Education and occupation provide reserve in both ApoE ε4 carrier and noncarrier patients with probable Alzheimer's disease

Does Employment Complexity Promote Healthy Cognitive Aging in Down Syndrome?

Adults with Down syndrome (DS) experience high risk for Alzheimer's disease (AD), but there is variability in the timing of transition from a cognitively stable state to prodromal AD and dementia. The present study examined the association between a modifiable lifestyle factor, employment complexity, and cognitive decline across two time points in adults with DS. Employment complexity, defined as the degree of problem-solving or critical thinking required for employment activities, was operationalized using the Dictionary of Occupational Titles, a system which classifies occupations based on three categories: Data, People, and Things. Eighty-seven adults with DS (M = 36.28 years, SD = 6.90 years) were included in analyses. Partial correlations revealed that lower employment complexity involving People and Things were associated with increased dementia symptoms. Lower employment complexity involving Things was also associated with memory decline. These findings have implications for vocational programs focused on job training and placement for adults with DS.

Executive function deficits and medial temporal lobe atrophy in late-life depression and Alzheimer's disease: a comparative study

Objectives

Alzheimer's disease (AD) and late-life depression (LLD) frequently exhibit executive function deficits (EFD) and medial temporal lobe atrophy (MTA) as shared characteristics. The objective of this research was to examine the utility of the Trail Making Test (TMT) and the MTA scale in distinguishing between LLD and AD.

Methods

A study of 100 patients, 50 with AD and 50 with LLD, was conducted using a cross-sectional design. The individuals were subjected to clinical evaluations to assess their level of depression and overall cognitive abilities, which included the Geriatric Depression Scale (GDS), Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA). We evaluated executive function deficits (EFD) through the use of the TMT, which includes both TMT-A and TMT-B. MTA was measured using magnetic resonance imaging. To evaluate the ability of TMT and MTA scale to distinguish between the two groups, a receiver operating characteristic (ROC) curve was utilized. To investigate the connections between MTA and neuropsychological measures, a correlation analysis was performed.

Results

AD patients exhibited notably reduced MMSE, MoCA, and GDS scores, as well as an increased MTA total scores, time spent on TMT-A, and TMT-B compared to LLD patients (p < 0.05). TMT-A and TMT-B both exhibited excellent discriminatory power between AD and LLD, achieving area under curve (AUC) values of 92.2 and 94.2%, respectively. In AD patients, there was a negative correlation between MMSE and MoCA scores and MTA scores, while in LLD patients, there was a positive correlation between time spent on TMT-A and GDS scores and MTA scores.

Conclusion

AD patients experience more severe EFD and MTA than LLD patients. The differential diagnosis of AD and LLD can be aided by the useful tool known as TMT. It is important to acknowledge that TMT is capable of capturing only a fraction of the executive function, thus necessitating a cautious interpretation of research findings.

Turning Back the Clock: A Retrospective Single-Blind Study on Brain Age Change in Response to Nutraceuticals Supplementation vs. Lifestyle Modifications

BACKGROUND

There is a growing consensus that chronological age (CA) is not an accurate indicator of the aging process and that biological age (BA) instead is a better measure of an individual's risk of age-related outcomes and a more accurate predictor of mortality than actual CA. In this context, BA measures the "true" age, which is an integrated result of an individual's level of damage accumulation across all levels of biological organization, along with preserved resources. The BA is plastic and depends upon epigenetics. Brain state is an important factor contributing to health- and lifespan.

METHODS AND OBJECTIVE

Quantitative electroencephalography (qEEG)-derived brain BA (BBA) is a suitable and promising measure of brain aging. In the present study, we aimed to show that BBA can be decelerated or even reversed in humans (N = 89) by using customized programs of nutraceutical compounds or lifestyle changes (mean duration = 13 months).

RESULTS

We observed that BBA was younger than CA in both groups at the end of the intervention. Furthermore, the BBA of the participants in the nutraceuticals group was 2.83 years younger at the endpoint of the intervention compared with their BBA score at the beginning of the intervention, while the BBA of the participants in the lifestyle group was only 0.02 years younger at the end of the intervention. These results were accompanied by improvements in mental-physical health comorbidities in both groups. The pre-intervention BBA score and the sex of the participants were considered confounding factors and analyzed separately.

CONCLUSIONS

Overall, the obtained results support the feasibility of the goal of this study and also provide the first robust evidence that halting and reversal of brain aging are possible in humans within a reasonable (practical) timeframe of approximately one year.

Quantifying and Examining Reserve in Symptomatic Former National Football League Players

BACKGROUND

Repetitive head impacts (RHI) from contact sports have been associated with cognitive and neuropsychiatric disorders. However, not all individuals exposed to RHI develop such disorders. This may be explained by the reserve hypothesis. It remains unclear if the reserve hypothesis accounts for the heterogenous symptom presentation in RHI-exposed individuals. Moreover, optimal measurement of reserve in this population is unclear and likely unique from non-athlete populations.

OBJECTIVE

We examined the association between metrics of reserve and cognitive and neuropsychiatric functioning in 89 symptomatic former National Football League players.

METHODS

Individual-level proxies (e.g., education) defined reserve. We additionally quantified reserve as remaining residual variance in 1) episodic memory and 2) executive functioning performance, after accounting for demographics and brain pathology. Associations between reserve metrics and cognitive and neuropsychiatric functioning were examined.

RESULTS

Higher reading ability was associated with better attention/information processing (β=0.25; 95% CI, 0.05-0.46), episodic memory (β=0.27; 95% CI, 0.06-0.48), semantic and phonemic fluency (β=0.24; 95% CI, 0.02-0.46; β=0.38; 95% CI, 0.17-0.59), and behavioral regulation (β=-0.26; 95% CI, -0.48, -0.03) performance. There were no effects for other individual-level proxies. Residual episodic memory variance was associated with better attention/information processing (β=0.45; 95% CI, 0.25, 0.65), executive functioning (β=0.36; 95% CI, 0.15, 0.57), and semantic fluency (β=0.38; 95% CI, 0.17, 0.59) performance. Residual executive functioning variance was associated with better attention/information processing (β=0.44; 95% CI, 0.24, 0.64) and episodic memory (β=0.37; 95% CI, 0.16, 0.58) performance.

CONCLUSION

Traditional reserve proxies (e.g., years of education, occupational attainment) have limitations and may be unsuitable for use in elite athlete samples. Alternative approaches of reserve quantification may prove more suitable for this population.

Non-mental diseases associated with ADHD across the lifespan: Fidgety Philipp and Pippi Longstocking at risk of multimorbidity?

Several non-mental diseases seem to be associated with an increased risk of ADHD and ADHD seems to be associated with increased risk for non-mental diseases. The underlying trajectories leading to such brain-body co-occurrences are often unclear - are there direct causal relationships from one disorder to the other, or does the sharing of genetic and/or environmental risk factors lead to their occurring together more frequently or both? Our goal with this narrative review was to provide a conceptual synthesis of the associations between ADHD and non-mental disease across the lifespan. We discuss potential shared pathologic mechanisms, genetic background and treatments in co-occurring diseases. For those co-occurrences for which published studies with sufficient sample sizes exist, meta-analyses have been published by others and we discuss those in detail. We conclude that non-mental diseases are common in ADHD and vice versa and add to the disease burden of the patient across the lifespan. Insufficient attention to such co-occurring conditions may result in missed diagnoses and suboptimal treatment in the affected individuals.

Effects of APOE e4-allele and mental work demands on cognitive decline in old age: Results from the German Study on Ageing, Cognition, and Dementia in Primary Care Patients (AgeCoDe)

OBJECTIVES

Previous studies have observed protective effects of high mental demands at work on cognitive functioning and dementia risk. However, it is unclear what types of demands drive this effect and whether this effect is subject to a person's genetic risk. We investigated to what extent eight different types of mental demands at work together with the APOE e4 allele, a major risk gene for late-onset Alzheimer's disease, affect cognitive functioning in late life.

METHODS/DESIGN

The population-based German Study on Ageing, Cognition, and Dementia in Primary Care Patients (AgeCoDe, n = 2 154) followed cognitively healthy individuals aged 75 years and older in seven assessment waves. Cognitive functioning was assessed via the mini-mental status examination.

RESULTS

Mixed-effects modeling (adjusted for education, gender, marital status, stroke, depression, and diabetes) indicated that participants who had an occupational history of working in jobs with high compared to low demands in "Language & Knowledge", "Pattern detection", "Information processing", and "Service" had a slower cognitive decline. APOE e4-allele carriers had an accelerated cognitive decline, but this decline was significantly smaller if they had a medium compared to a low level of demands in contrast to non-carriers.

CONCLUSIONS

Our longitudinal observations suggest that cognitive decline could be slowed by an intellectually enriched lifestyle even in risk gene carriers. Fostering intellectual engagement throughout the life-course could be a key prevention initiative to promote better cognitive health in old age.

The interplay among education, brain metabolism, and cognitive impairment suggests a role of cognitive reserve in Amyotrophic Lateral Sclerosis

We tested the Cognitive Reserve (CR) hypothesis in Amyotrophic Lateral Sclerosis (ALS), enrolling 111 patients, using education as CR proxy, ¹⁸F-FDG-PET to assess brain damage, and ECAS to measure cognition. Education was regressed out against brain metabolism, including age, sex, spinal/bulbar onset, ALSFRS-R, and ECAS as covariates. Clusters showing a significant correlation were used as seed regions in an interregional correlation analysis (IRCA) in the ALS group and in 40 controls. In the ALS group, we found a negative correlation between brain metabolism and education in the right anterior cingulate and bilateral medial frontal gyrus. In the IRCA in the ALS group, the medial frontal cluster metabolism positively correlated with that of frontotemporal regions (right > left), bilateral caudate nuclei, and right insula, and negatively correlated with that of corticospinal tracts, cerebellum, and pons. In controls, the IRCA showed significant positive correlations in the same regions but less extended. Our results agree with the CR hypothesis. The negative correlation between the medial frontal cluster and the cerebellum found only in ALS patients might reflect cerebellar compensation.

Occupational Patterns of Structural Brain Health: Independent Contributions Beyond Education, Gender, Intelligence, and Age

Occupational activity represents a large percentage of people's daily activity and thus likely is as impactful for people's general and cognitive health as other lifestyle components such as leisure activity, sleep, diet, and exercise. Different occupations, however, require different skills, abilities, activities, credentials, work styles, etc., constituting a rich multidimensional formative exposure with likely consequences for brain development over the lifespan. In the current study, we were interested in how different occupations with their different attributes relate to five variables: structural brain health, duration of early-life education, gender, IQ, and age, although the main focus was the relationship to brain health. To this end, we used the Occupation Information Network (O∗NET), which provides quantification of occupations along 246 items. Occupational patterns with different loadings for these 246 items were derived from 277 community-dwelling adults, ranging in age from 40 to 80, based upon the five subject measures. We found significant patterns underlying four of our variables of interest, with gender and education predictably showing the most numerous and strongest associations, while brain health and intelligence showed weaker associations, and age did not manifest any associations. For the occupational pattern associated with brain health, we found mainly positive associations on items pertaining to rigorous problem-solving, leadership, responsibility, and information processing. We emphasize that the findings are correlational and cannot establish causation. Future extensions of this work will assess the influence of occupation on future cognitive brain status and cognitive performance.

The Role of Cognitive Reserve in Alzheimer's Disease and Aging: A Multi-Modal Imaging Review

Comforts in modern society have generally been associated with longer survival rates, enabling individuals to reach advanced age as never before in history. With the increase in longevity, however, the incidence of neurodegenerative diseases, especially Alzheimer's disease, has also doubled. Nevertheless, most of the observed variance, in terms of time of clinical diagnosis and progression, often remains striking. Only recently, differences in the social, educational and occupational background of the individual, as proxies of cognitive reserve (CR), have been hypothesized to play a role in accounting for such discrepancies. CR is a well-established concept in literature; lots of studies have been conducted in trying to better understand its underlying neural substrates and associated biomarkers, resulting in an incredible amount of data being produced. Here, we aimed to summarize recent relevant published work addressing the issue, gathering evidence for the existence of a common path across research efforts that might ease future investigations by providing a general perspective on the actual state of the arts. An innovative model is hereby proposed, addressing the role of CR across structural and functional evidences, as well as the potential implementation of non-invasive brain stimulation techniques in the causal validation of such theoretical frame.

Rethinking the Reserve with a Translational Approach: Novel Ideas on the Construct and the Interventions

The concept of brain, cognitive, and neural reserves has been introduced to account for the apparent discrepancies between neurological damage and clinical manifestations. However, these ideas are yet theoretical suggestions that are not completely assimilated in the clinical routine. The mechanisms of the reserves have been extensively studied in neurodegenerative pathologies, in particular in Alzheimer's disease. Both human and animal studies addressed this topic by following two parallel pathways. The specific aim of the present review is to attempt to combine the suggestions derived from the two different research fields to deepen the knowledge about reserves. In fact, the achievement of a comprehensive theoretical framework on reserve mechanisms is an essential step to propose well-timed interventions tailored to the clinical characteristics of patients. The present review highlights the importance of addressing three main aspects: the definition of reserve proxy measures, the interaction between reserve level and therapeutic interventions, and the specific time-window of reserve efficacy.

Activation of the Brain to Postpone Dementia: A Concept Originating from Postmortem Human Brain Studies

Alzheimer's disease (AD) is characterized by decreased neuronal activity and atrophy, while hyperactivity of neurons seems to make them resistant to aging and neurodegeneration, a phenomenon which we have paraphrased as 'use it or lose it'. Our hypothesis proposes that (1) during their functioning, neurons are damaged; (2) accumulation of damage that is not repaired is the basis of aging; (3) the vulnerability to AD is determined by the genetic background and the balance between the amount of damage and the efficiency of repair, and (4) by stimulating the brain, repair mechanisms are stimulated and cognitive reserve is increased, resulting in a decreased rate of aging and risk for AD. Environmental stimulating factors such as bilingualism/multilingualism, education, occupation, musical experience, physical exercise, and leisure activities have been reported to reduce the risk of dementia and decrease the rate of cognitive decline, although methodological problems are present.

The dual role of cognitive reserve in subjective cognitive decline and mild cognitive impairment: a 7-year follow-up study

The aim of this study was to evaluate the effect of cognitive reserve (CR), in progression from subjective cognitive decline (SCD) to mild cognitive impairment (MCI) and Alzheimer's disease (AD). For this purpose, we followed up 263 patients (154 SCD; 109 MCI) for a mean time of 7 years. CR was assessed by the Test di Intelligenza Breve (TIB), functionally equivalent to the National Adult Reading Test. High CR resulted as a protective factor for progression from SCD to MCI. Age at conversion to MCI was delayed 9 years on average in SCD with high CR with respect to SCD with low CR. On the contrary, high CR resulted as a risk factor for progression from MCI to AD dementia only in APOE ε4 carriers. Conversion time from MCI to AD dementia was 3 years shorter in ε4 carriers with high CR than subjects with low CR and ε4 non-carriers with high CR. Consistent with the CR hypothesis, our results showed that higher levels of CR protect against the earliest clinical manifestations of AD. In line with the previous researches, we found an interaction between CR and APOE in progression from MCI to AD dementia.

A Brief Review of Paradigm Shifts in Prevention of Alzheimer's Disease: From Cognitive Reserve to Precision Medicine

Alzheimer's disease (AD) and related dementias can be an enormous economic burden for taxpayers, patients, their families, medical systems, and society as a whole. Since disease-modifying treatments have failed, several studies have instead focused on a paradigm shift for preventing and treating AD. A higher cognitive reserve (e.g., greater education, occupational attainment, or more leisure activities) is associated with protection against disease-related cognitive decline. Precision medicine aims to optimize the effectiveness of disease prevention and treatment by considering specific biological components of individuals. We suggest that research into cognitive reserve and precision medicine could be a key to overcoming the limitations of traditional approaches to the prevention and treatment of AD.

Life-course determinants of cognitive reserve (CR) in cognitive aging and dementia - a systematic literature review

OBJECTIVES

The concept of cognitive reserve (CR) is defined as a moderator, which allows an individual to preserve cognition despite underlying brain pathology. There is no consensus of what potentially modifiable CR determinants are of greatest importance. The aim of this review was to identify life-course factors which protect older individuals from expressing cognitive decline despite the presence of brain pathology.

METHOD

A systematic review search was performed in MEDLINE (1946-06/09/13), EMBASE (1947-06/09/13), and PsycheInfo (1967-06/09/13). We included studies examining CR in the context of the four commonest subtypes of dementia, mild cognitive impairment or healthy aging. Studies which combined measurement of underlying dementia-related neuropathology, cognitive function, and factors providing CR in a single model were accepted. We performed a qualitative synthesis of the results.

RESULTS

Thirty-four studies out of 9229 screened records met our inclusion criteria and were therefore quality assessed and data extracted. Variation in CR definition made comparison across studies difficult. One hundred and forty-four out of 156 models examined education and occupation: overall, 58% of eligible models classified education and 60% occupation as a CR determinant, with 12% and 44% of those, respectively, being of high quality. Within healthy population suitable to inform preventative interventions, there was consistent evidence for education having a protective effect on general cognition in the face of multiple brain burden measures, while occupation presented inconclusive results within cognitive groups.

CONCLUSIONS

Further research on modifiable determinants of CR beyond education/occupation including early-life factors and consensus on CR definition are warranted.

Cognitive Reserve and Brain Maintenance: Orthogonal Concepts in Theory and Practice

Cognitive Reserve and Brain Maintenance have traditionally been understood as complementary concepts: Brain Maintenance captures the processes underlying the structural preservation of the brain with age, and might be assessed relative to age-matched peers. Cognitive Reserve, on the other hand, refers to how cognitive processing can be performed regardless of how well brain structure has been maintained. Thus, Brain Maintenance concerns the "hardware," whereas Cognitive Reserve concerns "software," that is, brain functioning explained by factors beyond mere brain structure. We used structural brain data from 368 community-dwelling adults, age 20-80, to derive measures of Brain Maintenance and Cognitive Reserve. We found that Brain Maintenance and Cognitive were uncorrelated such that values on one measure did not imply anything about the other measure. Further, both measures were positively correlated with verbal intelligence and education, hinting at formative influences of the latter to both measures. We performed extensive split-half simulations to check our derived measures' statistical robustness. Our approach enables the out-of-sample quantification of Brain Maintenance and Cognitive Reserve for single subjects on the basis of chronological age, neuropsychological performance and structural brain measures. Future work will investigate the prognostic power of these measures with regard to future cognitive status.

Simultaneous quantitative susceptibility mapping and Flutemetamol-PET suggests local correlation of iron and β-amyloid as an indicator of cognitive performance at high age

The accumulation of β-amyloid plaques is a hallmark of Alzheimer's disease (AD), and recently published data suggest that increased brain iron burden may reflect pathologies that synergistically contribute to the development of cognitive dysfunction. While preclinical disease stages are considered most promising for therapeutic intervention, the link between emerging AD-pathology and earliest clinical symptoms remains largely unclear. In the current study we therefore investigated local correlations between iron and β-amyloid plaques, and their possible association with cognitive performance in healthy older adults. 116 older adults (mean age 75 ± 7.4 years) received neuropsychological testing to calculate a composite cognitive score of performance in episodic memory, executive functioning, attention, language and communication. All participants were scanned on a combined PET-MRI instrument and were administered T1-sequences for anatomical mapping, quantitative susceptibility mapping (QSM) for assessing iron, and 18F-Flutemetamol-PET for estimating β-amyloid plaque load. Biological parametric mapping (BPM) was used to generate masks indicating voxels with significant (p < 0.05) correlation between susceptibility and 18F-Flutemetamol-SUVR. We found a bilateral pattern of clusters characterized by a statistical relationship between magnetic susceptibility and 18F-Flutemetamol-SUVR, indicating local correlations between iron and β-amyloid plaque deposition. For two bilateral clusters, located in the frontal and temporal cortex, significant relationships (p<0.05) between local β-amyloid and the composite cognitive performance score could be observed. No relationship between whole-cortex β-amyloid plaque load and cognitive performance was observable. Our data suggest that the local correlation of β-amyloid plaque load and iron deposition may provide relevant information regarding cognitive performance of healthy older adults. Further studies are needed to clarify pathological correlates of the local interaction of β-amyloid, iron and other causes of altered magnetic susceptibility.

Occupational Attainment as Risk Factor for Progression from Mild Cognitive Impairment to Alzheimer's Disease: A CREDOS Study

High occupational attainment has been known as a marker of cognitive reserve. Previous studies in the general population have shown that high occupational attainment is associated with reduced risk of Alzheimer's disease (AD). However, few studies have assessed the effect of occupational attainment on the clinical course of mild cognitive impairment (MCI). In this study, we evaluated whether individuals with high occupational attainment show more frequent progression from MCI to AD. Participants (n = 961) with MCI were recruited from a nationwide, hospital-based multi-center cohort, and were followed for up to 60 months (median: 17.64, interquartile range [12.36, 29.28]). We used Cox regression for competing risks to analyze the effect of occupational attainment on development of AD, treating dementia other than AD as a competing risk. Among the 961 individuals with MCI, a total of 280 (29.1%) converted to dementia during the follow-up period. The risk of progression to AD was higher in the individuals with high occupational attainment after controlling for potential confounders (hazard ratio = 1.83, 95% confidence interval = 1.25-2.69, p = 0.002). High occupational attainment in individuals with MCI is an independent risk factor for higher progression rate of MCI to AD. This result suggests that the protective effect of high occupational attainment against cognitive decline disappears in the MCI stage, and that careful assessment of occupational history can yield important clinical information for prognosis in individuals with MCI.

Low cortical iron and high entorhinal cortex volume promote cognitive functioning in the oldest-old

The aging brain is characterized by an increased presence of neurodegenerative and vascular pathologies. However, there is substantial variation regarding the relationship between an individual's pathological burden and resulting cognitive impairment. To identify correlates of preserved cognitive functioning at highest age, the relationship between β-amyloid plaque load, presence of small vessel cerebrovascular disease (SVCD), iron-burden, and brain atrophy was investigated. Eighty cognitively unimpaired participants (44 oldest-old, aged 85-96 years; 36 younger-old, aged 55-80 years) were scanned by integrated positron emission tomography-magnetic resonance imaging for assessing beta regional amyloid plaque load (18F-flutemetamol), white matter hyperintensities as an indicator of SVCD (fluid-attenuated inversion recovery-magnetic resonance imaging), and iron load (quantitative susceptibility mapping). For the oldest-old group, lower cortical volume, increased β-amyloid plaque load, prevalence of SVCD, and lower cognitive performance in the normal range were found. However, compared to normal-old, cortical iron burden was lower in the oldest-old. Moreover, only in the oldest-old, entorhinal cortex volume positively correlated with β-amyloid plaque load. Our data thus indicate that the co-occurrence of aging-associated neuropathologies with reduced quantitative susceptibility mapping measures of cortical iron load constitutes a lower vulnerability to cognitive loss.

The effects of apolipoprotein E genotype, α-synuclein deficiency, and sex on brain synaptic and Alzheimer's disease-related pathology

Introduction

Alzheimer's disease (AD) and synucleinopathies share common pathological mechanisms. Apolipoprotein E4 (apoE4), the most prevalent genetic risk factor for AD, also increases the risk for dementia in pure synucleinopathies. We presently examined the effects of α-synuclein deficiency (α-syn−/−) and sex on apoE4-driven pathologies.

Methods

AD-related, synaptic, and vascular markers were analyzed in female and male α-syn−/− and α-syn+/+ apoE4, apoE3, and apoE3/E4 mice.

Results

ApoE4 was hypolipidated, and this effect was unchanged by α-syn−/− and sex. The levels of synaptic markers were lower, and the levels of AD-related parameters were higher in female α-syn−/− apoE4 mice compared with the corresponding apoE3 mice. By comparison, apoE4 had small effects on the AD parameters of male and female α-syn+/+ apoE4 mice.

Discussion

Although α-syn−/− does not affect the upstream lipidation impairment of apoE4, it acts as a “second hit” enhancer of the subsequent apoE4-driven pathologies.

Cardiovascular Pharmacogenomics and Cognitive Function in Patients with Schizophrenia

The authors sought to examine the impact of multiple risk alleles for cognitive dysfunction and cardiovascular disease risk on cognitive function and to determine if these relationships varied by cognitive reserve (CR) or concomitant medication use in patients with schizophrenia. They conducted a cross-sectional study in ambulatory mental health centers. A total of 122 adults with a schizophrenia spectrum diagnosis who were maintained on a stable antipsychotic regimen for at least 6 months before study enrollment were included. Patients were divided into three CR groups based on years of formal education: no high school completion or equivalent (low-education group [18 patients]), completion of high school or equivalent (moderate-education group [36 patients], or any degree of post-high school education (high-education group [68 patients]). The following pharmacogenomic variants were genotyped for each patient: AGT M268T (rs699), ACE insertion/deletion (or ACE I/D, rs1799752), and APOE ε2, ε3, and ε4 (rs429358 and rs7412). Risk allele carrier status (identified per gene as AGT M268 T carriers, ACE D carriers, and APOE ε4 carriers) was not significantly different among CR groups. The Brief Assessment of Cognition in Schizophrenia (BACS) scale was used to assess cognitive function. The mean ± SD patient age was 43.9 ± 11.6 years. Cardiovascular risk factors such as hypertension and hyperlipidemia diagnoses, and use of antihypertensive and lipid-lowering agents, did not significantly differ among CR groups. Mixed modeling revealed that risk allele carrier status was significantly associated with lower verbal memory scores for ACE D and APOE ε4 carriers, but AGT T carrier status was significantly associated with higher verbal memory scores (p=0.0188, p=0.0055, and p=0.0058, respectively). These results were only significant in the low-education group. In addition, medication-gene interactions were not significant predictors of BACS scores. ACE D and APOE ε4 carrier status, independent of medication use, was associated with lower verbal memory scores in patients with schizophrenia who had relatively lower CR, as identified by formal education. These results suggest that increasing CR may be protective against cognitive impairment that may be worsened by select cardiovascular risk alleles in patients with schizophrenia.

Searching for Primary Predictors of Conversion from Mild Cognitive Impairment to Alzheimer's Disease: A Multivariate Follow-Up Study

Recent proposals of diagnostic criteria within the healthy aging-Alzheimer's disease (AD) continuum stressed the role of biomarker information. More importantly, such information might be critical to predict those mild cognitive impairment (MCI) patients at a higher risk of conversion to AD. Usually, follow-up studies utilize a reduced number of potential markers although the conversion phenomenon may be deemed as multifactorial in essence. In addition, not only biological but also cognitive markers may play an important role. Considering this background, we investigated the role of cognitive reserve, cognitive performance in neuropsychological testing, hippocampal volumes, APOE genotype, and magnetoencephalography power sources to predict the conversion to AD in a sample of 33 MCI patients. MCIs were followed up during a 2-year period and divided into two subgroups according to their outcome: The "stable" MCI group (sMCI, 21 subjects) and the "progressive" MCI group (pMCI, 12 subjects). Baseline multifactorial information was submitted to a hierarchical logistic regression analysis to build a predictive model of conversion to AD. Results indicated that the combination of left hippocampal volume, occipital cortex theta power, and clock drawing copy subtest scores predicted conversion to AD with a 100% of sensitivity and 94.7% of specificity. According to these results it might be suggested that anatomical, cognitive, and neurophysiological markers may be considered as "first order" predictors of progression to AD, while APOE or cognitive reserve proxies might play a more secondary role.

Association between DCHS2 gene and mild cognitive impairment and Alzheimer's disease in an elderly Brazilian sample

OBJECTIVES

In 2012, Kamboh and colleagues published a genome-wide association study that identified the DCHS2 gene (rs1466662 T/A) influencing the age at onset of Alzheimer's disease (AD). We aimed to investigate if there is association between the DCHS2 gene and amnestic mild cognitive impairment (aMCI) and AD in a sample of the Brazilian population.

METHODS

143 controls, 79 aMCI and 299 AD patients were selected and submitted to the same protocol of tests. Genotyping was performed using the Real Time PCR RESULTS: Amnestic MCI patients showed a higher prevalence of AA than controls and a lower frequency of TT when compared with controls. We also stratified the sample according to the APOE ε4 status. No difference in DCHS2 genotype or allelic frequency occurred in the APOE ε4 allele carrier subgroup. Amnestic MCI patients showed a higher frequency of AA genotype and a lower frequency of TA and TT when compared with controls in APOE ε4 allele non-carrier subgroup. The allelic distribution followed the same pattern. In AD group, we observed a significant difference with a higher A allelic frequency in AD in this subgroup. A multiple logistic regression demonstrated that in APOE ε4 non-carriers, allele rs1466662 was associated to aMCI group. Different variables were associated with aMCI and AD according to APOE ε4 status in our sample. Low level of education was associated with AD, while diabetes mellitus type 2 was associated with aMCI. Copyright © 2016 John Wiley & Sons, Ltd.

CONCLUSIONS

Our findings suggest a possible role for DCHS2 gene in aMCI and AD.

Education is associated with sub-regions of the hippocampus and the amygdala vulnerable to neuropathologies of Alzheimer's disease

We evaluated the correlation of educational attainment with structural volume and shape morphometry of the bilateral hippocampi and amygdalae in a sample of 110 non-demented, older adults at elevated sociodemographic risk for cognitive and functional declines. In both men and women, no significant education-volume correlation was detected for either structure. However, when performing shape analysis, we observed regionally specific associations with education after adjusting for age, intracranial volume, and race. By sub-dividing the hippocampus and the amygdala into compatible subregions, we found that education was positively associated with size variations in the CA1 and subiculum subregions of the hippocampus and the basolateral subregion of the amygdala (p < 0.05). In addition, we detected a greater left versus right asymmetric pattern in the shape-education correlation for the hippocampus but not the amygdala. This asymmetric association was largely observed in men versus women. These findings suggest that education in youth may exert direct and indirect influences on brain reserve in regions that are most vulnerable to the neuropathologies of aging, dementia, and specifically, Alzheimer disease.

Large intracranial volume accelerates conversion to dementia in males and APOE4 non-carriers with mild cognitive impairment

BACKGROUND

It is unclear how brain reserve interacts with gender and apolipoprotein E4 (APOE4) genotype, and how this influences the progression of Alzheimer's disease (AD). The association between intracranial volume (ICV) and progression to AD in subjects with mild cognitive impairment (MCI), and differences according to gender and APOE4 genotype, was investigated.

METHODS

Data from subjects initially diagnosed with MCI and at least two visits were downloaded from the ADNI database. Those who progressed to AD were defined as converters. The longitudinal influence of ICV was determined by survival analysis. The time of conversion from MCI to AD was set as a fiducial point, as all converters would be at a similar disease stage then, and longitudinal trajectories of brain atrophy and cognitive decline around that point were compared using linear mixed models.

RESULTS

Large ICV increased the risk of conversion to AD in males (HR: 4.24, 95% confidence interval (CI): 1.17-15.40) and APOE4 non-carriers (HR: 10.00, 95% CI: 1.34-74.53), but not in females or APOE4 carriers. Cognitive decline and brain atrophy progressed at a faster rate in males with large ICV than in those with small ICV during the two years before and after the time of conversion.

CONCLUSIONS

Large ICV increased the risk of conversion to AD in males and APOE4 non-carriers with MCI. This may be due to its influence on disease trajectory, which shortens the duration of the MCI stage. A longitudinal model of progression trajectory is proposed.

Influence of Formal Education on Cognitive Reserve in Patients with Multiple Sclerosis

The concept of cognitive reserve (CR) and its influence on cognitive impairment has attracted increasing interest. One hundred twenty-eight patients with multiple sclerosis (MS) from Southern Germany were evaluated during the years 2000 to 2012. Twenty-seven neuropsychological (NP) tests were applied regarding basic cognitive functions, attention, executive functions, visual perception and construction, memory and learning, problem solving, and language. By this retrospective approach, a comprehensive NP profile of the investigated individuals was established. An effect of timespan of formal education on CR was observed. Enrichment by reading, physical activities, and challenging vocational practices had more profound effects in patients who had undergone a shorter educational period compared to a longer educational period. In summary, our study demonstrates that the advantage of longer formal education periods, compared to shorter formal education periods, can be counterbalanced by high frequencies of reading, physical activities, and challenging vocational practices in patients with MS.

The GAB2 and BDNF polymorphisms and the risk for late-onset Alzheimer's disease in an elderly Brazilian sample

BACKGROUND

Evidences suggest that GAB2 and BDNF genes may be associated with Alzheimer's disease (AD). We aimed to investigate the GAB2 rs2373115 and BDNF rs6265 polymorphisms and the risk of AD in a Brazilian sample.

METHODS

269 AD patients and 114 controls were genotyped with Real-time PCR. Multifactor dimensionality reduction (MDR) was employed to explore the effects of gene-gene interactions.

RESULTS

GAB2 and BDNF were not associated with AD in our sample. Nevertheless BDNF Val allele (rs6265) presented a synergic association with the APOE ε4 allele. A multiple logistic regression demonstrated that the APOE ε4 allele and years of education were the best predictors for AD. In ε4 non-carriers sex, education and hypertension were independently correlated with AD, while in ε4 carriers we did not observe any association. The findings were further confirmed by bootstrapping method.

CONCLUSIONS

Our data suggest that the interaction of BDNF and APOE has significant effect on AD. Moreover in absence of ε4, female sex, low level of education and hypertension are independently associated with AD. Interventions aimed to prevent AD should focus on these factors and also taking into account the APOE alleles.

Prevalence of Dementia and Cognitive Complaints in the Context of High Cognitive Reserve: A Population-Based Study

OBJECTIVES

This study aimed to assess the prevalence of dementia and cognitive complaints in a cross-sectional sample of Luxembourg seniors, and to discuss the results in the societal context of high cognitive reserve resulting from multilingualism.

METHODS

A population sample of 1,377 people representative of Luxembourg residents aged over 64 years was initially identified via the national social insurance register. There were three different levels of contribution: full participation in the study, partial participation, and non-participation. We examined the profiles of these three different samples so that we could infer the prevalence estimates in the Luxembourgish senior population as a whole using the prevalence estimates obtained in this study.

RESULTS

After careful attention to the potential bias and of the possibility of underestimation, we considered the obtained prevalence estimates of 3.8% for dementia (with corresponding 95% confidence limits (CL) of 2.8% and 4.8%) and 26.1% for cognitive complaints (CL = [17.8-34.3]) as trustworthy.

CONCLUSION

Based on these findings, we postulate that high cognitive reserve may result in surprisingly low prevalence estimates of cognitive complaints and dementia in adults over the age of 64 years, which thereby corroborates the longer disability-free life expectancy observed in the Luxembourg population. To the best of our knowledge, this study is the first to report such Luxembourgish public health data.

Occupational Complexity and Cognitive Reserve in a Middle-Aged Cohort at Risk for Alzheimer's Disease

Higher occupational attainment has previously been associated with increased Alzheimer's disease (AD) neuropathology when individuals are matched for cognitive function, indicating occupation could provide cognitive reserve. We examined whether occupational complexity (OCC) associates with decreased hippocampal volume and increased whole-brain atrophy given comparable cognitive function in middle-aged adults at risk for AD. Participants (n = 323) underwent structural MRI, cognitive evaluation, and work history assessment. Three complexity ratings (work with data, people, and things) were obtained, averaged across up to 3 reported jobs, weighted by years per job, and summed to create a composite OCC rating. Greater OCC was associated with decreased hippocampal volume and increased whole-brain atrophy when matched for cognitive function; results remained substantively unchanged after adjusting for several demographic, AD risk, vascular, mental health, and socioeconomic characteristics. These findings suggest that, in people at risk for AD, OCC may confer resilience to the adverse effects of neuropathology on cognition.

Risk factors for age at onset of dementia due to Alzheimer's disease in a sample of patients with low mean schooling from São Paulo, Brazil

OBJECTIVE

In view of the mild effects of pharmacological treatment for dementia due to Alzheimer's disease (AD), the search for modifiable risk factors is an important challenge. Although risk factors for AD are widely recognized, elements that influence the time of onset of the dementia syndrome have not been comprehensively reported. We aimed to investigate which risk factors might be associated with the age at onset of AD in a sample of patients with low mean schooling from São Paulo, Brazil.

METHODS

We included 210 consecutive patients with late-onset AD to investigate whether education, gender, nationality, urban living and sanitation, occupation, cognitive and physical inactivity, head trauma, depression, systemic infections, surgical interventions, cerebrovascular risk factors, family history of neurodegenerative diseases or cardiovascular diseases and apolipoprotein E gene (APOE) haplotypes might be related to the age at AD onset.

RESULTS

Each copy of APOE-ε4 led to onset of AD almost 2 years earlier, while depression, smoking, higher body mass index and family history of cardiovascular diseases were also highly significant. Protective factors included non-Brazilian nationality, use of a pacemaker and waist circumference. Cerebrovascular risk factors had a mild combined effect for earlier onset of AD.

CONCLUSION

APOE haplotypes, depression, nationality and cerebrovascular risk factors were the most important elements to influence the age at AD onset in this sample, whereas gender, education, occupation and physical activities had no isolated effects over the age at onset of this dementia syndrome.

Cognitive reserve is associated with the functional organization of the brain in healthy aging: a MEG study

The proportion of elderly people in the population has increased rapidly in the last century and consequently “healthy aging” is expected to become a critical area of research in neuroscience. Evidence reveals how healthy aging depends on three main behavioral factors: social lifestyle, cognitive activity, and physical activity. In this study, we focused on the role of cognitive activity, concentrating specifically on educational and occupational attainment factors, which were considered two of the main pillars of cognitive reserve (CR). Twenty-one subjects with similar rates of social lifestyle, physical and cognitive activity were selected from a sample of 55 healthy adults. These subjects were divided into two groups according to their level of CR; one group comprised subjects with high CR (9 members) and the other one contained those with low CR (12 members). To evaluate the cortical brain connectivity network, all participants were recorded by Magnetoencephalography (MEG) while they performed a memory task (modified version of the Sternberg's Task). We then applied two algorithms [Phase Locking Value (PLV) and Phase Lag Index (PLI)] to study the dynamics of functional connectivity. In response to the same task, the subjects with lower CR presented higher functional connectivity than those with higher CR. These results may indicate that participants with low CR needed a greater “effort” than those with high CR to achieve the same level of cognitive performance. Therefore, we conclude that CR contributes to the modulation of the functional connectivity patterns of the aging brain.

Personality as a moderator of cognitive stimulation in older adults at high risk for cognitive decline

This exploratory study examined the moderating effects of personality traits on cognitive function following a cognitively stimulating individualized activity intervention delivered to individuals at high risk for cognitive decline: those with delirium superimposed on dementia. Data were taken from an ongoing randomized clinical trial with the addition of a personality measure. The results for 71 participants randomized to intervention or control groups are reported. Significant moderating effects of personality traits were found such that participants with higher agreeableness were more likely to have improved delayed recall and those with lower extraversion were more likely to have improved executive function, as a result of the intervention. Lower openness, higher agreeableness, and lower conscientiousness were associated with greater engagement in the intervention. A cognitive stimulation intervention for older adults at high risk for further cognitive decline may be differentially effective based on certain personality traits.

Prestroke dementia: characteristics and clinical features in consecutive series of patients

BACKGROUND/AIM

The prestroke level of cognitive function should be taken into account in order to predict the impact of stroke on the subsequent risk of dementia. The aim of the present study was to investigate the presence and correlates of prestroke dementia (PSD) as well as to identify its clinical features.

METHODS

Premorbid clinical and cognitive features of 158 consecutively recruited patients with a diagnosis of acute cerebrovascular pathology were assessed by interviewing the caregivers using multidimensional assessment. Patients were divided into two groups (PSD group and prestroke nondemented group). Baseline cognitive, functional and behavioral variables and neuroradiological hallmarks (medial temporal lobe atrophy, MTLA) were compared between these two groups.

RESULTS

In a logistic regression model, older age (OR 1.05), female gender (OR 2.3), Neuropsychiatric Inventory total score (OR 1.1) and MTLA (OR 1.2) were the variables independently associated with PSD.

CONCLUSIONS

These findings support the hypothesis that cognitive impairment in patients with stroke may not only be a direct consequence of the acute cerebrovascular event but also a consequence of underlying neurodegenerative pathology.

Cognitive reserve in granulin-related frontotemporal dementia: from preclinical to clinical stages

Objective

Consistent with the cognitive reserve hypothesis, higher education and occupation attainments may help persons with neurodegenerative dementias to better withstand neuropathology before developing cognitive impairment. We tested here the cognitive reserve hypothesis in patients with frontotemporal dementia (FTD), with or without pathogenetic granulin mutations (GRN+ and GRN-), and in presymptomatic GRN mutation carriers (aGRN+).

Methods

Education and occupation attainments were assessed and combined to define Reserve Index (RI) in 32 FTD patients, i.e. 12 GRN+ and 20 GRN-, and in 17 aGRN+. Changes in functional connectivity were estimated by resting state fMRI, focusing on the salience network (SN), executive network (EN) and bilateral frontoparietal networks (FPNs). Cognitive status was measured by FTD-modified Clinical Dementia Rating Scale.

Results

In FTD patients higher level of premorbid cognitive reserve was associated with reduced connectivity within the SN and the EN. EN was more involved in FTD patients without GRN mutations, while SN was more affected in GRN pathology. In aGRN+, cognitive reserve was associated with reduced SN.

Conclusions

This study suggests that cognitive reserve modulates functional connectivity in patients with FTD, even in monogenic disease. In GRN inherited FTD, cognitive reserve mechanisms operate even in presymptomatic to clinical stages.

Lifelong exposure to multilingualism: new evidence to support cognitive reserve hypothesis

Objective

Investigate the protective effect of multilingualism on cognition in seniors.

Methods

As part of the MemoVie study conducted on 232 non-demented volunteers aged 65 and more, neurogeriatric and neuropsychological evaluations were performed. Participants were classified as presenting either cognitive impairment without dementia (CIND) or being free of any cognitive impairment (CIND-free). Language practices, socio-demographic data and lifestyle habits were recorded. In this retrospective nested case-control design, we used as proxies of multilingualism: number of languages practiced, age of acquisition and duration of practice, emphasizing the temporal pattern of acquisition, and the resulting practice of several languages sequentially or concomitantly during various periods of life. This special angle on the matter offered to our work a dimension particularly original and innovative.

Results

44 subjects (19%) had CIND, the others were cognitively normal. All practiced from 2 to 7 languages. When compared with bilinguals, participants who practiced more than 2 languages presented a lower risk of CIND, after adjustment for education and age (odds ratio (OR) = 0.30, 95% confidence limits (95%CL) = [0.10–0.92]). Progressing from 2 to 3 languages, instead of staying bilingual, was associated with a 7-fold protection against CIND (OR = 0.14, 95%CL = [0.04–0.45], p = 0.0010). A one year delay to reach multilingualism (3 languages practiced being the threshold) multiplied the risk of CIND by 1.022 (OR = 1.022, 95%CL = [1.01–1.04], p = 0.0044). Also noteworthy, just as for multilingualism, an impact of cognitively stimulating activities on the occurrence of CIND was found as well (OR = 0.979, 95%CL = [0.961–0.998], p = 0.033).

Conclusion

The study did not show independence of multilingualism and CIND. Rather it seems to show a strong association toward a protection against CIND. Practicing multilingualism from early life on, and/or learning it at a fast pace is even more efficient. This protection might be related to the enhancement of cognitive reserve and brain plasticity, thereby preserving brain functions from alterations during aging.