Brain aging and Alzheimer's disease, "wear and tear" versus "use it or lose it"

A systematic review of epidemiological studies of life course socioeconomic status and adult structural brain changes

INTRODUCTION

Disadvantaged socioeconomic status (SES) are linked with adverse cognitive outcomes in ageing and heightened dementia risk. Few studies have examined relationships between life course SES and adult structural brain changes that may be associated with cognitive decline.

AIMS

This systematic review assesses evidence from neuroimaging based epidemiological studies that have explored relationships between life course SES and adult structural brain changes.

METHODS

Embase, PsycINFO and Medline from inception to November 2020 were systematically searched according to strict search criteria which captured studies examining relationships between life course SES and adult structural neuroimaging changes. Bibliographies and citations of relevant papers were selected. Searches were limited to English language publications.

RESULTS

Amongst 8134 search results, 91 unique titles were screened and 24 studies selected. All 24 studies demonstrated at least partial relationships between disadvantaged life SES and adverse structural brain changes. Selected studies utilised diverse structural imaging techniques, neuroanatomical sites and operational definitions of life course SES. The methodological approaches and statistical analysis varied significantly between studies. We specifically discuss the neurobiological interpretation of Diffusion weighted MRI based studies and MRI volumetric studies investigating associations between life course SES and adult brain structural changes and the wider global health implications of these studies.

CONCLUSION

Disadvantaged life course SES may have associations with structural brain changes which underlie adverse ageing outcomes. Given heterogeneity of study designs and operationalisation of SES, the cross-sectional design of studies and wide-ranging neuroimaging modalities any association should be considered with caution. Mediatory mechanisms including malnutrition, stress, markers of inflammation, hormonal changes and cognitive reserve and health behaviour are presented in selected studies. Targeting life course SES in public health-based interventions may offer approaches to maintain healthy brain structure and function in ageing.

Ιnnovative Health Promotion Strategies: A 6-Month Longitudinal Study on Computerized Cognitive Training for Older Adults with Minor Neurocognitive Disorders

Minor neurocognitive disorders (NCDs) represent a transitional phase between normal cognitive aging and dementia, highlighting the importance of early interventions. This study assessed the efficacy of a structured 6-month computerized cognitive training (CCT) program in stabilizing cognitive decline among older adults with minor NCDs. One hundred participants were randomly assigned to an intervention group or a non-intervention group. The intervention group underwent weekly, personalized CCT sessions using the MeMo program, which targeted memory, attention, and adaptability. Cognitive performance was measured at baseline and after six months using the Cambridge Cognitive Examination (CAMCOG). Statistical analysis showed significant cognitive decline in the non-intervention group in orientation (p = 0.032), language expression (p = 0.008), praxis (p = 0.008), and memory (p = 0.01). In contrast, the intervention group showed no significant changes, except for a minor decline in perception (p = 0.003). These results suggest that CCT may help delay cognitive deterioration in minor NCDs. However, while cognitive decline was stabilized, no significant improvement was observed. Further research is recommended to investigate the long-term benefits and the transferability of cognitive gains. The findings support the use of CCT as a non-pharmacological health promotion strategy for enhancing cognitive resilience in aging populations. The novelty of this research lies in its focus on adaptive CCT as a non-pharmacological intervention, highlighting the potential role of neuroplasticity in delaying cognitive decline and offering new insights into personalized cognitive health strategies for aging populations.

How Can Early Stress Influence Later Alzheimer's Disease Risk? Possible Mediators and Underlying Mechanisms

Alzheimer's disease (AD) is a progressive, age-related neurodegenerative disorder to which genetic mutations and risk factors contribute. Evidence is increasing that environmental and lifestyle-related factors, such as exercise, nutrition, education, and exposure to (early-life) stress modify the onset, incidence, and progression of AD. Here, we discuss recent preclinical findings on putative substrates that can explain or contribute to the effects of stress early in life on the risk of developing AD. We focus in particular on stress hormones, neural networks, synapses, mitochondria, nutrient and lipid metabolism, adult neurogenesis, engram cell ensembles, and neuroinflammation. We discuss the idea that stress exposure early in life can alter these processes, either combined or in isolation, thereby reducing the capacity of the brain to resist deleterious consequences of, for example, amyloid-β accumulation, thereby accelerating cognitive decline and progression of Alzheimer-related changes in model systems of the disease. A better understanding of whether experiences early in life also modify trajectories of cognitive decline and pathology in AD and how the substrates discussed translate to humans may help develop novel preventive and/or therapeutic strategies to mitigate the consequences of stressors early in life and increase resilience to developing dementia.

Resilience to Alzheimer's disease associates with alterations in perineuronal nets

INTRODUCTION

Some individuals show intact cognition despite the presence of neuropathological hallmarks of Alzheimer's disease (AD). The plasticity of parvalbumin (PV)-containing interneurons might contribute to resilience. Perineuronal nets (PNNs), that is, extracellular matrix structures around neurons, modulate PV neuron function. We hypothesize that PNNs play a role in resilience to AD.

METHODS

PNN amount and morphology were determined in immunolabelled sections of the frontal cortex of control, AD and resilient subjects. Expression levels of genes related to PNNs and microglia signatures were evaluated by bulk RNA sequencing.

RESULTS

The expression of the PNN-component aggrecan around PV neurons is decreased in resilient and AD subjects, whereas PNN-sugar chains are reduced only in resilient subjects. In AD, fewer presynaptic terminals on PV neurons are detected and genes related to PNN degradation are upregulated.

DISCUSSION

These data show distinct PNN changes in individuals resilient to AD, which may contribute to preserved cognition despite the neuropathology.

HIGHLIGHTS

Aggrecan levels are decreased in the frontal cortex of AD and resilient subjects. In resilient subjects, WFA+ PNNs are reduced around neuronal somata. In AD patients, PV neurons show disrupted WFA peridendritic staining and synaptic loss. Expression levels of PNN-degrading enzymes are higher in AD. Excitatory neurons bearing a PNN show low amounts of ptau.

Maintaining a Dynamic Brain: A Review of Empirical Findings Describing the Roles of Exercise, Learning, and Environmental Enrichment in Neuroplasticity from 2017-2023

Brain plasticity, also termed neuroplasticity, refers to the brain's life-long ability to reorganize itself in response to various changes in the environment, experiences, and learning. The brain is a dynamic organ capable of responding to stimulating or depriving environments, activities, and circumstances from changes in gene expression, release of neurotransmitters and neurotrophic factors, to cellular reorganization and reprogrammed functional connectivity. The rate of neuroplastic alteration varies across the lifespan, creating further challenges for understanding and manipulating these processes to benefit motor control, learning, memory, and neural remodeling after injury. Neuroplasticity-related research spans several decades, and hundreds of reviews have been written and published since its inception. Here we present an overview of the empirical papers published between 2017 and 2023 that address the unique effects of exercise, plasticity-stimulating activities, and the depriving effect of social isolation on brain plasticity and behavior.

The concept of resilience to Alzheimer's Disease: current definitions and cellular and molecular mechanisms

Some individuals are able to maintain their cognitive abilities despite the presence of significant Alzheimer's Disease (AD) neuropathological changes. This discrepancy between cognition and pathology has been labeled as resilience and has evolved into a widely debated concept. External factors such as cognitive stimulation are associated with resilience to AD, but the exact cellular and molecular underpinnings are not completely understood. In this review, we discuss the current definitions used in the field, highlight the translational approaches used to investigate resilience to AD and summarize the underlying cellular and molecular substrates of resilience that have been derived from human and animal studies, which have received more and more attention in the last few years. From these studies the picture emerges that resilient individuals are different from AD patients in terms of specific pathological species and their cellular reaction to AD pathology, which possibly helps to maintain cognition up to a certain tipping point. Studying these rare resilient individuals can be of great importance as it could pave the way to novel therapeutic avenues for AD.

The interaction between ageing and Alzheimer's disease: insights from the hallmarks of ageing

Ageing is a crucial risk factor for Alzheimer's disease (AD) and is characterised by systemic changes in both intracellular and extracellular microenvironments that affect the entire body instead of a single organ. Understanding the specific mechanisms underlying the role of ageing in disease development can facilitate the treatment of ageing-related diseases, such as AD. Signs of brain ageing have been observed in both AD patients and animal models. Alleviating the pathological changes caused by brain ageing can dramatically ameliorate the amyloid beta- and tau-induced neuropathological and memory impairments, indicating that ageing plays a crucial role in the pathophysiological process of AD. In this review, we summarize the impact of several age-related factors on AD and propose that preventing pathological changes caused by brain ageing is a promising strategy for improving cognitive health.

The iceberg of dementia risk: empirical and conceptual arguments in favor of structural interventions for brain health

While pharmacological interventions for dementia struggle to demonstrate improved outcomes for patients and at-risk populations, non-pharmacological lifestyle interventions have been proposed as a tool to achieve dementia risk reduction. In this review, it is argued that lifestyle modification alone is a surface-level intervention from the point of view of fair and far-reaching dementia prevention. Below the tip of this "iceberg of dementia risk," there are living conditions and social structures that represent deeper contributions to risk in the population. It is argued that alongside lifestyle modification, activist research and structural interventions are needed to make our society fairer and more dementia-resilient.

Activated Wake Systems in Narcolepsy Type 1

OBJECTIVE

Narcolepsy type 1 (NT1) is assumed to be caused solely by a lack of hypocretin (orexin) neurotransmission. Recently, however, we found an 88% reduction in corticotropin-releasing hormone (CRH)-positive neurons in the paraventricular nucleus (PVN). We assessed the remaining CRH neurons in NT1 to determine whether they co-express vasopressin (AVP) to reflect upregulation. We also systematically assessed other wake-systems, since current NT1 treatments target histamine, dopamine, and norepinephrine pathways.

METHODS

In postmortem tissue of people with NT1 and matched controls, we immunohistochemically stained and quantified neuronal populations expressing: CRH and AVP in the PVN, and CRH in the Barrington nucleus; the key neuronal histamine-synthesizing enzyme, histidine decarboxylase (HDC) in the hypothalamic tuberomammillary nucleus (TMN); the rate-limited-synthesizing enzyme, tyrosine hydroxylase (TH), for dopamine in the mid-brain and for norepinephrine in the locus coeruleus (LC).

RESULTS

In NT1, there was: a 234% increase in the percentage of CRH cells co-expressing AVP, while there was an unchanged integrated optical density of CRH staining in the Barrington nucleus; a 36% increased number of histamine neurons expressing HDC, while the number of typical human TMN neuronal profiles was unchanged; a tendency toward an increased density of TH-positive neurons in the substantia nigra compacta; while the density of TH-positive LC neurons was unchanged.

INTERPRETATION

Our findings suggest an upregulation of activity by histamine neurons and remaining CRH neurons in NT1. This may explain earlier reports of normal basal plasma cortisol levels but lower levels after dexamethasone suppression. Alternatively, CRH neurons co-expressing AVP neurons are less vulnerable. ANN NEUROL 2023;94:762-771.

Overestimation of on-road driving performance is associated with reduced driving safety in older drivers

OBJECTIVES

Older drivers often show less precise self-ratings with a tendency to overestimate themselves. It is unclear, however, how overestimators differ from underestimators or drivers with adequate self-ratings.

METHODS

59 healthy older drivers participated in this on-road study. Besides standardized on-road driving assessment, the study protocol included the collection of neuropsychological and driving-related data as well as different self-ratings. Statistical analyses involved correlations between different subjective and objective ratings as well as statistical comparisons between drivers who overestimated and drivers who adequately rated their on-road driving performance (no drivers underestimated their performance).

RESULTS

Despite positive correlations between different self- and expert ratings, our results revealed that 25 % of the participants overestimated their on-road driving skills. Among other things, overestimators showed poorer on-road driving performances, more prospective near and minor at-fault accidents, poorer cognitive performances in specific driving-related domains and reduced annual mileage.

DISCUSSION

Our results suggest that older drivers who overestimate their driving skills show poorer performances within a broad range of skills that directly reflect or are closely related to driving safety. Against the background that an adequate self-assessment is required by German traffic regulations, our findings suggest that overestimators represent a risk group among the population of older drivers.

Working in old age in Mexico: Implications for Cognitive Functioning

Previous studies indicate that occupation might affect cognitive functioning in late life. As people in low and middle income countries often have to work until late life, we sought to investigate if there are cognitive benefits to working later into life and whether cognitive function deteriorates after exiting the labor force. We analyzed longitudinal data from the Mexican Health and Aging Study (MHAS), a nationally representative sample of Mexican adults age 50+ (n=7,375), that assessed cognitive functioning by verbal learning, delayed recall, and visual scanning. Analyses were carried out using mixed-effects modeling corrected for the influence of gender, IADLs, diabetes, stroke, hypertension, depression, income, and marital status. Results suggest that working actively, compared to exiting the workforce, was associated with cognitive performance only in context with occupation. Domestic workers had a faster decline in verbal learning (b=-0.02, p=0.020) and delayed recall (b=-0.02, p=0.036) if they continued working actively and people working in administration (b=0.03, p=0.007), sales (b=0.02, p=0.044), and educators (b=0.03, p=0.049) had a slower decline in visual scanning if they continued working in old age. Our findings indicate that continued participation in the labor force in old age does not necessarily come with cognitive benefits. Whether or not working actively in later life protects or even harms cognitive functioning is likely to depend on the type of job.

Group experiences of cognitive stimulation therapy (CST) in Tanzania: a qualitative study

BACKGROUND

Tanzania is a low-income country in which medication for dementia is largely unavailable. Cognitive Stimulation Therapy (CST) is a group-based psychological treatment for people with dementia (PwD), shown to improve cognition and quality of life (QoL). It has previously been culturally adapted and piloted in Tanzania, shown to produce similar outcomes. UK research into CST suggests processes inherent to the group nature are key to its success. This study sought to identify group processes within CST in Tanzania and understand their impact on CST principles and outcomes.

METHODS

Data collection took place in rural Hai District, through qualitative semi-structured interviews. Sixteen PwD and four facilitators were recruited through convenience sampling and interviewed about their experiences of CST. Interviews were audio-recorded, translated, transcribed and analysed by thematic analysis.

RESULTS

Two main themes emerged: 'Positive group experiences' and 'Negative group experiences'. From this, a number of group processes were identified, such as helping behaviours and feeling understood by the group. Positive processes supported CST principles and participant improvement. Facilitators were influential over group dynamics. The group processes identified impacted CST principles and treatment outcomes.

CONCLUSIONS

This is the first study on group mechanisms of CST in Tanzania. It provides deeper insight into participants' experiences of CST, thus identifying specific processes underlying the quantitatively measured positive outcomes of CST in Tanzania by previous studies. It also reveals further cultural barriers to implementation, enabling amendments for optimization of treatment efficacy.

Social networks and cognitive function in older adults: findings from the HAPIEE study

BACKGROUND

Social networks are associated with better cognitive health in older people, but the role of specific aspects of the social network remains unclear. This is especially the case in Central and Eastern Europe. This study examined associations between three aspects of the social network (network size of friends and relatives, contact frequency with friends and relatives, and social activity participation) with cognitive functions (verbal memory, learning ability, verbal fluency, processing speed, and global cognitive function) in older Czech, Polish, and Russian adults.

METHODS

Linear regression estimated associations between baseline social networks and cognitive domains measured at both baseline and follow-up (mean duration of follow-up, 3.5 ± 0.7 years) in 6691 participants (mean age, 62.2 ± 6.0 years; 53.7% women) from the Health, Alcohol and Psychosocial factors In Eastern Europe (HAPIEE) study.

RESULTS

Cross-sectional analyses, adjusted for country, age, and sex, showed positive associations of global cognitive function with social activity participation and network size of friends and relatives, but not with contact frequency in either network. Further adjustment for sociodemographic, behavioural, and health characteristics attenuated the associations with network size of relatives (P-trend = 0.074) but not with network size of friends (P-trend = 0.036) or social activities (P-trend< 0.001). In prospective analyses, network size and social activity participation were also linked with better cognition in simple models, but the associations were much stronger for social activities (P-trend< 0.001) than for network size of friends (P-trend = 0.095) and relatives (P-trend = 0.425). Adjustment for baseline cognition largely explained the prospective associations with network size of friends (P-trend = 0.787) and relatives (P-trend = 0.815), but it only slightly attenuated the association with social activities (P-trend< 0.001). The prospective effect of social activities was largely explained by sociodemographic, health behavioural, and health covariates (P-trend = 0.233). Analyses of specific cognitive domains generally replicated the cross-sectional and prospective findings for global cognitive function.

CONCLUSIONS

Older Central and Eastern European adults with larger social networks and greater social activities participation had better cognitive function, but these associations were stronger at baseline than over the short-term follow-up.

Association of Occupational Factors and Dementia or Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Several existing studies have reported that occupational factors might play an important part in cognitive function with aging.

OBJECTIVE

We aim to explore the associations between modifiable occupational factors and risk of dementia or mild cognitive impairment (MCI).

METHODS

Adopting random-effect models, this study conducted primary analyses for all occupational factors and subgroup analyses for the effect of occupation type based on prospective cohort and case-control studies searched from PubMed and EMBASE databases up to March 2020.

RESULTS

Among the 38,111 identified literatures, 9 studies on occupation type, 4 studies on work complexity, and 30 studies on occupational exposure were included. In terms of occupation type, mental work conferred a 44% reduced risk (95% CI = 0.34-0.94, I² = 85.00%, p < 0.01) for MCI. In terms of work complexity, higher work complexity conferred a 5% reduced risk (95% CI = 0.91-1.00, I² = 57.00%, p < 0.01) for dementia. In terms of occupational exposure, high strain and passive job in the longest-held job conferred a 1.21- and 1.15-fold excess risk (95% CI = 1.05-1.39 I² = 62.00%, p < 0.05; 95% CI = 1.05-1.26 I² = 31.00%, p = 0.23; respectively) of cognitive decline. Besides, magnetic field exposure conferred a 1.26-fold excess risk (95% CI = 1.01-1.57, I² = 69.00%, p < 0.01) for dementia.

CONCLUSION

Novel prevention strategies based on occupational factors may hold promise against dementia and MCI.

Neuropeptides of the human magnocellular hypothalamus

Hypothalamic magnocellular nuclei with their large secretory neurons are unique and phylogenetically conserved brain structures involved in the continual regulation of important homeostatic and autonomous functions in vertebrate species. Both canonical and newly identified neuropeptides have a broad spectrum of physiological activity at the hypothalamic neuronal circuit level located within the supraoptic (SON) and paraventricular (PVN) nuclei. Magnocellular neurons express a variety of receptors for neuropeptides and neurotransmitters and therefore receive numerous excitatory and inhibitory inputs from important subcortical neural areas such as limbic and brainstem populations. These unique cells are also densely innervated by axons from other hypothalamic nuclei. The vast majority of neurochemical maps pertain to animal models, mainly the rodent hypothalamus, however accumulating preliminary anatomical structural studies have revealed the presence and distribution of several neuropeptides in the human magnocellular nuclei. This review presents a novel and comprehensive evidence based evaluation of neuropeptide expression in the human SON and PVN. Collectively this review aims to cast a new, medically oriented light on hypothalamic neuroanatomy and contribute to a better understanding of the mechanisms responsible for neuropeptide-related physiology and the nature of possible neuroendocrinal interactions between local regulatory pathways.

Physical activity and cognitive stimulation ameliorate learning and motor deficits in a transgenic mouse model of Alzheimer's disease

Epidemiological studies suggest that physical exercise or cognitive stimulation might contribute to lower the risk of developing dementia disorders such as Alzheimer's disease (AD). Here, we used the well-established enrichment environment (EE) paradigm to study the impact of prolonged physical activity and cognitive stimulation in a mouse model of AD overexpressing only Aβ_4-42 peptides. These mice display age-dependent memory and motor deficits, in the absence of human amyloid precursor protein (APP) overexpression. We demonstrate that housing under EE conditions leads to an entire preservation of recognition and spatial memory, as well as a rescue of motor deficits in this mouse model. Moreover, we find that Tg4-42^hom mice present a typical floating phenotype in the Morris water maze task that could be completely ameliorated upon long-term EE housing. Our findings are in line with epidemiological studies suggesting that physical activity and cognitive stimulation might represent efficient strategies to prevent age-related neurodegenerative disorders such as AD.

Resting EEG, Hair Cortisol and Cognitive Performance in Healthy Older People with Different Perceived Socioeconomic Status

Successful aging depends upon several internal and external factors that influence the overall aging process. Objective and subjective socioeconomic status emerge as potential psychosocial factors in the ethiopathophysiology of aging-related disorders. Presumably, low socioeconomic status can act as a psychosocial stressor that can affect humans’ physiology via psychoneuroendocrine mechanisms, that may, in turn, affect the brain physiology. In resting-state electroencephalography (EEG), excess theta and delta activity has been related to cognitive decline and dementia. The main aim of this study was to analyze the effect of objective and subjective socioeconomic status (SES) on cognition and brain electrical activity through EEG measures. The present research constitutes a cross-sectional study with thirty healthy older adults (61–82 years old) separated into two clusters: high socioeconomic (HS) and low socioeconomic (LS) status; they were evaluated and compared in cognitive terms using the Wechsler Adult Intelligence Scale (WAIS-IV). An EEG at rest was recorded to measure brain activity and, as an indicator of long-term stress exposure, hair cortisol concentrations (HCC) were measured. Our results show that lower SES is related to a worse performance in working memory tasks (p = 0.009), higher delta (p = 0.002) and theta power (p = 0.039), and lower alpha activity (p = 0.028). However, it seems that SES does not significantly affect HCC in this population of healthy older adults. The effects of SES on long-term cortisol exposure, brain electrical activity, and cognitive functions in healthy older people emphasize the role of psychosocial factors in aging from an integrative perspective that will allow us to implement better prevention programs to target cognitive decline in adults.

The Effects of Cognitive Training on Brain Network Activity and Connectivity in Aging and Neurodegenerative Diseases: a Systematic Review

Cognitive training (CT) is an increasingly popular, non-pharmacological intervention for improving cognitive functioning in neurodegenerative diseases and healthy aging. Although meta-analyses support the efficacy of CT in improving cognitive functioning, the neural mechanisms underlying the effects of CT are still unclear. We performed a systematic review of literature in the PubMed, Embase and PsycINFO databases on controlled CT trials (N > 20) in aging and neurodegenerative diseases with pre- and post-training functional MRI outcomes up to November 23rd 2018 (PROSPERO registration number CRD42019103662). Twenty articles were eligible for our systematic review. We distinguished between multi-domain and single-domain CT. CT induced both increases and decreases in task-related functional activation, possibly indicative of an inverted U-shaped curve association between regional brain activity and task performance. Functional connectivity within ‘cognitive’ brain networks was consistently reported to increase after CT while a minority of studies additionally reported increased segregation of frontoparietal and default mode brain networks. Although we acknowledge the large heterogeneity in type of CT, imaging methodology, in-scanner task paradigm and analysis methods between studies, we propose a working model of the effects of CT on brain activity and connectivity in the context of current knowledge on compensatory mechanisms that are associated with aging and neurodegenerative diseases.

Application of T1-/T2-Weighted Ratio Mapping to Elucidate Intracortical Demyelination Process in the Alzheimer's Disease Continuum

Background The biological diagnosis criteria of the Alzheimer’s disease (AD) suggests that previous work may misclassify the cognitive impairment caused by other factors into AD. Consequently, re-assessing the imaging profile of AD continuum is needed. Considering the high vulnerability of cortical association fibers, we aimed to elucidate the cortical demyelination process in the AD continuum biologically defined.

Methods According to the biological diagnosis criteria, we determined the positive amyloid status (A+) as cerebrospinal fluid (CSF) amyloid_1–42 < 192 pg/ml, Florbetapir Positron emission tomography (PET) composite standardized uptake value ratio (SUVR) >1.11. Also, the positive Tau status (T+) was determined as p-Tau₁₈₁ > 23 pg/ml. Based on the cognitive characterization, we further categorized 252 subjects into 27 cognitively unimpaired with normal AD biomarkers (A−T−, controls), 49 preclinical AD (A+T+), 113 AD with mild cognitive impairment (MCI) (A+T+), and 63 AD dementia (A+T+). We estimated the intracortical myelin content used the T1- and T2-weighted (T1W/T2W) ratio mapping. To investigate the sensitivity of the ratio mapping, we also utilized well-validated AD imaging biomarkers as the reference, including gray matter volume and Fludeoxyglucose PET (FDG-PET). Based on the general linear model, we conducted the voxel-wise two-sample T-tests between the controls and each group in the AD continuum.

Results Compared to the controls, the results showed that the preclinical AD patients exhibited decreased T1W/T2W ratio value in the right inferior parietal lobule (IPL); as the disease progresses, the prodromal AD patients demonstrated lower ratio value in bilateral IPL, with hippocampus (HP) atrophy. Lastly, the AD dementia patients exhibited decreased ratio value in bilateral IPL and hippocampus; also, we observed the bilateral temporal cortices atrophy and widespread decreased metabolism in the AD dementia patients. After corrected with gray volume, the results remained mostly unchanged.

Conclusion Our study implied the decreased right IPL T1W/T2W ratio might represent early AD-related demyelination in disease continuum. Additionally, we demonstrated that the T1W/T2W ratio mapping is an easy-to-implement and sensitive metric to assess the intracortical myelin content in AD, particularly in the early stage.

Plastic changes in brain morphology in relation to learning and environmental enrichment in the guppy (Poecilia reticulata)

Despite the common assumption that the brain is malleable to surrounding conditions mainly during ontogeny, plastic neural changes can occur also in adulthood. One of the driving forces responsible for alterations in brain morphology is increasing environmental complexity that may demand enhanced cognitive abilities (e.g. attention, memory and learning). However, studies looking at the relationship between brain morphology and learning are scarce. Here, we tested the effects of both learning and environmental enrichment on neural plasticity in guppies (Poecilia reticulata), by means of either a reversal-learning test or a spatial-learning test. Given considerable evidence supporting environmentally induced plastic alterations, two separate control groups that were not subjected to any cognitive test were included to account for potential changes induced by the experimental setup alone. We did not find any effect of learning on any of our brain measurements. However, we found strong evidence for an environmental effect, where fish given access to the spatial-learning environment had larger relative brain size and optic tectum size in relation to those exposed to the reversal-learning environment. Our results demonstrate the plasticity of the adult brain to respond adaptively mainly to environmental conditions, providing support for the environmental enhancement theory.

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.

Vulnerability and resilience to Alzheimer's disease: early life conditions modulate neuropathology and determine cognitive reserve

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a high prevalence among the elderly and a huge personal and societal impact. Recent epidemiological studies have indicated that the incidence and age of onset of sporadic AD can be modified by lifestyle factors such as education, exercise, and (early) stress exposure. Early life adversity is known to promote cognitive decline at a later age and to accelerate aging, which are both primary risk factors for AD. In rodent models, exposure to 'negative' or 'positive' early life experiences was recently found to modulate various measures of AD neuropathology, such as amyloid-beta levels and cognition at later ages. Although there is emerging interest in understanding whether experiences during early postnatal life also modulate AD risk in humans, the mechanisms and possible substrates underlying these long-lasting effects remain elusive.

METHODS

We review literature and discuss the role of early life experiences in determining later age and AD-related processes from a brain and cognitive 'reserve' perspective. We focus on rodent studies and the identification of possible early determinants of later AD vulnerability or resilience in relation to early life adversity/enrichment.

RESULTS

Potential substrates and mediators of early life experiences that may influence the development of AD pathology and cognitive decline are: programming of the hypothalamic-pituitary-adrenal axis, priming of the neuroinflammatory response, dendritic and synaptic complexity and function, overall brain plasticity, and proteins such as early growth response protein 1 (EGR1), activity regulated cytoskeleton-associated protein (Arc), and repressor element-1 silencing transcription factor (REST).

CONCLUSIONS

We conclude from these rodent studies that the early postnatal period is an important and sensitive phase that influences the vulnerability to develop AD pathology. Yet translational studies are required to investigate whether early life experiences also modify AD development in human studies, and whether similar molecular mediators can be identified in the sensitivity to develop AD in humans.

Regional brain volumetry and brain function in severely brain-injured patients

OBJECTIVE

The relationship between residual brain tissue in patients with disorders of consciousness (DOC) and the clinical condition is unclear. This observational study aimed to quantify gray (GM) and white matter (WM) atrophy in states of (altered) consciousness.

METHODS

Structural T1-weighted magnetic resonance images were processed for 102 severely brain-injured and 52 healthy subjects. Regional brain volume was quantified for 158 (sub)cortical regions using Freesurfer. The relationship between regional brain volume and clinical characteristics of patients with DOC and conscious brain-injured patients was assessed using a linear mixed-effects model. Classification of patients with unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) using regional volumetric information was performed and compared to classification using cerebral glucose uptake from fluorodeoxyglucose positron emission tomography. For validation, the T1-based classifier was tested on independent datasets.

RESULTS

Patients were characterized by smaller regional brain volumes than healthy subjects. Atrophy occurred faster in UWS compared to MCS (GM) and conscious (GM and WM) patients. Classification was successful (misclassification with leave-one-out cross-validation between 2% and 13%) and generalized to the independent data set with an area under the receiver operator curve of 79% (95% confidence interval [CI; 67-91.5]) for GM and 70% (95% CI [55.6-85.4]) for WM.

INTERPRETATION

Brain volumetry at the single-subject level reveals that regions in the default mode network and subcortical gray matter regions, as well as white matter regions involved in long range connectivity, are most important to distinguish levels of consciousness. Our findings suggest that changes of brain structure provide information in addition to the assessment of functional neuroimaging and thus should be evaluated as well. Ann Neurol 2018;83:842-853.

Education as a Protective Factor Moderating the Effect of Depression on Memory Impairment in Elderly Women

OBJECTIVE

The cognitive reserve theory explicates individual differences observed in the clinical manifestation of dementia despite similar brain pathology. Education, a popular proxy of the cognitive reserve, has been shown to have protective effects delaying the onset of clinical symptoms including memory. This study was conducted to test whether education can moderate the negative effect of depressive mood on memory performance in elderly women residing in the community.

METHODS

29 elderly "unschooled" female (less than 6 years of formal education) and 49 "schooled" female (6 or more years) people were compared with regard to association between depressive mood and verbal memory functioning, which were measured by the Geriatric Depression Scale and the Elderly Verbal Learning Test, respectively.

RESULTS

The results showed that completing or receiving more than primary school education significantly reduced the negative association between depressive mood and memory performance. Participants who did not complete primary schooling showed a decline in memory test scores depending on the level of depressive mood; whereas participants who have completed or received more than primary education displayed relatively stable memory function despite varying level of depressive mood.

CONCLUSION

Our findings imply that education in early life may have protective effects against memory impairment related to elderly depression.

Association between exercise and the risk of dementia: results from a nationwide longitudinal study in China

OBJECTIVE

This study was conducted to examine the causal association between exercise and the risk of dementia among older Chinese adults.

DESIGN

Longitudinal population-based study with a follow-up duration of 9 years.

SETTING

Data for the Chinese Longitudinal Healthy Longevity Survey waves occurring from 2002 to 2011-2012 were extracted from the survey database.

PARTICIPANTS

In total, 7501 dementia-free subjects who were older than 65 years were included at baseline. Dementia was defined as a self-reported or proxy-reported physician's diagnosis of the disease.

OUTCOME MEASURES AND METHODS

Regular exercise and potential confounding variables were obtained via a self-report questionnaire. We generated longitudinal logistic regression models based on time-lagged generalised estimating equation to examine the causal association between exercise and dementia risk.

RESULTS

Of the 7501 older Chinese people included in this study, 338 developed dementia during the 9-year follow-up period after excluding those who were lost to follow-up or deceased. People who regularly exercised had lower odds of developing dementia (OR=0.53, 95% CI 0.33 to 0.85) than those who did not exercise regularly.

CONCLUSION

Regular exercise was associated with decreased risk of dementia. Policy-makers should develop effective public health programmes and build exercise-friendly environments for the general public.

Brain functional connectivity difference in the complete network of an entire village: the role of social network size and embeddedness

Social networks are known to protect cognitive function in old age. For the first time, this study examines how social network size and social network embeddedness measured by k-core score are associated with functional connectivity in the brain using the complete social network of an entire village. According to the results, social network size has both positive and negative associations with functional connectivity; showing no meaningful pattern relative to distance among brain regions. However, older adults deeply embedded in the complete network tend to maintain functional connectivity between long-distance regions even after controlling for other covariates such as age, gender, education, and Mini-Mental State Examination score. Network Based Statistics (NBS) also revealed strong and consistent evidence that social network embeddedness has component-level associations with functional connectivity among brain regions, especially between inferior prefrontal and occipital/parietal lobes.

Support at Home: Interventions to Enhance Life in Dementia (SHIELD) – evidence, development and evaluation of complex interventions

Background

Dementia is a national priority and this research addresses the Prime Minister’s commitment to dementia research as demonstrated by his 2020 challenge and the new UK Dementia Research Institute. In the UK > 800,000 older people have dementia. It has a major impact on the lives of people with dementia themselves, on the lives of their family carers and on services, and costs the nation £26B per year. Pharmacological cures for dementias such as Alzheimer’s disease are not expected before 2025. If no cure can be found, the ageing demographic will result in 2 million people living with dementia by 2050. People with dementia lose much more than just their memory and their daily living skills; they can also lose their independence, their dignity and status, their confidence and morale, and their roles both within the family and beyond. They can be seen as a burden by society, by their families and even by themselves, and may feel unable to contribute to society. This programme of research aims to find useful interventions to improve the quality of life of people with dementia and their carers, and to better understand how people with dementia can be supported at home and avoid being admitted to hospital.

Objectives

(1) To develop and evaluate the maintenance cognitive stimulation therapy (MCST) for people with dementia; (2) to develop the Carer Supporter Programme (CSP), and to evaluate the CSP and Remembering Yesterday, Caring Today (RYCT) for people with dementia both separately and together in comparison with usual care; and (3) to develop a home treatment package (HTP) for dementia, to field test the HTP in practice and to conduct an exploratory trial.

Methods

(1) The MCST programme was developed for people with dementia based on evidence and qualitative work. A randomised controlled trial (RCT) [with a pilot study of MCST plus acetylcholinesterase inhibitors (AChEIs)] compared MCST with cognitive stimulation therapy (CST) only. The MCST implementation study conducted a trial of outreach compared with usual care, and assessed implementation in practice. (2) The CSP was developed based on existing evidence and the engagement of carers of people with dementia. The RCT (with internal pilot) compared the CSP and reminiscence (RYCT), both separately and in combination, with usual care. (3) A HTP for dementia, including the most promising interventions and components, was developed by systematically reviewing the literature and qualitative studies including consensus approaches. The HTP for dementia was evaluated in practice by conducting in-depth field testing.

Results

(1) Continuing MCST improved quality of life and improved cognition for those taking AChEIs. It was also cost-effective. The CST implementation studies indicated that many staff will run CST groups following a 1-day training course, but that outreach support helps staff go on to run maintenance groups and may also improve staff sense of competence in dementia care. The study of CST in practice found no change in cognition or quality of life at 8-month follow-up. (2) The CSP/RYCT study found no benefits for family carers but improved quality of life for people with dementia. RYCT appeared beneficial for the quality of life of people with dementia but at an excessively high cost. (3) Case management for people with dementia reduces admissions to long-term care and reduces behavioural problems. In terms of managing crises, staff suggested more costly interventions, carers liked education and support, and people with dementia wanted family support, home adaptations and technology. The easy-to-use home treatment manual was feasible in practice to help staff working in crisis teams to prevent hospital admissions for people with dementia.

Limitations

Given constraints on time and funding, we were unable to compete the exploratory trial of the HTP package or to conduct an economic evaluation.

Future research

To improve the care of people with dementia experiencing crises, a large-scale clinical trial of the home treatment manual is needed.

Conclusion

There is an urgent need for effective psychosocial interventions for dementia. MCST improved quality of life and was cost-effective, with benefits to cognition for those on AChEIs. MCST was feasible in practice. Both CSP and RYCT improved the quality of life of people with dementia, but the overall costs may be too high. The HTP was useful in practice but requires evaluation in a full trial. Dementia care research may improve the lives of millions of people across the world.

Trial registrations

Current Controlled Trials ISRCTN26286067 (MCST), ISRCTN28793457 (MCST implementation) and ISRCTN37956201 (CSP/RYCT).

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 5, No. 5. See the NIHR Journals Library website for further project information.

Which types of mental work demands may be associated with reduced risk of dementia?

INTRODUCTION

Previous studies have demonstrated that an overall high level of mental work demands decreased dementia risk. In our study, we investigated whether this effect is driven by specific mental work demands and whether it is exposure dependent.

METHODS

Patients aged 75+ years were recruited from general practitioners and participated in up to seven assessment waves (every 1.5 years) of the longitudinal AgeCoDe study. Analyses of the impact of specific mental work demands on dementia risk were carried out via multivariate regression modeling (n = 2315).

RESULTS

We observed a significantly lower dementia risk in individuals with a higher level of "information processing" (HR, 0.888), "pattern detection" (HR, 0.878), "mathematics" (HR, 0.878), and "creativity" (HR, 0.878). Yet, exposure-dependent effects were only significant for "information processing" and "pattern detection."

DISCUSSION

Our longitudinal observations suggest that dementia risk may be reduced by some but not all types of mental work demands.

The effects of peripheral tactile stimulation on memory in patients with probable Alzheimer's disease

The authors investigated whether peripheral tactile nerve stimulation might improve memory in patients with iProbable Alzheimer s disease. The hypothesis was derived from animal studies in which peripheral stimulation resulted in activation of septo-hippocampal neurons. Our data meveal that tactile stimulation improved visual short-term, visual long-!erm, and verbal long-term mem orv in Alzheimer patients. In addition, an enhancement in verbal fluency was demonstrated. After a period of six weeks without stimulation, nio noticeable effects remained.

Effects of peripheral tactile nerve stimulation on affective behavior of patients with probable Alzheimer's disease

In the present study, the hypothesis was tested that peripheral tactile nerve stimulation by massage would improve various aspects of affective behavior in patients with probable Alzheimer's disease. It was assumed that peripheral tactile stimulation might activate higher-level brain structures (e.g. the hypothalamus). The present study revealed that patients who were stimulated with tactile stimulation felt less depressed, less anxious, more well tempered, and were more alert. Apart from that, their personal orientation and their environmental orientation in place improved, they were more interested in social contacts and they participated more in activities of daily living. However, the observed effects could not be maintained over a period of six weeks following treatment.

Age-related changes in pial arterial structure and blood flow in mice

Age-related cerebral blood flow decreases are thought to deteriorate cognition and cause senescence, although the related mechanism is unclear. To investigate the relationships between aging and changes in cerebral blood flow and vasculature, we obtained fluorescence images of young (2-month-old) and old (12-month-old) mice using indocyanine green (ICG). First, we found that the blood flow in old mice's brains is lower than that in young mice and that old mice had more curved pial arteries and fewer pial artery junctions than young mice. Second, using Western blotting, we determined that the ratio of collagen to elastin (related to cerebral vascular wall distensibility) increased with age. Finally, we found that the peak ICG intensity and blood flow index decreased, whereas the mean transit time increased, with age in the middle cerebral artery and superior sagittal sinus. Age-related changes in pial arterial structure and composition, concurrent with the observed changes in the blood flow parameters, suggest that age-related changes in the cerebral vasculature structure and distensibility may induce altered brain blood flow.

Time-place learning over a lifetime: absence of memory loss in trained old mice

Time–place learning (TPL) offers the possibility to study the functional interaction between cognition and the circadian system with aging. With TPL, animals link biological significant events with the location and the time of day. This what–where–when type of memory provides animals with an experience-based daily schedule. Mice were tested for TPL five times throughout their lifespan and showed (re)learning from below chance level at the age of 4, 7, 12, and 18 mo. In contrast, at the age of 22 mo these mice showed preservation of TPL memory (absence of memory loss), together with deficiencies in the ability to update time-of-day information. Conversely, the majority of untrained (naïve) mice at 17 mo of age were unable to acquire TPL, indicating that training had delayed TPL deficiencies in the mice trained over lifespan. Two out of seven naïve mice, however, compensated for correct performance loss by adapting an alternative learning strategy that is independent of the age-deteriorating circadian system and presumably less cognitively demanding. Together, these data show the age-sensitivity of TPL, and the positive effects of repeated training over a lifetime. In addition, these data shed new light on aging-related loss of behavioral flexibility to update time-of-day information.

Service users' involvement in the development of individual Cognitive Stimulation Therapy (iCST) for dementia: a qualitative study

Background

Individual Cognitive Stimulation Therapy (iCST) is a one to one, carer led psychosocial intervention for people with dementia, adapted from group Cognitive Stimulation Therapy (CST). It is increasingly recognised that involving service users in research is key to developing interventions and treatments that successfully address their needs. This study describes the contribution of people with dementia and carers during the development phase of the intervention and materials.

Methods

Twenty-eight people with dementia and 24 carers were consulted in a series of six focus groups and 10 interviews. The purpose of this study was to gain insight into perceptions of mental stimulation from the point of view of carers and people with dementia, to ensure the materials are easy to use, clear, and appropriately tailored to the needs of people with dementia and their carers, and to assess the feasibility of the intervention.

Results

The importance of mental stimulation was emphasized by carers and people with dementia. People with dementia saw activities as a way of ‘keeping up to date’ and spending time in a meaningful way. Carers reported benefits such as improved quality of life, mood and memory. The concept of iCST was well received, and both carers and people with dementia responded positively to the first drafts of materials. Feasibility issues, such as finding time to do sessions, were identified.

Conclusion

The feedback from the focus groups and interviews will be used to further develop and refine the iCST programme materials in preparation for a field testing phase prior to a large scale randomized controlled trial (RCT).

Trial registration

ISRCTN65945963. Date of registration: 05/05/2010.

Axonal tract tracing for delineating interacting brain regions: implications for Alzheimer's disease-associated memory

We are studying the projections from the entorhinal cortex to the hippocampal formation in the mouse. The dentate gyrus is innervated by the lateral entorhinal cortex (lateral perforant path) and medial entorhinal cortex (medial perforant path). The entorhinal cortex also projects to hippocampal areas CA3 and CA1, and to the subiculum. In young transgenic Alzheimer's disease mouse models (before amyloid-β pathology), the connections are not different from normal mice. In Alzheimer's disease mice with pathology, two changes occur: first, dystrophic axon endings appear near amyloid-β plaques, and second, there are sparse aberrant axon terminations not in the appropriate area or lamina of the hippocampus. Furthermore, MRI-diffusion tensor imaging analysis indicates a decrease in the quality of the white matter tracts connecting the hippocampus to the brain; in other words, the fimbria/fornix and perforant path. Similar changes in white matter integrity have been found in Alzheimer's disease patients and could potentially be used as early indicators of disease onset.

Reactivation of atrophic neurons in Alzheimer's disease

Decreased metabolic rate may precede cognitive impairment in Alzheimer's disease (AD) and is thus an early occurring hallmark. Several observations in post-mortem brain indicate that activated neurons are better able to withstand aging and AD, a phenomenon paraphrased by us as 'use it or lose it'. Moreover, a number of pharmacological and nonpharmacological studies support the concept that activation of the brain has beneficial effects and may to a certain degree restore several aspects of cognition and other central functions. For instance, the circadian system may be restimulated in Alzheimer patients by exposing them to more light or transcutaneous nerve stimulation. A procedure has been developed to culture human post-mortem brain tissue that allows testing of the efficacy of putative stimulatory compounds such as neurotrophins.

Neurotrophin receptor p75 mediates the uptake of the amyloid beta (Aβ) peptide, guiding it to lysosomes for degradation in basal forebrain cholinergic neurons

A fascinating yet perhaps overlooked trait of the p75 neurotrophin receptor (p75(NTR)) is its ability to bind ligands with no obvious neurotrophic function. Using cultured basal forebrain (BF) neurons, this study demonstrates selective internalization of amyloid β (Aβ) 1-42 in conjunction with p75(NTR) (labelled with IgG192-Cy3) by cholinergic cells. Active under resting conditions, this process was enhanced by high K(+) stimulation and was insensitive to inhibitors of regulated synaptic activity-tetrodotoxin or botulinum neurotoxins (BoNT type/A and/B). Blockade of sarco-endoplasmic reticulum (SERCA) Ca(2+) ATPase with thapsigargin and CPA or chelation of Ca(2+) with EGTA-AM strongly suppressed the endocytosis of p75(NTR), implicating the role of ER released Ca(2+). The uptake of IgG192-Cy3 was also reduced by T-type Ca(2+) channel blocker mibefradil but not Cd(2+), an indiscriminate blocker of high voltage-activated Ca(2+) currents. A strong co-localization of IgG192-Cy3 with late endosome (Rab7) or lysosome (Lamp1) qualifier proteins suggest these compartments as the primary destination for internalized IgG192 and Aβ. Selective uptake and labeling of BF cholinergic cells with IgG192-Cy3 injected into the prefrontal cortex was verified also in vivo. The significance of these findings in relation to Aβ clearance in the cerebral cortex and pathophysiology of Alzheimer's disease is discussed.

A dynamic auditory-cognitive system supports speech-in-noise perception in older adults

Understanding speech in noise is one of the most complex activities encountered in everyday life, relying on peripheral hearing, central auditory processing, and cognition. These abilities decline with age, and so older adults are often frustrated by a reduced ability to communicate effectively in noisy environments. Many studies have examined these factors independently; in the last decade, however, the idea of an auditory-cognitive system has emerged, recognizing the need to consider the processing of complex sounds in the context of dynamic neural circuits. Here, we used structural equation modeling to evaluate the interacting contributions of peripheral hearing, central processing, cognitive ability, and life experiences to understanding speech in noise. We recruited 120 older adults (ages 55-79) and evaluated their peripheral hearing status, cognitive skills, and central processing. We also collected demographic measures of life experiences, such as physical activity, intellectual engagement, and musical training. In our model, central processing and cognitive function predicted a significant proportion of variance in the ability to understand speech in noise. To a lesser extent, life experience predicted hearing-in-noise ability through modulation of brainstem function. Peripheral hearing levels did not significantly contribute to the model. Previous musical experience modulated the relative contributions of cognitive ability and lifestyle factors to hearing in noise. Our models demonstrate the complex interactions required to hear in noise and the importance of targeting cognitive function, lifestyle, and central auditory processing in the management of individuals who are having difficulty hearing in noise.

An examination of the mechanisms underlying the effects of physical activity on brain and cognition

Physical activity positively influences brain health and cognitive functioning in older adults. Several physiological and psychological mechanisms have been identified to underlie such a relationship. Cardiovascular fitness is accompanied with changes in mechanisms such as cerebral blood flow, neurotrophic factors, neurotransmitter systems and neural architecture that have themselves been associated with cognitive performance. Factors associated with exercise such as arousal, mood and self-perception of competence seem also to influence cognitive performance. Other explanation for the benefits of exercise in cognition, results from the fact that the performance of motor skills involve an important cognitive component (e.g., executive functions and information processing speed). Evidence of brain plasticity and behavior has been provided from studies where animals are exposed to enriched or complex environments. Exposure to such paradigms in which physical activity plays an important role has been found to influence various aspects of brain function and structure. Studies using neuroimaging techniques have established a link between the acquisition of different motor skills and the occurrence of neuroplasticity in human adults. This literature review indicates that the type of exercise and its specific perceptual and cognitive characteristics may influence cognitive performance. However, most of the research has been focused on self-paced movements or automatized skills and few intervention studies have examined the results of merging exercise and cognitive training in a single program. An important scientific challenge for the coming years is to design exercise programs capable of mobilizing several type of mechanisms underlying the effects of physical activity on brain and cognition.

Autonomic responses to pain in aging and dementia

Increasing age and dementia are accompanied by an increased risk for undertreatment of pain owing to difficulty in assessing pain. Registration of autonomic responses to pain may contribute to a more reliable pain assessment. The aim of this review was to gain more insight into autonomic responses to pain in older persons with and without dementia. Literature searches were performed in the online databases MEDLINE and Web of Science. Seven studies on autonomic responses to pain in older people with or without dementia were included in the review. Autonomic responses to pain are present in older people with and without dementia, although they may be attenuated. Because no distinction could be made between different dementia subtypes based on these studies, predictions of changes in autonomic responses to pain have been made based on neuropathological changes. It can be concluded that autonomic responses to pain are attenuated in older people with and without dementia. Studies to specify the changes in the different autonomic responses for the different dementia subtypes are needed.

The impact of Cognitive Stimulation Therapy groups on people with dementia: views from participants, their carers and group facilitators

OBJECTIVES

Cognitive Stimulation Therapy (CST) can lead to significant improvements in cognitive function and quality of life for people with dementia. This study sought to investigate whether improvements found in clinical trials were also noted by people with dementia, their carers and group facilitators in everyday life.

METHOD

Qualitative interviews and focus groups were conducted with people attending CST groups, their carers and the group facilitators. Data were recorded and transcribed, before being analysed using Framework Analysis.

RESULTS

Two main themes emerged, 'Positive experiences of being in the group' and 'Changes experienced in everyday life', along with seven sub-themes. The overall experience of attending CST was seen as being emotionally positive and most participants reported some cognitive benefits.

CONCLUSIONS

The findings lend further support to previous quantitative findings, as well as providing information about the personal experience of CST.

A life course model of cognitive activities, socioeconomic status, education, reading ability, and cognition

OBJECTIVES

To cross-sectionally quantify the contribution of proxy measures of cognitive reserve reflective of the lifespan, such as education, socioeconomic status (SES), reading ability, and cognitive activities, in explaining late-life cognition.

DESIGN

Prospective observational cohort study of aging.

SETTING

Retirement communities across the Chicago metropolitan area.

PARTICIPANTS

Nine hundred fifty-one older adults free of clinical dementia in the Rush Memory and Aging Project (aged 79 ± 8, 74% female).

MEASUREMENTS

Baseline data on multiple life course factors included early-, mid-, and late-life participation in cognitive activities; early-life and adult SES; education; and reading ability (National Adult Reading Test; NART). Path analysis quantified direct and indirect standardized effects of life course factors on global cognition and five cognitive domains (episodic memory, semantic memory, working memory, visuospatial ability, perceptual speed).

RESULTS

Adjusting for age, sex, and race, education had the strongest association with global cognition, episodic memory, semantic memory, and visuospatial ability, whereas NART (followed by education) had the strongest association with working memory. Late-life cognitive activities had the strongest association with perceptual speed, followed by education.

CONCLUSIONS

These cross-sectional findings suggest that education and reading ability are the most-robust proxy measures of cognitive reserve in relation to late-life cognition. Additional research leveraging path analysis is warranted to better understand how these life course factors, reflecting the latent construct of cognitive reserve, affect abnormal cognitive aging.

A critical time window for the survival of neural progenitor cells by HDAC inhibitors in the hippocampus

Histone deacetylase inhibitors (HDACIs) that modulate gene expression by inhibiting HDAC enzymes may contribute to the survival of immature hippocampal neurons. However, it remains unknown how and when HDACIs regulate the survival of newly generated immature hippocampal neurons. In the present study, if the treatment of valproic acid (VPA) and sodium butyrate (SBt) in the specific time window during the development of newly generated n eurons r esulted in the i ncreased survival of bromodeoxyuridine (BrdU)(+) neurons in the dentate gyrus (DG) of hippocampus in mice was investigated. It was found that the number of BrdU(+) cells, the expressions of anti-apoptotic Bcl-2 family members and pCREB [D1] were increased by HDACIs when HDACIs were treated no later than 2-3 weeks after BrdU labeling. This suggests that epigenetic modification within a specific time window is critical for the survival of newborn hippocampal neurons by inhibiting the apoptotic pathway.