, including the Cognitive Reserve Questionnaire (CRQ), and were asked probing questions used to identify the presence of SMC. ResultsThe 269 participants had a median age of 69 years; most were single (40.5 %), lived alone (32.7 %), retired (58.2 %), well-educated (≥12 years of education), and functionally independent (89.2 %). 62 % scored “high” on the CRQ, while 9.3 % scored “low”. After adjusting for multiple covariates, an independent association between CRQ score and the probability to have SMC was found (adjusted OR = 0.87, 95% CI 0.80–0.95, p-value = 0.002). ConclusionsThis study identified a relationship between low CR and the presence of SMC, independently of the cognitive function and motoric marker of muscle strength (i.e., low gait speed and handgrip strength) in functionally independent older women over 60y. This relationship remains independent of other variables such as age, symptoms of depression and instrumented activities of daily living.

Cognitive reserve profiles are associated with outcome in schizophrenia.

Cognitive reserve (CR), the brain's ability to cope with brain pathology to minimize symptoms, could explain the heterogeneity of outcomes in neuropsychiatric disorders, however it is still rarely investigated in schizophrenia. Indeed, this study aims to classify CR in this disorder and evaluate its impact on neurocognitive and socio-cognitive performance and daily functioning. A group of 106 patients diagnosed with schizophrenia was enrolled and assessed in these aereas: neurocognition, Theory of Mind (ToM) and daily functioning. A composite CR score was determined through an integration of the intelligence quotient and education and leisure activities. CR profiles were classified with a two-step cluster analysis and differences among clusters were determined with an analysis of variance (ANOVA). The cluster analysis was identified with three CR profiles characterized, respectively, by high, medium and low CR. ANOVA analysis showed significant differences on neurocognition, ToM and daily functioning between the clusters: people with higher CR reached significantly superior scores. This study suggests that greater general cognitive resources could act as a buffer against the effect of brain pathology, allowing patients to have a better cognitive performance, social outcome and quality of life.

Cognitive Reserve Modulates Brain Structure and Cortical Architecture in the Alzheimer's Disease.

Cognitive reserve (CR) explains the individual resilience to neurodegeneration. The present study investigated the effect of CR in modulating brain cortical architecture. 278 individuals [110 Alzheimer's disease (AD), 104 amnestic mild cognitive impairment (aMCI) due to AD, 64 healthy subjects (HS)] underwent a neuropsychological evaluation and 3T-MRI. Cortical thickness (CTh) and fractal dimension (FD) were assessed. Years of formal education were used as an index of CR by which participants were divided into high and low CR (HCR and LCR). Within-group differences in cortical architecture were assessed as a function of CR. Associations between cognitive scores and cortical measures were also evaluated. aMCI-HCR compared to aMCI-LCR patients showed significant decrease of CTh in the right temporal and in the left prefrontal lobe. Moreover, they showed increased FD in the right temporal and in the left temporo-parietal lobes. Patients with AD-HCR showed reduced CTh in several brain areas and reduced FD in the left temporal cortices when compared with AD-LCR subjects. HS-HCR showed a significant increase of CTh in prefrontal areas bilaterally, and in the right parieto-occipital cortices. Finally, aMCI-HCR showed significant positive associations between brain measures and memory and executive performance. CR modulates the cortical architecture at pre-dementia stage only. Indeed, only patients with aMCI showed both atrophy (likely due to neurodegeneration) alongside richer brain folding (likely due to reserve mechanisms) in temporo-parietal areas. This opposite trend was not observed in AD and HS. Our data confirm the existence of a limited time-window for CR modulation at the aMCI stage.

Association of AK4 Protein From Stem Cell-Derived Neurons With Cognitive Reserve: An Autopsy Study.

Identifying protein targets that provide cognitive reserve is a strategy to prevent and treat Alzheimer disease and Alzheimer disease related dementias (AD/ADRD). Previous studies using bulk human brain tissue reported 12 proteins associated with cognitive reserve. This study examined whether the same proteins from induced neurons (iNs) are associated with cognitive reserve of their human donors. Induced pluripotent stem cell (iPSC) lines were generated from cryopreserved peripheral blood mononuclear cells of older adults who were autopsied as part of the Religious Orders Study or Rush Memory and Aging Project. Neurons were induced from iPSCs using a standard neurogenin2 protocol. Tandem mass tag proteomics analyses were conducted on iNs day 21. Cognitive reserve of their human donors was measured as person-specific slopes of cognitive change not accounted for by common neuropathologies. The 53 human donors died at a mean age of 91 years, all were non-Latino White, and 36 (67.9%) were female. Eighteen were diagnosed with Alzheimer dementia proximate to death, and 34 had pathologic AD diagnosis at autopsy. Approximately 60% of the donors had above-average cognitive reserve such that their cognition declined slower than an average person with comparable burdens of neuropathologies. Eight of the 12 candidate proteins were quantified in iNs proteomics analyses. Higher adenylate kinase 4 (AK4) expression in iNs was associated with lower cognitive reserve, consistent with the previous report for brain AK4 expression. By replicating cortical protein associations with cognitive reserve in human iNs, these data provide a valuable molecular readout for studying complex clinical phenotypes such as cognitive reserve in a dish.

Avoidant Coping Is Associated with Quality of Life in Persons with Multiple Sclerosis with High Cognitive Reserve

The goal of this study was to determine the impact of the relationship between cognitive reserve and coping strategy on quality of life (QoL) outcomes in persons with MS (PwMS) across multiple domains. We examined the effect of the interactions between coping style and cognitive reserve on QoL and disease burden in 97 persons with MS (PwMS). Coping strategy, either active or avoidant, was measured using the COPE inventory. We defined cognitive reserve as a composite measure of years of education and scores on the Shipley-2 Vocabulary subtest. QoL and disease burden were assessed using the Functional Assessment of MS (FAMS) scale and the Expanded Disability Status Scale, respectively. We examined both the FAMS individual subscales and the overall QoL score. For those with higher cognitive reserve, greater avoidant coping was associated with lower QoL for the thinking and fatigue subscale (p < 0.001) and poorer overall QoL (p = 0.03); greater active coping was associated with poorer QoL for mobility (p = 0.001). However, these associations did not hold for those with lower cognitive reserve. Furthermore, there were no associations between coping strategy and cognitive reserve with disease burden. This study extends previous findings by demonstrating that avoidant coping, rather than active coping, is associated with poorer thinking and fatigue and overall QoL only for PwMS with greater cognitive reserve. Counseling PwMS on the impact of coping strategies on QoL outcomes, especially for those with greater cognitive reserve, may improve quality of life outcomes in this population.

The interactive support of cognitive reserve and semantic knowledge in proper name retrieval

ABSTRACT Cognitive reserve (CR) refers to acquired experience that modulates resistance to physiological aging or brain damage. A relatively neglected issue is whether or not CR affects cognitive abilities equally. One relevant component of CR seems to be the richness of connections in semantic knowledge. We examined, in N = 66 healthy older adults, the potential influence of CR and semantic knowledge on the ability to retrieve proper names and common nouns. These two name categories have different semantic organisations, whereby proper names are characterised by a weaker semantic link to the information they refer to. Controlling for age, CR and semantic knowledge were linearly and positively associated with common noun retrieval. On the other hand, CR assisted proper name retrieval in older adults with a weaker semantic profile, while semantic knowledge assisted proper name retrieval in older adults with lower CR. This study contributes to define the cognitive underpinnings of CR.

Phonemic fluency in post-ICU patients after severe COVID-19 infection: The role of cognitive reserve

IntroductionCognitive function may be impaired in COVID-19 patients, especially in executive functions such as phonemic fluency. Among risk factors, inflammation during hospitalization is related with worse cognitive performance in the long term. On the other side, it has been shown that cognitive reserve (CR) protects against cognitive impairment associated with brain damage, psychiatric disorders and neurodegenerative diseases.ObjectivesOur aim is to study the protective role of cognitive reserve in phonemic fluency to inflammation after SARS-CoV-2 infection.MethodsWe enrolled a cohort of 102 severe SARS-CoV-2 survivors after Intensive Care Unit (ICU) discharge and 58 agreed to participate in this 6-month follow-up study. Patients with previously known cognitive impairment were excluded. Demographic, clinical and laboratory data were collected. To assess the phonemic fluency, we used the Controlled Oral Word Association Test (COWAT) controlling the effects of age and education. Inflammation was recorded according to the number of days with high CRP. ANCOVA analyses were used to test the effect of interaction between medical variables and cognitive reserve on phonemic fluency.ResultsThe COVID-19 inflammation interacted with CR in phonemic fluency (F= 6.47, p= 0.01), with worse performance in patients with low CR (mean 16.7 (10.2-23.3)) than those with high CR (mean 37.7 (34.3-41.2)) in function of number of days with high PCR during ICU stay.ConclusionsThe role of the cognitive reserve is important to reduce the cognitive impairment related with COVID-19 inflammation in post-ICU patients.DisclosureNo significant relationships.

Cognitive reserve, neurocognitive performance, and high-order resting-state networks in cognitively unimpaired aging

Cognitive Reserve (CR) is considered a protective factor during the aging process. However, although CR is a multifactorial construct, it has been operationalized in a unitary way (years of formal education or IQ). In the present study, a validated measure to categorize CR holistically (Cognitive Reserve Index Questionnaire) was used to evaluate the resting-state functional connectivity in 77 cognitively unimpaired participants aged 50 years and over with high and low CR, and matched brain global atrophy levels. The connectivity of networks linked to attentional (Dorsal Attention Network -DAN-) and executive (Frontal-Parietal Control Network -FPCN-) processes were evaluated by the combination of Independent Component Analysis and seed-based approaches, since these networks have been proposed as candidates to underlie the protective effect of CR in the aging context. Participants with high CR showed an increase of the connectivity in the FPCN and a decrease in the DAN with respect to the low CR group, correlating with neuropsychological scores and supporting that high CR is related to a better neurocognitive preservation during aging.

Cognitive Reserve and Related Constructs: A Unified Framework Across Cognitive and Brain Dimensions of Aging.

Cognitive reserve and related constructs are valuable for aging-related research, but consistency and clarification of terms is needed as there is still no universally agreed upon nomenclature. We propose a new set of definitions for the concepts of reserve, maintenance, and resilience, and we invoke parallel concepts for each that are applicable to cognition and to brain. Our definitions of reserve and resilience correspond reasonably well to dictionary definitions of these terms. We demonstrate logical/methodological problems that arise from incongruence between commonly used conceptual and operational definitions. In our view, cognitive reserve should be defined conceptually as one’s total cognitive resources at a given point in time. IQ and education are examples of common operational definitions (often referred to as proxies) of cognitive reserve. Many researchers define cognitive reserve conceptually as a property that allows for performing better than expected cognitively in the face of aging or pathology. Performing better than expected is demonstrated statistically by interactions in which the moderator is typically IQ or education. The result is an irreconcilable situation in which cognitive reserve is both the moderator and the moderation effect itself. Our proposed nomenclature resolves this logical inconsistency by defining performing better than expected as cognitive resilience. Thus, in our usage, we would test the hypothesis that high cognitive reserve confers greater cognitive resilience. Operational definitions (so-called proxies) should not conflate factors that may influence reserve—such as occupational complexity or engagement in cognitive activities—with cognitive reserve itself. Because resources may be depleted with aging or pathology, one’s level of cognitive reserve may change over time and will be dependent on when assessment takes place. Therefore, in addition to cognitive reserve and cognitive resilience, we introduce maintenance of cognitive reserve as a parallel to brain maintenance. If, however, education is the measure of reserve in older adults, it precludes assessing change or maintenance of reserve. Finally, we discuss consideration of resistance as a subcategory of resilience, reverse causation, use of residual scores to assess performing better than expected given some adverse factor, and what constitutes high vs. low cognitive reserve across different studies.

The Effect of Propofol versus Sevoflurane on Postoperative Delirium in Parkinson's Disease Patients Undergoing Deep Brain Stimulation Surgery: An Observational Study.

Background: The selection of the maintenance of general anesthesia may affect the development of postoperative delirium (POD), notably for Parkinson’s disease (PD) patients, due to their lower cognitive reserve. The present study was designed to compare the potential impact of propofol vs. sevoflurane based general anesthesia maintenance methods on the development of POD in PD patients following deep brain stimulation (DBS) surgery. Methods: A total of 125 PD patients who were scheduled to undergo DBS surgery were randomly divided into the propofol (n = 63) and the sevoflurane groups (n = 62). The patients in the two groups randomly received propofol- or sevoflurane-based general anesthesia. The Confusion Assessment Method (CAM) was employed by an investigator who was blinded to the anesthesia regimen and was administered twice per day from postoperative day 1 until discharge. Results: The incidence of POD was 22.22% (14/63) with propofol anesthesia and 20.97% (13/62) with sevoflurane anesthesia (p = 0.865). In addition, no difference was noted in the duration and severity of delirium between the propofol and sevoflurane groups. Conclusions: In the present study, propofol- and sevoflurane-based general anesthesia exhibited comparable results with regard to the POD incidence in PD patients undergoing deep brain stimulation surgery.

Morphological processing of complex and simple pseudo-words in adults and older adults

AbstractThe role of morphemes in lexical recognition has been extensively explored in recent years, although the evidence from older adults is extremely scarce. In this study, we carry out a lexical decision task to assess the interference generated by morphological composition of pseudo-words (i.e., the longer and more error prone decisions on pseudo-words made up of morphemes in comparison to pseudo-words without morphological appearance) in a group of young and older adults (mean = 74 years). The results show the expected effect on both response latencies and error rates for both groups. The effect of imageability is also significant. The specific results for the older adults show an interaction between the morphological effect and cognitive reserve: older adults with higher levels of cognitive reserve are more sensitive to morphological interference than older adults with lower cognitive reserve. The overall results are interpreted based on current models of morphological processing and aging.

High lifelong cognitive reserve prolongs disability-free survival: The role of cognitive function.

The association between cognitive reserve (CR) and survival with independence is unknown. We examined whether lifelong CR accumulation is associated with disability-free survival and explored the extent to which cognitive function mediates this association. Within the Rush Memory and Aging Project, 1633 dementia- and disability-free participants were followed annually for up to 22 years. Lifelong CR including education, early-/mid-/late-life cognitive activities, and late-life social activity was assessed and tertiled. CR score was dose-dependently associated with disability/death (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.93-0.99). Compared to low CR, the HR (95% CI) of disability/death was 0.82 (0.70-0.95) for high CR. The median disability-free survival time was prolonged by 0.99 (95% CI 0.28-1.71) years for participants with high CR. Cognitive function mediated 35.7% of the association between CR and disability-free survival. High lifelong CR was associated with prolonged disability-free survival. Cognitive function mediates about one-third of this association. Our findings underscore the importance of CR for healthy aging.

Cognition and Cognitive Reserve in Cochlear Implant Recipients.

At present, dementia is a hot topic. Hearing loss is considered to be a modifiable risk factor for cognitive decline. The underlying mechanism remains unclear and might be mediated by socioeconomic and psychosocial factors. Cochlear implantation has been shown not only to restore auditory abilities, but also to decrease mental distress and to improve cognitive functions in people with severe hearing impairment. However, the promising results need to be confirmed. In a prospective single-center study, we tested the neurocognitive abilities of a large group of 71 subjects with bilateral severe hearing impairment with a mean age of 66.03 (SD = 9.15) preoperatively and 6, 12, and 24 months after cochlear implantation using a comprehensive non-auditory computer-based test battery, and we also assessed the cognitive reserve (CR) [Cognitive Reserve Index (CRI)], health-related quality of life (QoL) (Nijmegen Cochlear Implant Questionnaire), and depression (Geriatric Depression Scale-15). Cognitive functions significantly increased after 6 months in attention (p = 0.00004), working memory (operation span task; p = 0.002), and inhibition (p = 0.0002); and after 12 months in recall (p = 0.003) and verbal fluency (p = 0.0048), and remained stable up to 24 months (p ≥ 0.06). The CR positively correlated with cognitive functions pre- and post-operatively (both p < 0.005), but postoperative improvement in cognition was better in subjects with poor CR (p = 0.003). Depression had only a slight influence on one subtest. No correlation was found among cognitive skills, quality of life, and speech perception (each p ≥ 0.05). Cochlear implantation creates an enriched environment stimulating the plasticity of the brain with a global positive impact on neurocognitive functions, especially in subjects with poor preoperative cognitive performance and low cognitive reserve.

The flexibility of cognitive reserve in regulating the frontoparietal control network and cognitive function in subjects with white matter hyperintensities

High cognitive reserve (CR) protects against cognitive decline in individuals with white matter hyperintensities (WMH). However, the functional mechanisms remain relatively unknown. This work aimed to explore the effects of CR on the frontoparietal control network (FPCN) and cognitive function in subjects with WMH. One hundred and thirty-seven subjects with WMH and 95 control subjects without WMH underwent neuropsychological testing, CR assessments, and multimodal magnetic resonance imaging (MRI) scanning. A mixed analysis of covariance with CR level (high CR vs. low CR) and WMH status (with WMH vs. without WMH) as fixed factors was performed on the FPCN. WMH volume was negatively correlated with global cognitive function in subjects with low CR not in those with high CR, suggesting a buffering effect of high CR. An interaction between CR and WMH was detected on the right FPCN in frontal regions. Specifically, control subjects with high CR had significantly higher functional connectivity (FC) in frontal regions than control subjects with low CR, whereas this relation was inverted in WMH subjects. Correlative analyses showed positive associations of the FC with cognitive performance in both WMH subjects and control subjects, although the associations were not significant after correction for multiple comparisons. In conclusion, CR differentially regulated the FPCN in frontal regions between subjects with WMH and those without WMH. This regulation supports the flexibility of CR in regulating brain function and may underlie the effects of CR on cognitive function in WMH subjects.

Discrepancy Between Cognitive Test and Brain Imaging Results in Alzheimer's Disease Associated with Diabetes.

Although a large number of studies have been performed on the association between Alzheimer's disease (AD) and type 2 diabetes mellitus (DM), the underlying pathophysiology of AD associated with DM has not been fully elucidated to date. We compared cognitive functions and brain imaging findings between AD patients with and without DM to characterize the association between cognition and imaging findings in AD patients with DM. Cognitive functions and brain imaging findings, including medial temporal lobe atrophy analyzed by magnetic resonance imaging, and hypoperfusion in the parietal, posterior cingulate, and frontal regions analyzed by single-photon emission computed tomography were compared between 126 AD patients without DM ([AD-DM]) and 51 AD patients with DM ([AD+DM]). Factors associated with cognitive-imaging associations, including education, occupation, leisure activity, comorbidity, frailty, and other demographics, were analyzed. The [AD+DM] group showed significantly more severe cognitive dysfunction than the [ADDM] group, despite a similar degree of brain imaging abnormalities. Among the factors associated with cognitive-imaging associations, the level of leisure activity was significantly lower in the [AD+DM] group than in the [AD-DM] group, but no significant differences in other factors were observed between the 2 groups. The cognitive-imaging discrepancy observed in AD patients with DM may be associated with their low cognitive reserve, possibly caused by their low amount of leisure activities. Our findings suggest that lifestyle interventions, including physical, cognitive, and social activities, may reduce cognitive decline in AD patients with DM.