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•Aging and degeneration cause changes to the brain's mechanical properties.•Mechanical properties relate to tissue health and microstructure.•Measured non-invasively with magnetic resonance elastography.•Emergence of viscoelastic structure-function relationships.•Promising imaging biomarker for neurodegenerative diseases. Neuroimaging techniques that can sensitivity characterize healthy brain aging and detect subtle neuropathologies have enormous potential to assist in the early detection of neurodegenerative conditions such as Alzheimer's disease. Magnetic resonance elastography (MRE) has recently emerged as a reliable, high-resolution, and especially sensitive technique that can noninvasively characterize tissue biomechanical properties (i.e., viscoelasticity) in vivo in the living human brain. Brain tissue viscoelasticity provides a unique biophysical signature of neuroanatomy that are representative of the composition and organization of the complex tissue microstructure. In this article, we detail how progress in brain MRE technology has provided unique insights into healthy brain aging, neurodegeneration, and structure-function relationships. We further discuss additional promising technical innovations that will enhance the specificity and sensitivity for brain MRE to reveal considerably more about brain aging as well as its potentially valuable role as an imaging biomarker of neurodegeneration. MRE sensitivity may be particularly useful for assessing the efficacy of rehabilitation strategies, assisting in differentiating between dementia subtypes, and in understanding the causal mechanisms of disease which may lead to eventual pharmacotherapeutic development.

Purpose of Review Women are twice as likely to develop post-traumatic stress disorder (PTSD) compared to men after a traumatic experience. The purpose of this mini review was to explore recent research on biological contributors to this sex difference. Recent Findings We identified 51 studies published since 2019. Studies found that beyond the influence of sex on the prevalence and symptoms of PTSD, there is evidence for and against sex-based differences in genetic and epigenetic factors ( n  = 8), brain structure and function ( n  = 11), neuroendocrine and inflammatory responses ( n  = 5), and in the role of sleep on emotional memory processing ( n  = 1). Sex differences were also observed in recovery and during PTSD treatment ( n  = 16). Finally, there is emerging evidence of sex-differentiated risk for medical and psychiatric comorbidities in PTSD ( n  = 10). Summary Rapid advances are being made using integrated multidisciplinary approaches to understand why females are at a heightened risk for developing PTSD.

Higher levels of PTSD symptoms are present among trauma-exposed females males in adulthood; however, much less is known about the emergence of this sex difference during development. In a multi-study sample of 7-18-year-olds ( = 3397), we examined the effect of sex and age on the severity of PTSD symptoms after a single incident trauma at 1 month (T1), and on symptom change after a natural recovery period of 3 (T2) and 6 months (T3). PTSD scores were harmonised across measurement types, and linear regressions were used to determine sex and age effects, adjusting for study level variance and trauma type. A sex × age interaction was observed at T1 ( < 0.001) demonstrating that older age was associated with greater PTSD symptom severity in females ( = 0.008, = 0.047), but less severe symptoms in males ( = -0.011, = 0.014). The same pattern was observed at T2 and T3, with sex differences beginning to emerge by age 12 years. PTSD symptoms decreased naturally by ~25% at T2 with little further improvement by T3. Further, females showed a greater reduction in symptoms at T3 than males, although the same effect was not observed at T2. Sex differences in PTSD symptoms become apparent during adolescence, due to opposing changes in susceptibility occurring in females and males with age. Understanding the factors contributing to these findings is likely to provide wider insight into sex-specific psychological vulnerability to trauma-related psychopathology.

Central to the investigation of the biomechanics of traumatic brain injury (TBI) and the assessment of injury risk from head impact are finite element (FE) models of the human brain. However, many existing FE human brain models have been developed with simplified representations of the parenchyma, which may limit their applicability as an injury prediction tool. Recent advances in neuroimaging techniques and brain biomechanics provide new and necessary experimental data that can improve the biofidelity of FE brain models. In this study, the CAB-20MSym template model was developed, calibrated, and extensively verified. To implement material heterogeneity, a magnetic resonance elastography (MRE) template image was leveraged to define the relative stiffness gradient of the brain model. A multi-stage inverse FE (iFE) approach was used to calibrate the material parameters that defined the underlying non-linear deviatoric response by minimizing the error between model-predicted brain displacements and experimental displacement data. This process involved calibrating the infinitesimal shear modulus of the material using low-severity, low-deformation impact cases and the material non-linearity using high-severity, high-deformation cases from a dataset of in situ brain displacements obtained from cadaveric specimens. To minimize the geometric discrepancy between the FE models used in the iFE calibration and the cadaveric specimens from which the experimental data were obtained, subject-specific models of these cadaveric brain specimens were developed and used in the calibration process. Finally, the calibrated material parameters were extensively verified using independent brain displacement data from 33 rotational head impacts, spanning multiple loading directions (sagittal, coronal, axial), magnitudes (20–40 rad/s), durations (30–60 ms), and severity. Overall, the heterogeneous CAB-20MSym template model demonstrated good biofidelity with a mean overall CORA score of 0.63 ± 0.06 when compared to in situ brain displacement data. Strains predicted by the calibrated model under non-injurious rotational impacts in human volunteers ( N = 6 ) also demonstrated similar biofidelity compared to in vivo measurements obtained from tagged magnetic resonance imaging studies. In addition to serving as an anatomically accurate model for further investigations of TBI biomechanics, the MRE-based framework for implementing material heterogeneity could serve as a foundation for incorporating subject-specific material properties in future models.

Background As a result of the COVID‐19 pandemic, school closures meant that for many households, home and school environments became intertwined. Parents and carers found themselves taking on the role as de‐facto educators, as well as balancing working from home and caring for additional members of the household. Understanding the full extent of the effects incurred by parents and carers during school closures is vital to identifying and supporting vulnerable families. This rapid review aimed to appraise the available evidence on the potential effects of the COVID‐19 pandemic on UK parents and carers. Methods Searches for academic literature were conducted using Proquest Central, Scopus, and Google Scholar between 21st and 28th April 2021 using search terms describing “parents and carers”, “COVID‐19” and the “UK”. Additional literature was identified on relevant parents and carers' organisations websites including charity reports. Results Thirty‐two articles were found relating to harms affecting parents and carers in the UK High levels of psychological distress, including anxiety and depression, were consistently identified in the general parent population, and especially in parents caring for a child with special educational needs and/or neurodevelopmental disorders (SEN/ND). Charity reports indicated that many parents, especially those from an ethnic minority background and kinship carers, were worse off financially and with food insecurities, whereas empirical evidence showed that mothers were more likely to initiate furlough for themselves compared with fathers or childless women. Domestic abuse support services also reported a sharp rise in demand during lockdown restrictions, and practitioners reported an increase in child and adolescent violence towards parents. Conclusions Given the known impacts of parental stress, mental health problems, domestic violence and financial hardship on children's development, it is critical that these findings are taken into account in case of future pandemics to minimise harms both to parents and their families. As a result of the COVID‐19 Pandemic families were encouraged to stay at home as the result of school closures and disruption to daily routine. The current rapid review investigates the impact of these disruptions on parents and caregivers across the United Kingdom. Results found a number of impacts including parent mental health, domestic violence and financial hardship, all of which can have substantial effects on children's development.

Aging and neurodegeneration impact structural brain integrity and can result in changes to behavior and cognition. Personality, a relatively stable trait in adults as compared to behavior, in part relies on normative individual differences in cellular organization of the cerebral cortex, but links between brain structure and personality expression have been mixed. One key finding is that personality has been shown to be a risk factor in the development of Alzheimer's disease, highlighting a structure–trait relationship. Magnetic resonance elastography (MRE) has been used to noninvasively study age‐related changes in tissue mechanical properties because of its high sensitivity to both the microstructural health and the structure–function relationship of the tissue. Recent advancements in MRE methodology have allowed for reliable property recovery of cortical subregions, which had previously presented challenges due to the complex geometry and overall thin structure. This study aimed to quantify age‐related changes in cortical mechanical properties and the relationship of these properties to measures of personality in an older adult population (N = 57; age 60–85 years) for the first time. Mechanical properties including shear stiffness and damping ratio were calculated for 30 bilateral regions of the cortex across all four lobes, and the NEO Personality Inventory (NEO‐PI) was used to measure neuroticism and conscientiousness in all participants. Shear stiffness and damping ratio were found to vary widely across regions of the cortex, upward of 1 kPa in stiffness and by 0.3 in damping ratio. Shear stiffness changed regionally with age, with some regions experiencing accelerated degradation compared to neighboring regions. Greater neuroticism (i.e., the tendency to experience negative emotions and vulnerability to stress) was associated with high damping ratio, indicative of poorer tissue integrity, in the rostral middle frontal cortex and the precentral gyrus. This study provides evidence of structure–trait correlates between physical mechanical properties and measures of personality in older adults and adds to the supporting literature that neurotic traits may impact brain health in cognitively normal aging. Shear stiffness and damping ratio were found to vary widely across the cortex. Shear stiffness changed regionally with age, with some regions experiencing accelerated degradation compared to neighboring regions. Greater neuroticism was associated with high damping ratio in the regions of the frontal lobe.

Background: Evidence from high-income countries (HICs) has documented a higher rate of post-traumatic stress disorder (PTSD) in females than males. However, data are limited on sex differences in PTSD from low- and middle-income countries (LMICs), despite particularly high levels of trauma experienced by LMIC youth. Objectives: In a sample of adolescents from an impoverished South African community, we examined sex differences in PTSD, as well as co-occurring depression, adolescent age, and the type and extent of trauma exposure as potential contributors to female vulnerability. Methods: Participants were recruited from high schools in the Khayelitsha area of Cape Town. Self-reported trauma exposure, PTSD and depressive symptoms were measured in 797 adolescents (62% female) aged 13-17 years. Poisson regressions were used to examine Risk Ratios (RR) based on probable PTSD diagnoses, and linear regressions were applied to assess posttraumatic stress symptom (PTSS) severity. Results: 92% of adolescents reported trauma exposure, of whom 28% had probable PTSD. Prevalence of PTSD was higher for females than for males, even when controlling for total trauma exposure (RR = 1.71, p < .001) and co-occurring depressive symptoms (RR = 1.45, p = .005). By contrast, sex differences in depression were eliminated after controlling for co-occurring PTSS. There was little evidence of age effects on the emergence of sex differences. At lower thresholds of interpersonal trauma, females showed higher levels of PTSS compared to males, but no sex differences were found at high levels of exposure. Conclusion: Higher PTSD rates are observed in adolescent females in a high adversity-LMIC sample suggesting sex differences are robust across international contexts. Sex differences in PTSD are unlikely to be explained by co-occurring depression and in this context sex differences in depression may be secondary to trauma and PTSD. However, exposure to significant interpersonal trauma appears to overrule any specific female vulnerability. Sex differences in post-traumatic stress disorder are observed in adolescence from a high-adversity LMIC. Greater female risk occurs even when adjusting for trauma exposure and depressive symptoms. Females also show greater vulnerability to lower thresholds of interpersonal trauma.

Previous studies have shown that engagement in even a single session of exercise can improve cognitive performance in the short term. However, the underlying physiological mechanisms contributing to this effect are still being studied. Recently, with improvements to advanced quantitative neuroimaging techniques, brain tissue mechanical properties can be sensitively and noninvasively measured with magnetic resonance elastography (MRE) and regional brain mechanical properties have been shown to reflect individual cognitive performance. Here we assess brain mechanical properties before and immediately after engagement in a high-intensity interval training (HIIT) regimen, as well as one-hour post-exercise. We find that immediately after exercise, subjects in the HIIT group had an average global brain stiffness decrease of 4.2% (p < 0.001), and an average brain damping ratio increase of 3.1% (p = 0.002). In contrast, control participants who did not engage in exercise showed no significant change over time in either stiffness or damping ratio. Changes in brain mechanical properties with exercise appeared to be regionally dependent, with the hippocampus decreasing in stiffness by 10.4%. We also found that one-hour after exercise, brain mechanical properties returned to initial baseline values. The magnitude of changes to brain mechanical properties also correlated with improvements in reaction time on executive control tasks (Eriksen Flanker and Stroop) with exercise. Understanding the neural changes that arise in response to exercise may inform potential mechanisms behind improvements to cognitive performance with acute exercise.

Structural ‘brain age’ is a valuable but complex biomarker for several brain disorders. The dog is an unrivalled comparator for neurological disease modeling, however canine brain morphometric diversity creates computational and statistical challenges. Using a data-driven approach, we explored complex interactions between patient metadata, brain morphometry, and neurological disease. Twenty-four morphometric parameters measured from 286 canine brain magnetic resonance imaging scans were combined with clinical parameters to generate 9,438 data points. Network analysis was used to cluster patients according to their brain morphometry profiles. An ‘aged-brain’ profile, defined by a small brain width and volume combined with ventriculomegaly, was revealed in the Boxer breed. Key features of this profile were paralleled in neutered female dogs which, relative to un-neutered females, had an 11-fold greater risk of developing brain tumours. Boxer dog and geriatric dog groups were both enriched for brain tumour diagnoses, despite a lack of geriatric Boxers within the cohort. Our findings suggest that advanced brain ageing enhances brain tumour risk in dogs and may be influenced by oestrogen deficiency—a risk factor for dementia and brain tumours in humans. Morphometric features of brain ageing in dogs, like humans, might better predict neurological disease risk than patient chronological age.

Episodic memory is particularly sensitive to normative aging; however, studies investigating the structure-function relationships that support episodic memory have primarily been limited to gross volumetric measures of brain tissue health. Magnetic resonance elastography (MRE) is an emerging non-invasive, high-resolution imaging technique that uniquely quantifies brain viscoelasticity, and as such, provides a more specific measure of neural microstructural integrity. Recently, a significant double dissociation between orbitofrontal cortex-fluid intelligence and hippocampal-relational memory structure-function relationships was observed in young adults, highlighting the potential of sensitive MRE measures for studying brain health and its relation to cognitive function. However, the structure-function relationship observed by MRE has not yet been explored in healthy older adults. In this study, we examined the relationship between hippocampal (HC) viscoelasticity and episodic memory in cognitively healthy adults aged 66–73 years (N = 11), as measured with the verbal-paired associates (VPA) subtest from the Wechsler Memory Scale (WMS-R). Given the particular dependence of verbal memory tasks on the left HC, unilateral HC MRE measurements were considered for the first time. A significant negative correlation was found between left HC damping ratio, ξ and VPA recall score (rs = −0.77, p = 0.009), which is consistent with previous findings of a relationship between HC ξ and memory performance in young adults. Conversely, correlations between right HC ξ with VPA recall score were not significant. These results highlight the utility of MRE to study cognitive decline and brain aging and suggest its possible use as a sensitive imaging biomarker for memory-related impairments.