Stress, memory, and the hippocampus: can't live with it, can't live without it

Cognitive Disorders in Type 1 Diabetes: Role of Brain Glucose Variation, Insulin Activity, and Glucocorticoid Exposure

BACKGROUND

The number of patients with type 2 diabetes (T2D) and type 1 diabetes (T1D) is on the rise, partly due to a global increase in new T1D cases among children. Beyond the well-documented microvascular and macrovascular complications, there is now substantial evidence indicating that diabetes also impacts the brain, leading to neuropsychological impairments. The risk of developing neuropsychiatric symptoms is notably higher in childhood due to the ongoing maturation of the brain, which makes it more susceptible to damage. Despite this awareness, the specific effects of diabetes on cognitive function remain poorly understood.

SUMMARY

This review synthesizes literature on the impact of diabetes on cognition and its relationship with brain structural changes. It presents data and hypotheses to explain how T1D contributes to cognitive dysfunction, with a particular focus on children and adolescents. The emphasis on the pediatric population is intentional, as young diabetic patients typically have fewer comorbidities, reducing confounding factors and simplifying the investigation of cognitive alterations.

KEY MESSAGE

We examine the roles of hypo- and hyperglycemia, as well as the emerging role of glucocorticoids in the development of neuropsychological disorders. When specific mechanisms related to T1D are available, they are highlighted; otherwise, data and hypotheses applicable to both T1D and T2D are discussed.

Hippocampal and limbic microstructure changes associated with stress across the lifespan: a UK biobank study

Experiencing highly stressful events can have detrimental and lasting effects on brain morphology. The current study explores the effects of stress during childhood and adulthood on grey matter macro- and microstructure using a sub-sample of 720 participants from the UK Biobank with very high or very low childhood and adulthood stress scores. We used T1-weighted and diffusion MRI data to assess grey matter macro- and microstructure within bilateral hippocampus, amygdala and thalamus. Findings showed that childhood stress is associated with changes in microstructural measures bilaterally within the hippocampus and amygdala. No effects of adulthood stress on brain microstructure were found. No interaction effects between sex and stress (either childhood or adulthood) were observed for any brain imaging measure. Analysis of sub-segments of the hippocampus showed that childhood stress predominantly impacted the bilateral heads of the hippocampus. Overall, these findings suggest that highly stressful experiences during childhood, but not adulthood, have lasting impact on brain microstructure. The effects of these experiences in childhood appear to persist regardless of experiences of high or low stress in adulthood.

In vivo structural connectivity of the reward system along the hippocampal long axis

Recent work has identified a critical role for the hippocampus in reward-sensitive behaviors, including motivated memory, reinforcement learning, and decision-making. Animal histology and human functional neuroimaging have shown that brain regions involved in reward processing and motivation are more interconnected with the ventral/anterior hippocampus. However, direct evidence examining gradients of structural connectivity between reward regions and the hippocampus in humans is lacking. The present study used diffusion MRI (dMRI) and probabilistic tractography to quantify the structural connectivity of the hippocampus with key reward processing regions in vivo. Using a large sample of subjects (N = 628) from the human connectome dMRI data release, we found that connectivity profiles with the hippocampus varied widely between different regions of the reward circuit. While the dopaminergic midbrain (ventral tegmental area) showed stronger connectivity with the anterior versus posterior hippocampus, the ventromedial prefrontal cortex showed stronger connectivity with the posterior hippocampus. The limbic (ventral) striatum demonstrated a more homogeneous connectivity profile along the hippocampal long axis. This is the first study to generate a probabilistic atlas of the hippocampal structural connectivity with reward-related networks, which is essential to investigating how these circuits contribute to normative adaptive behavior and maladaptive behaviors in psychiatric illness. These findings describe nuanced structural connectivity that sets the foundation to better understand how the hippocampus influences reward-guided behavior in humans.

The autobiographical memory system and chronic pain: A neurocognitive framework for the initiation and maintenance of chronic pain

Chronic pain affects approximately 20% of the world's population, exerting a substantial burden on the affected individual, their families, and healthcare systems globally. Deficits in autobiographical memory have been identified among individuals living with chronic pain, and even found to pose a risk for the transition to chronicity. Recent neuroimaging studies have simultaneously implicated common brain regions central to autobiographical memory processing in the maintenance of and susceptibility to chronic pain. The present review proposes a novel neurocognitive framework for chronic pain explained by mechanisms underlying the autobiographical memory system. Here, we 1) summarize the current literature on autobiographical memory in pain, 2) discuss the role of the hippocampus and cortical brain regions including the ventromedial prefrontal cortex, anterior temporal lobe, and amygdala in relation to autobiographical memory, memory schemas, emotional processing, and pain, 3) synthesize these findings in a neurocognitive framework that explains these relationships and their implications for patients' pain outcomes, and 4) propose translational directions for the prevention, management, and treatment of chronic pain.

Mapping pathways to neuronal atrophy in healthy, mid-aged adults: From chronic stress to systemic inflammation to neurodegeneration?

Growing evidence implicates systemic inflammation in the loss of structural brain integrity in natural ageing and disorder development. Chronic stress and glucocorticoid exposure can potentiate inflammatory processes and may also be linked to neuronal atrophy, particularly in the hippocampus and the human neocortex. To improve understanding of emerging maladaptive interactions between stress and inflammation, this study examined evidence for glucocorticoid- and inflammation-mediated neurodegeneration in healthy mid-aged adults. N = 169 healthy adults (mean age = 39.4, 64.5% female) were sampled from the general population in the context of the ReSource Project. Stress, inflammation and neuronal atrophy were quantified using physiological indices of chronic stress (hair cortisol (HCC) and cortisone (HEC) concentration), systemic inflammation (interleukin-6 (IL-6), high-sensitive C-reactive protein (hs-CRP)), the systemic inflammation index (SII), hippocampal volume (HCV) and cortical thickness (CT) in regions of interest. Structural equation models were used to examine evidence for pathways from stress and inflammation to neuronal atrophy. Model fit indices indicated good representation of stress, inflammation, and neurological data through the constructed models (CT model: robust RMSEA = 0.041, robust χ2 = 910.90; HCV model: robust RMSEA <0.001, robust χ2 = 40.95). Among inflammatory indices, only the SII was positively associated with hair cortisol as one indicator of chronic stress (β = 0.18, p < 0.05). Direct and indirect pathways from chronic stress and systemic inflammation to cortical thickness or hippocampal volume were non-significant. In exploratory analysis, the SII was inversely related to mean cortical thickness. Our results emphasize the importance of considering the multidimensionality of systemic inflammation and chronic stress, with various indicators that may represent different aspects of the systemic reaction. We conclude that inflammation and glucocorticoid-mediated neurodegeneration indicated by IL-6 and hs-CRP and HCC and HEC may only emerge during advanced ageing and disorder processes, still the SII could be a promising candidate for detecting associations between inflammation and neurodegeneration in younger and healthy samples. Future work should examine these pathways in prospective longitudinal designs, for which the present investigation serves as a baseline.

Consistently increased dorsolateral prefrontal cortex activity during the exposure to acute stressors

Stress has a major impact on our mental health. Nonetheless, it is still not fully understood how the human brain responds to ongoing stressful events. Here, we aimed to determine the cortical dynamics during the exposure to ecologically valid, standardized stressors. To this end, we conducted 3 experiments in which healthy participants underwent the Trier Social Stress Test (experiments 1 and 2) and the Socially Evaluated Cold Pressor Test (experiment 3) or a respective control manipulation, while we measured their cortical activity using functional near-infrared spectroscopy. Increases in salivary cortisol and subjective stress levels confirmed the successful stress induction in all experiments. Results of experiment 1 showed significantly increased cortical activity, in particular in the dorsolateral prefrontal cortex, during the exposure to the Trier Social Stress Test. Experiment 2 replicated this finding and showed further that this stress-related increase in dorsolateral prefrontal cortex activity was transient and limited to the period of the Trier Social Stress Test. Experiment 3 demonstrated the increased dorsolateral prefrontal cortex activity during the Socially Evaluated Cold Pressor Test, suggesting that this increase is generalizable and not specific to the Trier Social Stress Test. Together, these data show consistently that dorsolateral prefrontal cortex activity is not reduced, as commonly assumed, but increased under stress, which may promote coping with the ongoing stressor.

Neuroendocrine and cellular mechanisms in stress resilience: From hormonal influence in the CNS to mitochondrial dysfunction and oxidative stress

Recent advancements in neuroendocrinology challenge the long-held belief that hormonal effects are confined to perivascular tissues and do not extend to the central nervous system (CNS). This paradigm shift, propelled by groundbreaking research, reveals that synthetic hormones, notably in anti-inflammatory medications, significantly influence steroid psychosis, behavioural, and cognitive impairments, as well as neuropeptide functions. A seminal development in this field occurred in 1968 with McEven's proposal that rodent brains are responsive to glucocorticoids, fundamentally altering the understanding of how anxiety impacts CNS functionality and leading to the identification of glucocorticosteroids and mineralocorticoids as distinct corticotropic receptors. This paper focuses on the intricate roles of the neuroendocrine, immunological, and CNS in fostering stress resilience, underscored by recent animal model studies. These studies highlight active, compensatory, and passive strategies for resilience, supporting the concept that anxiety and depression are systemic disorders involving dysregulation across both peripheral and central systems. Resilience is conceptualized as a multifaceted process that enhances psychological adaptability to stress through adaptive mechanisms within the immunological system, brain, hypothalamo-pituitary-adrenal axis, and ANS Axis. Furthermore, the paper explores oxidative stress, particularly its origin from the production of reactive oxygen species (ROS) in mitochondria. The mitochondria's role extends beyond ATP production, encompassing lipid, heme, purine, and steroidogenesis synthesis. ROS-induced damage to biomolecules can lead to significant mitochondrial dysfunction and cell apoptosis, emphasizing the critical nature of mitochondrial health in overall cellular function and stress resilience. This comprehensive synthesis of neuroendocrinological and cellular biological research offers new insights into the systemic complexity of stress-related disorders and the imperative for multidisciplinary approaches in their study and treatment.

Astrocyte-derived lactate in stress disorders

Stress disorders are psychiatric disorders arising following stressful or traumatic events. They could deleteriously affect an individual's health because they often co-occur with mental illnesses. Considerable attention has been focused on neurons when considering the neurobiology of stress disorders. However, like other mental health conditions, recent studies have highlighted the importance of astrocytes in the pathophysiology of stress-related disorders. In addition to their structural and homeostatic support role, astrocytes actively serve several functions in regulating synaptic transmission and plasticity, protecting neurons from toxic compounds, and providing metabolic support for neurons. The astrocyte-neuron lactate shuttle model sets forth the importance of astrocytes in providing lactate for the metabolic supply of neurons under intense activity. Lactate also plays a role as a signaling molecule and has been recently studied regarding its antidepressant activity. This review discusses the involvement of astrocytes and brain energy metabolism in stress and further reflects on the importance of lactate as an energy supply in the brain and its emerging antidepressant role in stress-related disorders.

Neural association between cognitive function and anhedonia in adolescents with melancholic major depressive disorder: A fNIRS study

BACKGROUND

Cognitive dysfunction is common among adolescent patients with major depressive disorder (MDD). However, the pattern and magnitude of cognition impairment in patients during melancholic episodes remains unclear. The purpose of this study was to compare the neurocognitive performance and the underlying cerebral blood flow activation of adolescent patients with melancholic and non-melancholic features.

METHODS

Fifty-seven and 44 adolescent patients with MDD with or without melancholic feature (MDD-MEL/nMEL) and 58 healthy controls (HCs) were recruited. We used the repeatable battery for the assessment of neuropsychological status (RBANS) measuring neurocognitive function, and used functional near infrared spectroscopy (fNIRS) monitoring cerebral hemodynamic changes, described by β value. The non-parametric test and post-hoc analysis were conducted in RBANS scores and β values among three groups. Spearman correlation and mediating analysis was performed for RBANS scores, β values, and clinical symptoms in the MDD-MEL group.

RESULTS

There were no significant difference in RBANS scores between MDD-MEL and MDD-nMEL group. Compared with patients in MDD-nMEL, patients in MDD-MEL have lower β values in eight channels (ch10, ch16, ch20, ch25, ch27, ch37, ch41, ch45). The cognitive function is significantly correlated with anhedonia, and the β values play a partial mediating role between anhedonia and cognitive function.

LIMITATION

It's a cross-sectional study and monitoring longitudinal effects are needed to further elucidate the mechanism.

CONCLUSION

The cognitive function in adolescents with MDD-MEL may not significantly differ from those with MDD-nMEL. However, the anhedonia may influenced the cognitive function by altering the function of medial frontal cortex.

Homocysteine Modulates Social Isolation-Induced Depressive-Like Behaviors Through BDNF in Aged Mice

Social isolation is an unpleasant experience associated with an increased risk of mental disorders. Exploring whether these experiences affect behaviors in aged people is particularly important, as the elderly is very likely to suffer from periods of social isolation during their late-life. In this study, we analyzed the depressive-like behaviors, plasma concentrations of homocysteine (Hcy), and brain-derived neurotropic factor (BDNF) levels in aged mice undergoing social isolation. Results showed that depressive-like behavioral performance and decreased BDNF level were correlated with increased Hcy levels that were detected in 2-month isolated mice. Elevated Hcy induced by high methionine diet mimicked the depressive-like behaviors and BDNF downregulation in the same manner as social isolation, while administration of vitamin B complex supplements to reduce Hcy alleviated the depressive-like behaviors and BDNF reduction in socially isolated mice. Altogether, our results indicated that Hcy played a critical role in social isolation-induced depressive-like behaviors and BDNF reduction, suggesting the possibility of Hcy as a potential therapeutic target and vitamin B intake as a potential value in the prevention of stress-induced depression.

Prospective Effects of Discrimination, Depressive Symptoms, and Cognitive Control Among Mexican-Origin Women

OBJECTIVES

Cognitive control predicts functional independence and cognitive health outcomes, but is yet to be known the extent to which social stress, like discrimination, may diminish cognitive control capacities in Mexican-origin women. We evaluated the prospective associations between everyday and ethnic discrimination on cognitive control and examined the mediating effects of depressive symptoms on these links. We further examined the extent to which associations varied by age and financial strain.

METHODS

We used data from 596 Mexican-origin women (average age = 38.89, standard deviation = 5.74) who participated in a 3-wave longitudinal study spanning 8 years (from 2012 to 2020). Participants completed measures of everyday and ethnic discrimination at Wave 1, depressive symptoms in Waves 1 and 2, and completed computer-based tasks of cognitive control at Wave 3. Self-reported assessments of financial strain were completed at Wave 2. Moderated mediation structural equation models were implemented to test hypotheses.

RESULTS

Depressive symptoms significantly mediated the prospective association between everyday/ethnic discrimination to cognitive control. Higher levels of everyday and ethnic discrimination at baseline were associated with more depressive symptoms at Wave 2, which were then related to poorer cognitive control (i.e., longer reaction time in congruent and/or incongruent trials) at Wave 3. There was no significant moderation of age. Among those with low financial strain, higher levels of everyday discrimination were related to faster response times.

DISCUSSION

Results revealed the long-term consequences of experiences with discrimination on cognitive control that operate through increased depressive symptoms and that may have some subtle differential effects across levels of financial strain.

Glucocorticoid-Responsive Tissue Plasminogen Activator (tPA) and Its Inhibitor Plasminogen Activator Inhibitor-1 (PAI-1): Relevance in Stress-Related Psychiatric Disorders

Stressful events trigger a set of complex biological responses which follow a bell-shaped pattern. Low-stress conditions have been shown to elicit beneficial effects, notably on synaptic plasticity together with an increase in cognitive processes. In contrast, overly intense stress can have deleterious behavioral effects leading to several stress-related pathologies such as anxiety, depression, substance use, obsessive-compulsive and stressor- and trauma-related disorders (e.g., post-traumatic stress disorder or PTSD in the case of traumatic events). Over a number of years, we have demonstrated that in response to stress, glucocorticoid hormones (GCs) in the hippocampus mediate a molecular shift in the balance between the expression of the tissue plasminogen activator (tPA) and its own inhibitor plasminogen activator inhibitor-1 (PAI-1) proteins. Interestingly, a shift in favor of PAI-1 was responsible for PTSD-like memory induction. In this review, after describing the biological system involving GCs, we highlight the key role of tPA/PAI-1 imbalance observed in preclinical and clinical studies associated with the emergence of stress-related pathological conditions. Thus, tPA/PAI-1 protein levels could be predictive biomarkers of the subsequent onset of stress-related disorders, and pharmacological modulation of their activity could be a potential new therapeutic approach for these debilitating conditions.

Functional near-infrared spectroscopy is a sensitive marker of neurophysiological deficits on executive function tasks in young adults with a history of child abuse

Previous research has shown the utility of imaging measures of neural activity in identifying deficits in cognitive functioning in individuals with a history of child abuse. The purpose of the present study was to measure differences that may exist between individuals who reported physical, emotional, or sexual abuse as children (n = 37) vs. those who did not (n = 47) using Functional Near Infrared Spectroscopy (fNIRS) during the completion of cognitive tasks of executive function. The results showed a significantly higher rate and number of errors of commission on the Conners CPT test in the child abuse group compared to the control group. The analyses also showed a statistically significant decrease in oxyhemoglobin (oxy-Hb) concentration in the left rostral prefrontal cortex in the child abuse group compared to the no-abuse group during the Wisconsin Card Sorting Test (WCST). A similar, albeit non-significant, trend toward decreased oxy-Hb concentration was observed in the child abuse group in the right dorsolateral prefrontal cortex (dlPFC) on the OSPAN and Connors CPT. The results suggest that the latter group may show subtle neurological deficits that persist into adulthood that may not manifest on traditional measures of cognitive function. These findings have implications for the development of remediation and treatment strategies in this population.

Effects of intra-hippocampal corticosterone and sleep on consolidation of memories of aversive experience in rats

Formation and consolidation of memories for highly stressful (traumatic) events is a complex process that involves interplay between multiple memory systems and has implications for etiology and treatment of stress- and trauma-related disorders. Here we study effects of sleep/wake states and high intra-hippocampal corticosterone on consolidation of aversive contextual memories, as well as consolidation of association between auditory unpaired phasic background cues and fear response in rats. Animals were implanted with EEG and EMG electrodes for sleep assessment and cannulas for intra-hippocampal corticosterone application. They were familiarized to a "safe box" and then trained in a fear conditioning paradigm in a distinct "shock box" with a prominent unpaired phasic background auditory cue. Immediately after conditioning, animals received bilateral intra-hippocampal saline (1 μl) or corticosterone (10 ng in 1 μl) injection and were either allowed to sleep or were kept awake for a following two-hour consolidation period. Memory tests 24 h later revealed that the saline-injected animals that slept during consolidation had significantly stronger fear responses in the shock box compared to the safe box as well as increased fear response in response to the auditory cue. Lack of sleep during the consolidation period in saline injected animals led to generalization of the fear response to the safe context, while association between auditory cue and fear response was preserved. High intra-hippocampal corticosterone levels during memory consolidation led to generalization of fear response to the safe context, regardless of sleep/wake state, while enhancement of response to auditory cue was not observed. Our results show how manipulation of conditions during consolidation can lead to greatly variable memories for an aversive episode with distinct behavioral outcomes. Observed overgeneralization of fear to safe context and altered fear response to background phasic cue has implications for understanding etiology of pathological memory alternations in stress-related conditions e.g., in posttraumatic stress disorder in humans.

Stress disrupts insight-driven mnemonic reconfiguration in the medial temporal lobe

Memories are not stored in isolation. Insight into the relationship of initially unrelated events may trigger a flexible reconfiguration of the mnemonic representation of these events. Such representational changes allow the integration of events into coherent episodes and help to build up-to-date-models of the world around us. This process is, however, frequently impaired in stress-related mental disorders resulting in symptoms such as fragmented memories in PTSD. Here, we combined a real life-like narrative-insight task, in which participants learned how initially separate events are linked, with fMRI-based representational similarity analysis to test if and how acute stress interferes with the insight-driven reconfiguration of memories. Our results showed that stress reduced the activity of medial temporal and prefrontal areas when participants gained insight into the link between events. Moreover, stress abolished the insight-related increase in representational dissimilarity for linked events in the anterior part of the hippocampus as well as its association with measures of subsequent memory that we observed in non-stressed controls. However, memory performance, as assessed in a forced-choice recognition test, was even enhanced in the stress group. Our findings suggest that acute stress impedes the neural integration of events into coherent episodes but promotes long-term memory for these integrated narratives and may thus have implications for understanding memory distortions in stress-related mental disorders.

Neural correlates linking trauma and physical symptoms

Trauma and chronic pain frequently co-occur, but the underlying neurological mechanisms are poorly understood. The current study investigated the neural correlates of stress and physical symptoms in trauma patients using functional magnetic resonance imaging (fMRI) and follow-up smartphone surveys. Participants were 10 patients diagnosed with Trauma- and Stressor-Related Disorders and 18 demographically-matched healthy controls who completed a fMRI stress provocation task in which they viewed stressful and neutral-relaxing images. Subsequently, participants completed daily smartphone surveys which prospectively monitored their stress and physical symptoms for 30 days. The trauma group experienced a significantly higher frequency of physical symptoms than controls during the follow-up period. During stress, trauma patients exhibited increased activity in the hippocampus, insula, and sensorimotor areas, but decreased activity in the ventromedial prefrontal cortex (vmPFC), lateral prefrontal cortex (LPFC), and dorsal striatum relative to controls. In all participants, higher physical symptom frequency was significantly associated with a hyperactive left hippocampal response to stress. The current study reports that trauma is characterized by greater physical symptoms and decreased prefrontal but increased limbic responses to stress. Our findings suggest that trauma may increase physical health symptoms by compromising hippocampal function, which could also increase vulnerability to stress- and pain-related disorders.

Doll Therapy Intervention Reduces Challenging Behaviours of Women with Dementia Living in Nursing Homes: Results from a Randomized Single-Blind Controlled Trial

Background: Doll therapy (DT) is a non-pharmacological intervention for the treatment of the behavioural and psychological symptoms of dementia (BPSD). We designed a single-blind randomized controlled trial of the 30-day efficacy of DT in reducing the BPSD, professional caregivers’ distress and patients’ biomarkers of stress, and in improving the exploration and caregiving behaviours. Methods: We randomly assigned 134 women with moderate-to-severe dementia living in nursing homes (NHs) to a DT intervention (DTI, 67) or a sham intervention with a cube (SI, 67). Results: From the first to the 30th session, the DTI group showed a significant decrease in the Neuropsychiatric Inventory-NH (NPI-NH) total score and in the NPI-NH-Distress score compared to the SI group (both p < 0.001). We observed a greater interest in the doll than in the cube, a greater acceptance of a separation from the nurse among DTI participants, and caregiving and exploratory behaviours towards the doll. There were no differences between the groups in the stress biomarkers. Conclusions: Consistent with attachment theory, our findings support the 30-day efficacy of DT, as this non-pharmacological intervention promotes perceptions of security by creating a situation in which patients feel confident and engaged in a caregiving relationship with the doll and reduces the challenging behaviours that are stressful for professional caregivers.

The increased cortisol levels with preserved rhythmicity in aging and its relationship with dementia and metabolic syndrome

BACKGROUND

In the aging process, the cumulative exposure to stress with increased cortisol levels is considered to be associated to the senescence itself and its related disorders.

AIMS

To evaluate the role of cortisol in elderly subjects, with or without dementia, by the means of the AGICO study.

METHODS

The AGICO study enrolled patients from ten Geriatric Units in Italy in 2012-2017 (Study Director Prof Paolo Falaschi, S. Andrea Hospital of Rome). Every subject received a comprehensive geriatric assessment (including the Mini-Mental State Examination, MMSE), the neurological examination (with a computed tomography scan or magnetic resonance imaging of the brain), the assessment of the metabolic syndrome (MetS), the evaluation of the cortisol activity by two consecutive urine collections (diurnal and nocturnal).

RESULTS

The MMSE was inversely related to the standardized diurnal and nocturnal urinary cortisol levels (p < 0.025 and p < 0.01, respectively) and the age was positively related (p < 0.01 and p < 0.001, respectively). The ratio between the standardized diurnal and nocturnal urinary cortisol levels was 1.50 ± 1.2 (mean ± standard deviation) and it was not modified by the age or dementia. The standardized diurnal and nocturnal urinary cortisol levels were significantly higher in patients with dementia (MMSE < 24) (p < 0.01). In the analysis of the subgroups with MetS, the highest concentrations of diurnal and nocturnal cortisol were found in patients with both dementia and MetS (p < 0.025 and p < 0.01, respectively).

DISCUSSION

The AGICO study showed that the stress response significantly and progressively increases with age.

CONCLUSION

The cortisol increase in aging is related to the presence of both dementia and metabolic syndrome.

Relations among CRFR1 and FKBP5 genotype, cortisol, and cognitive function in aging humans: A Project FRONTIER study

Here we use the glucocorticoid cascade hypothesis framework to address the role of baseline cortisol on changes in cognitive function over a 3-year span in non-demented rural Americans. We also determine if genotype at 4 different single nucleotide polymorphisms (SNPs) relates to change in cognitive function. We predicted 1) over time, increases in baseline cortisol will be associated with decline in cognitive function, 2) individuals homozygous for 3 CRFR1 SNP rare alleles (AA rs110402, TT rs7209436, and TT rs242924 vs. others) will show less cognitive decline and this will be particularly pronounced in those with lower baseline cortisol, and 3) FKBP5 T carriers (TT or CT vs. CC homozygotes) will have decreased cognitive performance and this will be particularly pronounced in individuals with higher baseline cortisol. Collectively, our data do not robustly support the glucocorticoid cascade hypothesis. In several cases, higher baseline cortisol related to better cognitive performance over time, but within individuals, increased cortisol over time related to decreased performance on some cognitive domains over time. Contrary to our predictions, individuals with the rare CRFR1 haplotype (AA, TT, TT) performed worse than individuals with the common haplotype across multiple domains of cognitive function. FKBP5 genotype status had minimal impacts on cognitive outcomes. Genotype effects were largely not dependent on cortisol. The Project FRONTIER dataset is supported by Texas Tech University Health Sciences Center Garrison Institute on Aging.

Changes in Stereotypies: Effects over Time and over Generations

Simple Summary

Herein, we propose that there should be discussion about the function and effects of stereotypies in relation to the time during which they are shown. In the first stages, stereotypies may help animals deal with challenges. However, behavior can potentially alter the brain, impairing its function due the absence of a diverse repertory, and change brain connections, neurophysiology and later neuroanatomy. The neuroanatomical changes in individuals showing stereotypies could be an effect rather than a cause of the stereotypy. As a consequence, studies showing different outcomes for animal welfare from stereotypy expression could be due to variation in a timeline of expression. Stereotypies are widely used as an animal welfare indicator, and their expression can tell us about psychological states. However, there are questions about the longer-term consequences if animals express stereotypies: do the stereotypies help in coping? During the prenatal period, stereotypic behavior expressed by the mother can change the phenotype of the offspring, especially regarding emotionality, one mechanism acting via methylation in the limbic system in the brain. Are individuals that show stereotypies for shorter or longer periods all better adjusted, and hence have better welfare, or is the later welfare of some worse than that of individuals that do not show the behavior?

Abstract

Stereotypies comprise a wide range of repeated and apparently functionless behaviors that develop in individuals whose neural condition or environment results in poor welfare. While stereotypies are an indicator of poor welfare at the time of occurrence, they may have various consequences. Environmental enrichment modifies causal factors and reduces the occurrence of stereotypies, providing evidence that stereotypies are an indicator of poor welfare. However, stereotypy occurrence and consequences change over time. Furthermore, there are complex direct and epigenetic effects when mother mammals that are kept in negative conditions do or do not show stereotypies. It is proposed that, when trying to deal with challenging situations, stereotypies might initially help animals to cope. After further time in the conditions, the performance of the stereotypy may impair brain function and change brain connections, neurophysiology and eventually neuroanatomy. It is possible that reported neuroanatomical changes are an effect of the stereotypy rather than a cause.

Diabetes and associated cognitive disorders: Role of the Hypothalamic-Pituitary Adrenal axis

Both diabetes types, types 1 and 2, are associated with cognitive impairments. Each period of life is concerned, and this is an increasing public health problem. Animal models have been developed to investigate the biological actors involved in such impairments. Many levels of the brain function (structure, volume, neurogenesis, neurotransmission, behavior) are involved. In this review, we detailed the part potentially played by the Hypothalamic-Pituitary Adrenal axis in these dysfunctions. Notably, regulating glucocorticoid levels, their receptors and their bioavailability appear to be relevant for future research studies, and treatment development.

Longitudinal Changes in Hearing and Visual Impairments and Risk of Dementia in Older Adults in the United States

IMPORTANCE

Hearing and vision problems are individually associated with increased dementia risk, but the impact of having concurrent hearing and vision deficits, ie, dual sensory impairment (DSI), on risk of dementia, including its major subtypes Alzheimer disease (AD) and vascular dementia (VaD), is not well known.

OBJECTIVE

To evaluate whether DSI is associated with incident dementia in older adults.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study from the Cardiovascular Health Study (CHS) was conducted between 1992 and 1999, with as many as 8 years of follow-up. The multicenter, population-based sample was recruited from Medicare eligibility files in 4 US communities with academic medical centers. Of 5888 participants aged 65 years and older in CHS, 3602 underwent cranial magnetic resonance imaging and completed the modified Mini-Mental State Examination in 1992 to 1994 as part of the CHS Cognition Study. A total of 227 participants were excluded due to prevalent dementia, leaving a total of 3375 participants without dementia at study baseline. The study hypothesis was that DSI would be associated with increased risk of dementia compared with no sensory impairment. The association between the duration of DSI with risk of dementia was also evaluated. Data analysis was conducted from November 2019 to February 2020.

EXPOSURES

Hearing and vision impairments were collected via self-report at baseline and as many as 5 follow-up visits.

MAIN OUTCOMES AND MEASURES

All-cause dementia, AD, and VaD, classified by a multidisciplinary committee using standardized criteria.

RESULTS

A total of 2927 participants with information on hearing and vision at all available study visits were included in the analysis (mean [SD] age, 74.6 [4.8] years; 1704 [58.2%] women; 455 [15.5%] African American or Black; 2472 [85.5%] White). Compared with no sensory impairment, DSI was associated with increased risk of all-cause dementia (hazard ratio [HR], 2.60; 95% CI, 1.66-2.06; P < .001), AD (HR, 3.67; 95% CI, 2.04-6.60; P < .001) but not VaD (HR, 2.03; 95% CI, 1.00-4.09; P = .05).

CONCLUSIONS AND RELEVANCE

In this cohort study, DSI was associated with increased risk of dementia, particularly AD. Evaluation of hearing and vision in older adults may help to identify those at high risk of developing dementia.

Combined Vision and Hearing Impairment is Associated with Frailty in Older Adults: Results from the West China Health and Aging Trend Study

Objective

Hearing and vision loss have been independently associated with frailty in older adults, but the relationship between concurrent hearing and visual impairment (dual sensory impairment) and frailty is not well understood. Therefore, we aimed to examine whether dual sensory impairment is associated with frailty in older adults.

Methods

This cross-sectional study was based on the data from the West China Health and Aging Trend (WCHAT) study of community-dwelling individuals aged 60 years and older. Frailty status was evaluated by the FRAIL scale and categorized as robust, prefrail and frail. Hearing and vision functions were based on self-report. We used multinomial regression models to explore the association between dual sensory impairment and frailty.

Results

Of 3985 participants, 1655 (41.5%) were male and the median age was 66 years (interquartile range: 61–68). Overall, 7.6% of participants reported hearing impairment only, 32.7% reported vision impairment only, and 28.6% reported dual sensory impairment. The prevalence of prefrailty and frailty was 60.7% and 6.1%, respectively. After adjustment for confounding variables, results from the multinomial regression analysis showed that dual sensory impairment was significantly associated with greater odds of becoming frail (OR = 2.17, 95% CI = 1.40–3.38) compared with no impairment. When stratified by gender, dual sensory impairment was significantly associated with frailty in women (OR = 2.42, 95% CI = 1.40–4.20) but not in men (OR = 1.30, 95% CI = 0.58–2.91).

Conclusion

Older adults with dual sensory impairment are more likely to be frail than those with no impairment, suggesting that interventions to improve sensory function may potentially help reduce the risk of frailty in older adults.

Language matters: humanizing service robots through the use of language during the COVID-19 pandemic

Service robots are emerging quickly in the marketplace (e.g., in hotels, restaurants, and healthcare), especially as COVID-19-related health concerns and social distancing guidelines have affected people's desire and ability to interact with other humans. However, while robots can increase efficiency and enable service offerings with reduced human contact, prior research shows a systematic consumer aversion toward service robots relative to human service providers. This potential dilemma raises the managerial question of how firms can overcome consumer aversion and better employ service robots. Drawing on prior research that supports the use of language for building interpersonal relationships, this research examines whether the type of language (social-oriented vs. task-oriented language) a service robot uses can improve consumer responses to and evaluations of the focal service robot, particularly in light of consumers' COVID-19-related stress. The results show that consumers respond more favorably to a service robot that uses a social-oriented (vs. task-oriented) language style, particularly when these consumers experience relatively higher levels of COVID-19-related stress. These findings contribute to initial empirical evidence in marketing for the efficacy of leveraging robots' language style to improve customer evaluations of service robots, especially under stressful circumstances. Overall, the results from two experimental studies not only point to actionable managerial implications but also to a new avenue of research on service robots that examines customer-robot interactions through the lens of language and in contexts that can be stressful for consumers (e.g., healthcare or some financial service settings).

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11002-022-09630-x.

Homocysteine-Induced Disturbances in DNA Methylation Contribute to Development of Stress-Associated Cognitive Decline in Rats

Chronic stress is generally accepted as the main risk factor in the development of cognitive decline; however, the underlying mechanisms remain unclear. Previous data have demonstrated that the levels of homocysteine (Hcy) are significantly elevated in the plasma of stressed animals, which suggests that Hcy is associated with stress and cognitive decline. To test this hypothesis, we analyzed the cognitive function, plasma concentrations of Hcy, and brain-derived neurotropic factor (BDNF) levels in rats undergoing chronic unpredicted mild stress (CUMS). The results showed that decreased cognitive behavioral performance and decreased BDNF transcription and protein expression were correlated with hyperhomocysteinemia (HHcy) levels in stressed rats. Diet-induced HHcy mimicked the cognitive decline and BDNF downregulation in the same manner as CUMS, while Hcy reduction (by means of vitamin B complex supplements) alleviated the cognitive deficits and BDNF reduction in CUMS rats. Furthermore, we also found that both stress and HHcy disturbed the DNA methylation process in the brain and induced DNA hypermethylation in the BDNF promoter. In contrast, control of Hcy blocked BDNF promoter methylation and upregulated BDNF levels in the brain. These results imply the possibility of a causal role of Hcy in stress-induced cognitive decline. We also used ten-eleven translocation (TET1), an enzyme that induces DNA demethylation, to verify the involvement of Hcy and DNA methylation in the regulation of BDNF expression and the development of stress-related cognitive decline. The data showed that TET1-expressing viral injection into the hippocampus inhibited BDNF promoter methylation and significantly mitigated the cognitive decline in HHcy rats. Taken together, novel evidence from the present study suggests that Hcy is likely involved in chronic stress-induced BDNF reduction and related cognitive deficits. In addition, the negative side-effects of HHcy may be associated with Hcy-induced DNA hypermethylation in the BDNF promoter. The results also suggest the possibility of Hcy as a target for therapy and the potential value of vitamin B intake in preventing stress-induced cognitive decline.

The magnitude and effect of work-life imbalance on cognition and affective range among the non-western population: A study from Muscat

The temporal relationship between work-life balance/imbalance, occupational burnout, and poor mental health outcomes have been widely explored. Little has been forthcoming on cognitive functioning among those with work-life imbalance. This study aimed to explore the rate of work-life imbalance and the variation in neuropsychological functioning. The relationship between affective ranges (anxiety and depressive symptoms) and work-life balance was also explored. The target population in this study are Omani nationals who were referred for psychometric evaluation. The study employs neuropsychology measures tapping into attention and concentration, learning and remembering, processing speed, and executive functioning. Subjective measures of cognitive decline and affective ranges were also explored. A total of 168 subjects (75.3% of the responders) were considered to be at a work-life imbalance. Multivariate analysis showed that demographic and neuropsychological variables were significant risk factors for work-life imbalance including age and the presence of anxiety disorder. Furthermore, participants indicating work-life imbalance were more likely to report cognitive decline on indices of attention, concentration, learning, and remembering. This study reveals that individuals with work-life imbalance might dent the integrity of cognition including attention and concentration, learning and remembering, executive functioning, and endorsed case-ness for anxiety.

Chronobiology of transient global amnesia

INTRODUCTION

The etiology of transient global amnesia (TGA) is still a matter of debate. Based, among others, on the observation of a close temporal relation between certain events and subsequent TGA episodes, recent proposals discuss the relevance of stress-associated processes impacting on hippocampal functioning. Circadian, infra- and ultradian rhythmicity has been found to play a relevant role in the multifactorial pathomechanisms of various disorders but has not been thoroughly studied in TGA.

METHODS

Data of patients with a final diagnosis of TGA were collected in Mannheim, Germany (06/1999-01/2018, n = 404), and in the Kansai district, Japan (04/2006-03/2018, n = 261). Chronological patterns of TGA occurrence were determined.

RESULTS

Significant circadian rhythmicity of TGA occurrence with bimodal peaks (mid-morning, late afternoon) was found for the entire population (p = 0.002) and for either sub-cohort (Mannheim: p = 0.003, Kansai: p = 0.007). This finding was confirmed for either sex (women: p = 0.004, men: p = 0.004) and different age groups (< 65 years: p = 0.0009, ≥ 65 years: p = 0.003). There was no variation according to day of the week, month or season, but the proportion of patients with a weekday episode was significantly higher in the Mannheim cohort (p = 0.002).

DISCUSSION

We identified a robust circadian rhythm in TGA occurrence which remarkably applied to either of the two study sites located on different continents and which was independent of sex and age. In light of abundant evidence of circadian rhythmicity of both, components of the human stress response system and memory, chronobiological analyses may provide an opportunity to further uncover the mechanisms underlying TGA.

Estrogenic signaling and sociosexual behavior in wild sex-changing bluehead wrasses, Thalassoma bifasciatum

Estrogenic signaling is an important focus in studies of gonadal and brain sexual differentiation in fishes and vertebrates generally. This study examined variation in estrogenic signaling (1) across three sexual phenotypes (female, female-mimic initial phase [IP] male, and terminal phase [TP] male), (2) during socially-controlled female-to-male sex change, and (3) during tidally-driven spawning cycles in the protogynous bluehead wrasse (Thalassoma bifasciatum). We analyzed relative abundances of messenger RNAs (mRNAs) for the brain form of aromatase (cyp19a1b) and the three nuclear estrogen receptors (ER) (ERα, ERβa, and ERβb) by qPCR. Consistent with previous reports, forebrain/midbrain cyp19a1b was highest in females, significantly lower in TP males, and lowest in IP males. By contrast, ERα and ERβb mRNA abundances were highest in TP males and increased during sex change. ERβa mRNA did not vary significantly. Across the tidally-driven spawning cycle, cyp19a1b abundances were higher in females than TP males. Interestingly, cyp19a1b levels were higher in TP males close (~1 h) to the daily spawning period when sexual and aggressive behaviors rise than males far from spawning (~10-12 h). Together with earlier findings, our results suggest alterations in neural estrogen signaling are key regulators of socially-controlled sex change and sexual phenotype differences. Additionally, these patterns suggest TP male-typical sociosexual behaviors may depend on intermediate rather than low estrogenic signaling. We discuss these results and the possibility that an inverted-U shaped relationship between neural estrogen and male-typical behaviors is more common than presently appreciated.

Involvement of Ghrelin Dynamics in Stress-Induced Eating Disorder: Effects of Sex and Aging

Stress, a factor that affects appetite in our daily lives, enhances or suppresses appetite and changes palatability. However, so far, the mechanisms underlying the link between stress and eating have not been fully elucidated. Among the peripherally produced appetite-related peptides, ghrelin is the only orexigenic peptide, and abnormalities in the dynamics and reactivity of this peptide are involved in appetite abnormalities in various diseases and psychological states. This review presents an overview of the research results of studies evaluating the effects of various stresses on appetite. The first half of this review describes the relationship between appetite and stress, and the second half describes the relationship between the appetite-promoting peptide ghrelin and stress. The effects of sex differences and aging under stress on appetite are also described.

Association of Stress with Risk of Dementia and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Although many studies have investigated the association between stress and risk of dementia, findings are inconsistent due to the variation in the measures used to assess stress.

OBJECTIVE

We conducted a systematic review and meta-analysis to investigate the association between psychological stress (including neuroticism, stressful life events, and perceived stress) and the risk of incident dementia and mild cognitive impairment in adults.

METHODS

PsycINFO, Embase, and MEDLINE were searched to October 2020 for eligible observational, prospective studies. Of the 1,607 studies screened, 26 (24 unique cohorts) were included in the qualitative analysis and 16 (15 unique cohorts) were included in the quantitative analysis.

RESULTS

Across studies, higher perceived stress was significantly associated with an increased risk of mild cognitive impairment (Cases/Total N = 207/860: hazard ratio [HR] = 1.19, 95% confidence interval [CI] = 1.03-1.38) and all-cause dementia (Cases/Total N = 203/1,882: HR = 1.44, 95% CI = 1.07-1.95). Exposure to two or more stressful life events (versus none) was significantly associated with an increased risk of all-cause dementia (Cases/Total N = 3,354/11,597: HR = 1.72, 95% CI = 1.14-2.60), while one or more stressful life events was not. Higher neuroticism was significantly associated with an increased risk of Alzheimer's disease dementia (Cases/Total N = 497/4,771: HR = 1.07, 95% CI = 1.01-1.12), but not all-cause dementia.

CONCLUSION

This review suggests that psychological stress in adulthood is associated with an increased risk of dementia. Further research is needed to clarify the mechanisms underlying these associations.

Stability of hippocampal subfield volumes after trauma and relationship to development of PTSD symptoms

BACKGROUND

The hippocampus plays a central role in post-traumatic stress disorder (PTSD) pathogenesis, and the majority of neuroimaging research on PTSD has studied the hippocampus in its entirety. Although extensive literature demonstrates changes in hippocampal volume are associated with PTSD, fewer studies have probed the relationship between symptoms and the hippocampus' functionally and structurally distinct subfields. We utilized data from a longitudinal study examining post-trauma outcomes to determine whether hippocampal subfield volumes change post-trauma and whether specific subfields are significantly associated with, or prospectively related to, PTSD symptom severity. As a secondary aim, we leveraged our unique study design sample to also investigate reliability of hippocampal subfield volumes using both cross-sectional and longitudinal pipelines available in FreeSurfer v6.0.

METHODS

Two-hundred and fifteen traumatically injured individuals were recruited from an urban Emergency Department. Two-weeks post-injury, participants underwent two consecutive days of neuroimaging (time 1: T1, and time 2: T2) with magnetic resonance imaging (MRI) and completed self-report assessments. Six-months later (time 3: T3), participants underwent an additional scan and were administered a structured interview assessing PTSD symptoms. First, we calculated reliability of hippocampal measurements at T1 and T2 (automatically segmented with FreeSurfer v6.0). We then examined the prospective (T1 subfields) and cross-sectional (T3 subfields) relationship between volumes and PTSD. Finally, we tested whether change in subfield volumes between T1 and T3 explained PTSD symptom variability.

RESULTS

After controlling for sex, age, and total brain volume, none of the subfield volumes (T1) were prospectively related to T3 PTSD symptoms nor were subfield volumes (T3) associated with current PTSD symptoms (T3). Tl - T2 reliability of all hippocampal subfields ranged from good to excellent (intraclass correlation coefficient (ICC) values > 0.83), with poorer reliability in the hippocampal fissure.

CONCLUSION

Our study was a novel examination of the prospective relationship between hippocampal subfield volumes in relation to PTSD in a large trauma-exposed urban sample. There was no significant relationship between subfield volumes and PTSD symptoms, however, we confirmed FreeSurfer v6.0 hippocampal subfield segmentation is reliable when applied to a traumatically-injured sample, using both cross-sectional and longitudinal analysis pipelines. Although hippocampal subfield volumes may be an important marker of individual variability in PTSD, findings are likely conditional on the timing of the measurements (e.g. acute or chronic post-trauma periods) and analysis strategy (e.g. cross-sectional or prospective).

Contributions of Emotion Regulation and Brain Structure and Function to Adolescent Internalizing Problems and Stress Vulnerability During the COVID-19 Pandemic: A Longitudinal Study

BACKGROUND

Adolescence is a period of increased vulnerability for internalizing problems, particularly following stressful life events. We examined how emotion regulation and brain structure and function were associated with internalizing problems during the COVID-19 pandemic and moderated the association between pandemic-related stressors and internalizing problems.

METHODS

Data are from a longitudinal sample (N = 145, age range, 10-15 years) strategically assessed at 3 crucial time points: before the COVID-19 pandemic, early during the stay-at-home order period, and again 6 months later. We examined associations of amygdala and hippocampal volume and amygdala activation during an emotional processing task before the pandemic, examined use of emotion regulation strategies before and during the pandemic, and examined pandemic-related stressors with internalizing problems.

RESULTS

Greater exposure to pandemic-related stressors was associated with higher internalizing problems both early and later in the COVID-19 pandemic. Youths who reported more frequent use of rumination before the pandemic and higher use of expressive suppression and lower use of cognitive reappraisal early in the pandemic had higher internalizing problems early in the pandemic. Higher left amygdala activation to neutral relative to fearful faces before the pandemic was associated with greater internalizing problems and a stronger link between pandemic-related stressors and internalizing problems early in the pandemic.

CONCLUSIONS

Stressors related to the COVID-19 pandemic are strongly associated with adolescent internalizing problems, as are individual differences in emotional reactivity and regulation and their underlying neural mechanisms. Interventions that reduce pandemic-related stressors and foster adaptive emotion regulation skills may protect against adolescent psychopathology during this period of heightened exposure to stress.

Circadian fluctuations in glucocorticoid level predict perceptual discrimination sensitivity

Slow neurobiological rhythms, such as the circadian secretion of glucocorticoid (GC) hormones, modulate a variety of body functions. Whether and how endocrine fluctuations also exert an influence on perceptual abilities is largely uncharted. Here, we show that phasic increases in GC availability prove beneficial to auditory discrimination. In an age-varying sample of N = 68 healthy human participants, we characterize the covariation of saliva cortisol with perceptual sensitivity in an auditory pitch discrimination task at five time points across the sleep-wake cycle. First, momentary saliva cortisol levels were captured well by the time relative to wake-up and overall sleep duration. Second, within individuals, higher cortisol levels just prior to behavioral testing predicted better pitch discrimination ability, expressed as a steepened psychometric curve. This effect of GCs held under a set of statistical controls. Our results pave the way for more in-depth studies on neuroendocrinological determinants of sensory encoding and perception.

Stress and the Brain: An Emerging Role for Selenium

The stress response is an important tool in an organism’s ability to properly respond to adverse environmental conditions in order to survive. Intense acute or chronic elevation of glucocorticoids, a class of stress hormone, can have deleterious neurological effects, however, including memory impairments and emotional disturbances. In recent years, the protective role of the antioxidant micronutrient selenium against the negative impact of externally applied stress has begun to come to light. In this review, we will discuss the effects of stress on the brain, with a focus on glucocorticoid action in the hippocampus and cerebral cortex, and emerging evidence of an ability of selenium to normalize neurological function in the context of various stress and glucocorticoid exposure paradigms in rodent models.

Lifelong impact of extreme stress on the human brain: Holocaust survivors study

Background

We aimed to assess the lifelong impact of extreme stress on people who survived the Holocaust. We hypothesised that the impact of extreme trauma is detectable even after more than 70 years of an often complicated and stressful post-war life.

Methods

Psychological testing was performed on 44 Holocaust survivors (HS; median age 81.5 years; 29 women; 26 HS were under the age of 12 years in 1945) and 31 control participants without a personal or family history of the Holocaust (control group (CG); median 80 years; 17 women). Magnetic resonance imaging (MRI) using the 3T Siemens Prisma scanner was performed on 29 HS (median 79 years; 18 women) and 21 CG participants (median 80 years; 11 women). The MRI-tested subgroup that had been younger than 12 years old in 1945 was composed of 20 HS (median 79 years; 17 women) and 21 CG (median 80 years; 11 women).

Results

HS experienced significantly higher frequency of depression symptoms, posttraumatic stress symptoms, and posttraumatic growth, and lower levels of well-being. The MRI shows a lifelong neurobiological effect of extreme stress. The areas with reduced grey matter correspond to the map of the impact of stress on the brain structure: insula, anterior cingulate, ventromedial cortex including the subgenual cingulate/orbitofrontal cortex, temporal pole, prefrontal cortex, and angular gyrus. HS showed good adjustment to post-war life conditions.

Psychological growth may contribute to compensation for the psychological and neurobiological consequences of extreme stress.

The reduction of GM was significantly expressed also in the subgroup of participants who survived the Holocaust during their childhood.

Conclusion

The lifelong psychological and neurobiological changes in people who survived extreme stress were identified more than 70 years after the Holocaust. Extreme stress in childhood and young adulthood has an irreversible lifelong impact on the brain.

Chronic Mild Unpredictable Stress and High-Fat Diet Given during Adolescence Impact Both Cognitive and Noncognitive Behaviors in Young Adult Mice

Stress and diet are intricately linked, and they often interact in a negative fashion. Increases in stress can lead to poor food choices; adolescence is a period that is often accompanied by increased levels of stress. Stress and poor dietary choices can affect learning and memory; it is important to understand their combined effects when occurring during crucial developmental periods. Here, we present evidence that chronic mild unpredictable stress (CMUS) and high-fat diet (HFD) impact both cognitive and noncognitive behaviors when assessed after four weeks of manipulation in four-week old mice. CMUS mice had increased anxiety in the open field test (OFT) (p = 0.01) and spent more time in the open arms of the elevated zero maze (EZM) (p < 0.01). HFD administration was shown to interact with CMUS to impair spatial memory in the Morris Water Maze (MWM) (p < 0.05). Stress and diet also led to disturbances in non-cognitive behaviors: CMUS led to significantly more burrowing (p < 0.05) and HFD administration led to the poorer nest construction (p < 0.05). These findings allow for researchers to assess how modifying lifestyle factors (including diet and stress) during adolescence can serve as a potential strategy to improve cognition in young adulthood.

Does Stress Trigger Seizures? Evidence from Experimental Models

This chapter describes the experimental evidence of stress modulation of epileptic seizures and the potential role of corticosteroids and neurosteroids in regulating stress-linked seizure vulnerability. Epilepsy is a chronic neurological disorder that is characterized by repeated seizures. There are many potential causes for epilepsy, including genetic predispositions, infections, brain injury, and neurotoxicity. Stress is a known precipitating factor for seizures in individuals suffering from epilepsy. Severe acute stress and persistent exposure to stress may increase susceptibility to seizures, thereby resulting in a higher frequency of seizures. This occurs through the stress-mediated release of cortisol, which has both excitatory and proconvulsant properties. Stress also causes the release of endogenous neurosteroids from central and adrenal sources. Neurosteroids such as allopregnanolone and THDOC, which are allosteric modulators of GABA-A receptors, are powerful anticonvulsants and neuroprotectants. Acute stress increases the release of neurosteroids, while chronic stress is associated with severe neurosteroid depletion and reduced inhibition in the brain. This diminished inhibition occurs largely as a result of neurosteroid deficiencies. Thus, exogenous administration of neurosteroids (neurosteroid replacement therapy) may offer neuroprotection in epilepsy. Synthetic neurosteroid could offer a rational approach to control neurosteroid-sensitive, stress-related epileptic seizures.

Stigma associated with parental depression or cancer: Impact on spouse and offspring's cortisol levels and socioemotional functioning

Stress associated with caring for a mentally ill spouse can adversely affect the health status of caregivers and their children. Adding to the stress of caregiving is the stigma often placed against spouses and children of people with mental illness. Contrary to mental illness, many physical disorders such as cancer may be less stigmatized (expect pulmonary cancer). In this study, we measured externalized and internalized stigma, as well as psychological (depressive symptoms and stressful life events) and physiological (basal salivary cortisol levels) markers of stress in 115 spouses and 154 children of parents suffering from major depressive disorder, cancer, or no illness (control group). The results show that spouses and children from families with parental depression present significantly more externalized stigma than spouses and children from families with parental cancer or no illness, although we find no group differences on internalized stigma. The analysis did not show a significant group difference either for spouses or their children on depressive symptomatology, although spouses from the parental depression group reported greater work/family stress. Finally, we found that although for both spouses children the awakening cortisol response was greater on weekdays than on weekend days, salivary cortisol levels did not differ between groups. Bayes factor calculated on the null result for cortisol levels was greater than 100, providing strong evidence for the null hypothesis H0. Altogether, these results suggest an impact of stigma toward mental health disorder on psychological markers of stress but no impact of stigma on physiological markers of stress. We suggest that these results may be due to the characteristics of the families who participated in the present study.

The Neural Processes Interlinking Social Isolation, Social Support, and Problem Alcohol Use

BACKGROUND

Subjective feeling of social isolation, as can be measured by perceived burdensomeness (PB), is a major risk factor for alcohol misuse. Heightened PB is associated with elevated stress response and diminished cognitive control, both of which contribute to problem drinking. Here, we sought to identify the neural substrates underlying the relationship between PB and alcohol misuse.

METHODS

We employed resting-state functional magnetic resonance imaging data collected from 61 problem drinkers to characterize the functional connectivity of the hypothalamus and ventral striatum (VS) in relation to PB. We specifically examined whether the connectivities of the hypothalamus and VS were differentially influenced by PB to produce contrasting effects on alcohol use. Finally, we evaluated how individual differences in social support modulate the inter-relationships of social isolation, neural connectivity, and the severity of problem drinking.

RESULTS

Whole-brain multiple regressions show a positive relationship between PB and hypothalamic connectivity with the hippocampus and an inverse pattern for VS connectivity with the middle frontal gyrus. Difference in strength between the 2 connectivities predicted the severity of problem drinking, suggesting an imbalance involving elevated hypothalamic and diminished prefrontal cortical modulation in socially isolated problem drinkers. A path analysis further revealed that the lack of social support was associated with a bias toward low prefrontal connectivity, which in turn increased PB and facilitated problem drinking.

CONCLUSIONS

Altered hypothalamus and VS connectivity may underlie problem drinking induced by social isolation. The current findings also highlight the important role of social support as a potential protective factor against alcohol misuse.

Unusual purchasing behavior during the early stages of the COVID-19 pandemic: The stimulus-organism-response approach

During the COVID-19 pandemic, unusual consumer behavior, such as hoarding toilet paper, was reported globally. We investigated this behavior when fears of consumer market disruptions started circulating, to capture human behavior in this unique situation. Based on the stimulus-organism-response (S-O-R) framework, we propose a structural model connecting exposure to online information sources (environmental stimuli) to two behavioral responses: unusual purchases and voluntary self-isolation. To test the proposed model, we collected data from 211 Finnish respondents via an online survey, and carried out analysis using PLS-SEM. We found a strong link between self-intention to self-isolate and intention to make unusual purchases, providing empirical evidence that the reported consumer behavior was directly linked to anticipated time spent in self-isolation. The results further revealed exposure to online information sources led to increased information overload and cyberchondria. Information overload was also a strong predictor of cyberchondria. Perceived severity of the situation and cyberchondria had significant impacts on people's intention to make unusual purchases and voluntarily self-isolate. Future research is needed to confirm the long-term effects of the pandemic on consumer and retail services.

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We investigate people's purchase and isolation behavior during the COVID19 pandemic.

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Information source exposure leads to information overload (IO) and cyberchondria.

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IO had a negative effect on perceived severity, whereas cyberchondria had a positive impact.

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Perceived severity (PS) positively affected intentions to self-isolate and unusual purchases.

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Purchase self-efficacy reinforces the influence of PS on unusual purchases.

The role of neighborhood stressors on cognitive function: A coordinated analysis

The objective of this study was to evaluate the association between perceived neighborhood stressors, encompassing negative perceived neighborhood characteristics, and specific cognitive abilities in adulthood. We conducted a coordinated analysis across three studies of adults in the United States and found that perceived neighborhood stressors were consistently associated with poorer performance on attention-demanding cognitive tasks. We specifically found that perceived neighborhood stressors were associated with lower performance in spatial abilities, working memory, and executive function but not perceptual speed, and that the effect was most consistent for lower perceived neighborhood safety followed by lower perceived aesthetic quality, greater perceived neighborhood crime, and lower perceived neighborhood cohesion. These results highlight the importance of the psychosocial neighborhood context for cognitive health in adulthood.

Changes in Cognitive Functions Following Violent and Football Video Games in Young Male Volunteers by Studying Brain Waves

Introduction:

This research investigated the effects of violent and football video games on cognitive functions, cortisol levels, and brain waves.

Methods:

A total of 64 participants competed in a single-elimination tournament. Saliva samples of all players were obtained before and after the games for the assessment of cortisol levels. The cognitive performances of the players were also assessed by paced auditory serial addition test. Moreover, the electroencephalogram recording was conducted during the games.

Results:

The results showed that salivary cortisol levels significantly decreased after playing both games. Also, playing the football game increased reaction time, whereas decreased sustained attention and mental fatigue.

Conclusion:

Conversely, following playing a violent game, the reaction time decreased, and sustained attention and mental fatigue increased. Furthermore, the results of the EEG recording revealed that playing a violent game engaged more brain regions than the football game. In conclusion, playing violent game more effectively improved cognitive performances in the players than the football game.

Association of Sensory Impairments With Cognitive Decline and Depression Among Older Adults in China

IMPORTANCE

Sensory impairments may heighten the risk of premature brain aging. Little is known regarding the association of sensory impairments with cognitive function and depression in China.

OBJECTIVE

To examine the association of visual and/or hearing impairments with cognitive decline and depression.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used the data from 18 038 respondents to the 2015 survey of the China Health and Retirement Longitudinal Study, a nationally representative survey of adults aged 45 years or older and their spouses.

EXPOSURES

The presence of sensory impairments was identified by self-reported assessment of visual and/or hearing functions.

MAIN OUTCOMES AND MEASURES

Overall, 3 composite measures were used to assess the respondents' cognitive performance, including episodic memory, mental intactness, and global cognitive function. Depression was examined using the 10-item Center for Epidemiological Studies-Depression scale score. Multiple generalized linear regression models, adjusting for self-reported sociodemographic characteristics, health behaviors, chronic conditions, and participants' overall health, were used.

RESULTS

Of 18 038 respondents, 9244 (51.2%) were women. The mean (SD) age was 59.9 (9.7) years. Respondents with visual impairment had poorer episodic memory (β = -0.12; 95% CI, -0.19 to -0.05) and global cognition (β = -0.16; 95% CI, -0.31 to -0.02) and a greater risk of depression (odds ratio, 1.78; 95% CI, 1.59 to 1.99) than those without visual impairment. Respondents with hearing impairment had poorer episodic memory (β = -0.24; 95% CI, -0.30 to -0.18), mental intactness (β = -0.19; 95% CI, -0.28 to -0.10), and global cognition (β = -0.43; 95% CI, -0.55 to -0.31) as well as a greater risk of depression (odds ratio, 1.57; 95% CI, 1.44 to 1.70) than those without hearing impairment. People who reported dual sensory impairment performed worse on all of the aforementioned outcome measures (episodic memory: β = -0.23; 95% CI, -0.31 to -0.14; mental intactness: β = -0.13; 95% CI, -0.27 to -0.0003; global cognition: β = -0.37; 95% CI, -0.55 to -0.19; depression: odds ratio, 2.19; 95% CI, 1.90 to 2.52).

CONCLUSIONS AND RELEVANCE

In this study, visual and hearing impairments were independently and together associated with poorer cognitive and depression outcomes. A more comprehensive and integrated system of care, covering vision, hearing, and cognition, is needed in China's health care system to address age-related sensory impairments.

Stress before training alters memory retrieval of a non-declarative memory in Lymnaea

Stress alters both memory formation and its retrieval. Here, we show that a combination of stressors before an associative learning event alters memory retrieval of a non-declarative memory in an invertebrate model system. Previously, two combinations of stressors were purported to prevent long-term memory (LTM) formation in 'smart' Lymnaea and this inability to form LTM was considered to be a cost of being smart. Here, we show that is not the case. The specific combinations of stressors used here cause emotional memory formation. Previously, it was shown that propranolol, a synthetic beta-blocker, altered emotional memory in Lymnaea. We show here that when propranolol but not saline is injected into smart snails before they perceive the combination of stressors, these snails form LTM. We then show that the injection of propranolol but not saline before a memory activation session allowed the memory to be recalled. That is, LTM formed but was not retrievable unless propranolol was injected pre-retrieval. Thus, the smart snails formed LTM in the face of the stressors but could not retrieve it.

Vision impairment and cognitive function among urban-dwelling malaysians aged 55 years and over from the Malaysian Elders Longitudinal Research (MELoR) study

INTRODUCTION

Published literature on vision impairment and cognitive function amongst older Malaysians remains scarce. This study investigates the association between vision impairment and cognitive function in an older Malaysian population.

METHODS

Subjects aged 55 years and above from the Malaysian Elders Longitudinal Research (MELoR) study with available information on vision and Montreal Cognitive Assessment (MoCA) scores were included. Data were obtained through a home-based interview and hospital-based health check by trained researchers. Visual acuity (VA) was assessed with logMAR score with vision impairment defined as VA 6/18 or worse in the better-seeing eye. Cognition was evaluated using the MoCA-Blind scoring procedure. Those with a MoCA-Blind score of <19/22 were considered to have cognitive impairment.

RESULTS

Data was available for 1144 participants, mean (SD) age = 68.57 (±7.23) years. Vision impairment was present in 143 (12.5 %) and 758 (66.3 %) had MoCA-Blind score of <19. Subjects with vision impairment were less likely to have a MoCA-Blind score of ≥19 (16.8 % vs 36.2 %, p < 0.001). Vision impairment was associated with poorer MoCA-Blind scores after adjustments for age, gender, and ethnicity (β = 2.064; 95 % CI, -1.282 to 3.320; P = 0.003). In those who had > 6 years of education attainment, vision impairment was associated with a significant reduction of cognitive function and remained so after adjustment for age and gender (β = 1.863; 95 % CI, 1.081-3.209; P = 0.025).

CONCLUSION

Our results suggest that vision impairment correlates with cognitive decline. Therefore, maintaining good vision is an important interventional strategy for preventing cognitive decline in older adults.

Sex Differences in Work-Stress Memory Bias and Stress Hormones

Mental health problems related to chronic stress in workers appear to be sex-specific. Psychosocial factors related to work-life balance partly explain these sex differences. In addition, physiological markers of stress can provide critical information on the mechanisms explaining how chronic stress gets "under the skull" to increase vulnerability to mental health disorders in working men and women. Stress hormones access the brain and modulate attentional and memory process in favor of threatening information. In the present study, we tested whether male and female workers present a memory bias towards work-stress related information, and whether this bias is associated with concentrations of stress hormones in reactivity to a laboratory stressor (reactive levels) and samples taken in participants' workday (diurnal levels). In total, 201 participants (144 women) aged between 18 and 72 years underwent immediate and delayed recall tasks with a 24-word list, split as a function of valence (work-stress, positive, neutral). Participants were exposed to a psychosocial stressor in between recalls. Reactivity to stress was measured with saliva samples before and after the stressor. Diurnal cortisol was also measured with five saliva samples a day, during 2 workdays. Our exploratory results showed that men presented greater cortisol reactivity to stress than women, while women recalled more positive and neutral words than men. No sex difference was detected on the recall of work-stress words, before or after exposure to stress. These results do not support the hypothesis of a sex-specific cognitive bias as an explanatory factor for sex differences in stress-related mental health disorders in healthy male and female workers. However, it is possible that such a work-stress bias is present in individuals who have developed a mental-health disorder related to workplace stress or who have had one in the recent past. Consequently, future studies could use our stress memory bias task to assess this and other hypotheses in diverse working populations.

Effect of sleep loss on executive function and plasma corticosterone levels in an arctic-breeding songbird, the Lapland longspur (Calcarius lapponicus)

Sleep is a fundamental component of vertebrate life, although its exact functions remain unclear. Animals deprived of sleep typically show reduced neurobiological performance, health, and in some cases, survival. However, a number of vertebrate taxa exhibit adaptations that permit normal activities even when sleep is reduced. Lapland longspurs (Calcarius lapponicus), arctic-breeding passerine birds, exhibit around-the-clock activity during their short breeding season, with an inactive period of ca. 4 h/day. Whether behavioral or physiological costs occur from sleep loss (SL) in this species is unknown. To assess the effects of SL, wild-caught male longspurs were placed in captivity (12L:12D) and trained for one month to successfully learn color association and spatial memory tasks. Birds were then placed in automated sleep fragmentation cages that utilize a moving wire to force movement every 1 min (60 arousals/h) during 12D (inactive period) or control conditions (during 12L; active period). After SL (or control) treatment, birds were presented with color association and spatial memory tasks a final time to assess executive function. Baseline plasma corticosterone concentration, body mass, and satiety were also measured. SL significantly elevated corticosterone levels and increased accuracy during color association recall but did not affect the overall time required to complete the task. SL had no effect upon spatial memory, body mass, or satiety. Taken together, these results suggest that Lapland longspurs exhibit a degree of behavioral, but not physiological, insensitivity to acute SL. Whether elevated plasma concentrations of corticosterone play a direct role in ameliorating cognitive deficits from SL require additional study.

Reflective and Reflexive Stress Responses of Older Adults to Three Gaming Experiences In Relation to Their Cognitive Abilities: Mixed Methods Crossover Study

BACKGROUND

The gamification of digital health provisions for older adults (eg, for rehabilitation) is a growing trend; however, many older adults are not familiar with digital games. This lack of experience could cause stress and thus impede participants' motivations to adopt these technologies.

OBJECTIVE

This crossover longitudinal multifactorial study aimed to examine the interactions between game difficulty, appraisal, cognitive ability, and physiological and cognitive responses that indicate game stress using the Affective Game Planning for Health Applications framework.

METHODS

A total of 18 volunteers (mean age 71 years, SD 4.5; 12 women) completed a three-session study to evaluate different genres of games in increasing order of difficulty (S₁-BrainGame, S₂-CarRace, and S₃-Exergame). Each session included an identical sequence of activities (t₁-Baseline, t₂-Picture encode, t₃-Play, t₄-Stroop test, t₅-Play, and t₆-Picture recall), a repeated sampling of salivary cortisol, and time-tagged ambulatory data from a wrist-worn device. Generalized estimating equations were used to investigate the effect of session×activity or session×activity×cognitive ability on physiology and cognitive performance. Scores derived from the Montreal Cognitive Assessment (MoCA) test were used to define cognitive ability (MoCA-high: MoCA>27, n=11/18). Kruskal-Wallis tests were used to test session or session×group effects on the scores of the postgame appraisal questionnaire.

RESULTS

Session×activity effects were significant on all ambulatory measures (χ²₁₀>20; P<.001) other than cortisol (P=.37). Compared with S₁ and S₂, S₃ was associated with approximately 10 bpm higher heart rate (P<.001) and approximately 5 muS higher electrodermal activity (P<.001), which were both independent of the movement caused by the exergame. Compared with S₁, we measured a moderate but statistically significant drop in the rate of hits in immediate recall and rate of delayed recall in S₃. The low-MoCA group did not differ from the high-MoCA group in general characteristics (age, general self-efficacy, and perceived stress) but was more likely to agree with statements such as digital games are too hard to learn. In addition, the low-MoCA group was more likely to dislike the gaming experience and find it useless, uninteresting, and visually more intense (χ²₁>4; P<.04). Group differences in ambulatory signals did not reach statistical significance; however, the rate of cortisol decline with respect to the baseline was significantly larger in the low-MoCA group.

CONCLUSIONS

Our results show that the experience of playing digital games was not stressful for our participants. Comparatively, the neurophysiological effects of exergame were more pronounced in the low-MoCA group, suggesting greater potential of this genre of games for cognitive and physical stimulation by gamified interventions; however, the need for enjoyment of this type of challenging game must be addressed.