Emerging Theories of Allostatic-Interoceptive Overload in Neurodegeneration

Recent integrative multilevel models offer novel insights into the etiology and course of neurodegenerative conditions. The predictive coding of allostatic-interoception theory posits that the brain adapts to environmental demands by modulating internal bodily signals through the allostatic-interoceptive system. Specifically, a domain-general allostatic-interoceptive network exerts adaptive physiological control by fine-tuning initial top-down predictions and bottom-up peripheral signaling. In this context, adequate adaptation implies the minimization of prediction errors thereby optimizing energy expenditure. Abnormalities in top-down interoceptive predictions or peripheral signaling can trigger allostatic overload states, ultimately leading to dysregulated interoceptive and bodily systems (endocrine, immunological, circulatory, etc.). In this context, environmental stress, social determinants of health, and harmful exposomes (i.e., the cumulative life-course exposition to different environmental stressors) may interact with physiological and genetic factors, dysregulating allostatic interoception and precipitating neurodegenerative processes. We review the allostatic-interoceptive overload framework across different neurodegenerative diseases, particularly in the behavioral variant frontotemporal dementia (bvFTD). We describe how concepts of allostasis and interoception could be integrated with principles of predictive coding to explain how the brain optimizes adaptive responses, while maintaining physiological stability through feedback loops with multiple organismic systems. Then, we introduce the model of allostatic-interoceptive overload of bvFTD and discuss its implications for the understanding of pathophysiological and neurocognitive abnormalities in multiple neurodegenerative conditions.

A patient with Fibromyalgia and Chronic Recurrent Multifocal Osteomyelitis: the importance of psychosomatic assessment

Background

Many patients affected by FM present different comorbidities, but to date no case of FM in patients with CRMO has been reported in literature. Several studies show the importance of psychosomatic assessment in FM, but only one reported the presence of allostatic overload.

Case presentation

In April 2022, a 21-year-old female patient, a third-year medical student, came to our clinic to be assessed and treated for FM. She presents with a diagnosis of CRMO made in 2014 and a diagnosis of FM made in 2019.

Results

At the psychiatric evaluation she presented symptoms of anxiety, depression, insomnia and reported widespread pain with the presence of almost daily headaches. From the psychosomatic point of view using DCPR-revised she presented diagnostic criteria for allostatic overload, related to study and periodic flare-ups of painful symptoms due to CRMO, persistent somatization, with musculoskeletal and gastroenterological symptoms, demoralization and type A behaviour.

Conclusion

This case shows how useful a psychosomatic assessment of the patient can be for offering insights into what stressors at the origin of allostatic overload may be present in different FM patients.

Allostatic Load in Children and Adolescents: A Systematic Review

INTRODUCTION

The concept of allostatic load encompasses the cumulative effects of both ordinary daily life events as well as major challenges, and also includes related health-damaging behavior. Allostatic overload ensues when environmental challenges exceed the individual's ability to cope. Identification of allostatic load is carried out through the use of biomarkers and clinimetric criteria. Studies are increasingly reported on allostatic load in younger populations, yet a systematic review is missing.

OBJECTIVE

The aim of the present systematic review was to summarize the current knowledge on allostatic load/overload among children and adolescents.

METHODS

PubMed, PsycINFO, Web of Science, and the Cochrane Library were searched from inception to April 2023. A manual search of the literature was also performed. We considered only studies in which allostatic load or overload were adequately described and assessed in either clinical or non-clinical populations younger than 18 years.

RESULTS

A total of 38 original investigations were included in this systematic review. Studies reported an association between allostatic load and sociodemographic characteristics (e.g., poverty, ethnicity, perceived discrimination, adverse childhood experiences) and environmental factors, as well as consequences of allostatic load on both physical and mental health among children and adolescents.

CONCLUSIONS

The findings indicate that greater allostatic load is associated with poorer health outcomes in both clinical and non-clinical pediatric populations, with possible enduring effects. The results support the clinical utility of the transdiagnostic identification of allostatic load and overload in children and adolescents across a variety of settings, with a number of potential clinical implications.

Stress and traumatic brain injury: An inherent bi-directional relationship with temporal and synergistic complexities

Traumatic brain injury (TBI) and stress are prevalent worldwide and can both result in life-altering health problems. While stress often occurs in the absence of TBI, TBI inherently involves some element of stress. Furthermore, because there is pathophysiological overlap between stress and TBI, it is likely that stress influences TBI outcomes. However, there are temporal complexities in this relationship (e.g., when the stress occurs) that have been understudied despite their potential importance. This paper begins by introducing TBI and stress and highlighting some of their possible synergistic mechanisms including inflammation, excitotoxicity, oxidative stress, hypothalamic-pituitary-adrenal axis dysregulation, and autonomic nervous system dysfunction. We next describe different temporal scenarios involving TBI and stress and review the available literature on this topic. In doing so we find initial evidence that in some contexts stress is a highly influential factor in TBI pathophysiology and recovery, and vice versa. We also identify important knowledge gaps and suggest future research avenues that will increase our understanding of this inherent bidirectional relationship and could one day result in improved patient care.

REAC Noninvasive Neurobiological Stimulation in Autism Spectrum Disorder for Alleviating Stress Impact

Objectives

Autism spectrum disorder (ASD) symptoms can become more evident because of different factors. Among these, depression, anxiety, and stress play an important role. Additionally, several studies have revealed the impact of the COVID-19 pandemic on participants with ASD. In previous studies, two noninvasive neurobiological stimulation treatments with radio electric asymmetric conveyer (REAC) technology, called neuropostural optimization (NPO) and neuropsychophysical optimization (NPPO), were shown to be effective in improving the subjective response to environmental stressors in the general population and in ASD population. Based on the proven efficacy of REAC NPO and NPPOs treatments in alleviating anxiety, stress, and depression, the purpose of this study is to verify how these treatments can reduce the severity of ASD symptoms expression, which is aggravated by depression, anxiety, and stress. The treatments' effects were perceived by caregivers and assessed by the Autism Treatment Evaluation Checklist (ATEC).

Methods

This study involved 46 children with a previous diagnosis of ASD made using the Autism Diagnostic Observation Schedule and Autism Diagnostic Interview-Revised. The participants received one session of NPO treatment and one NPPOs treatment cycle of 18 sessions, administered within approximately 3 weeks. The Autism Treatment Evaluation Checklist (ATEC) was used to evaluate the efficacy of the REAC treatments. ATEC allows to evaluate four clusters (speech or language communication; sociability; sensory or cognitive awareness; and health/physical/behavior) through a numerical scale that measures increasing levels of ASD severity.

Results

The comparison between the scores of the ATEC administered pre- and post-REAC treatments highlighted an improvement of ASD symptoms in each of the four clusters of ATEC.

Conclusions

The results confirm the usefulness of REAC treatments to optimize the individual response to environmental stressors and reduce the symptomatic expression and deficits present in ASD.

Towards an ecological definition of sepsis: a viewpoint

In critically ill patients with sepsis, there is a grave lack of effective treatment options to address the illness-defining inappropriate host response. Currently, treatment is limited to source control and supportive care, albeit with imminent approval of immune modulating drugs for COVID-19-associated lung failure the potential of host-directed strategies appears on the horizon. We suggest expanding the concept of sepsis by incorporating infectious stress within the general stress response of the cell to define sepsis as an illness state characterized by allostatic overload and failing adaptive responses along with biotic (pathogen) and abiotic (e.g., malnutrition) environmental stress factors. This would allow conceptualizing the failing organismic responses to pathogens in sepsis with an ancient response pattern depending on the energy state of cells and organs towards other environmental stressors in general. Hence, the present review aims to decipher the heuristic value of a biological definition of sepsis as a failing stress response. These considerations may motivate a better understanding of the processes underlying "host defense failure" on the organismic, organ, cell and molecular levels.

Mathematical modeling reveals how the speed of endocrine regulation should affect baseline and stress-induced glucocorticoid levels

Unpredictable environmental changes displace individuals from homeostasis and elicit a stress response. In vertebrates, the stress response is mediated mainly by glucocorticoids (GCs) which initiate physiological changes while minimizing allostatic overload. Individuals and species vary consistently in baseline and stress-induced GC levels and the speed with which GC levels can be upregulated or downregulated, but the extent to which variation in hormone regulation influences baseline and stress-induced GC levels is unclear. Using mathematical modeling, we tested how GC regulation rate, frequencies and durations of acute stressors, fitness functions, and allostatic overload affect GC levels during control and acute stress periods. As GC regulation rate slows, baseline and acute stress-induced GC levels become more similar. When the speed of up- and downregulation decreased, hormone levels became more linked to anticipated future conditions to avoid fitness costs of mismatching a new environmental state. More frequent acute stressors caused baseline and acute stress-induced GC levels to converge. When fitness was more tightly linked to hormone levels during acute stress periods than during control states, the speed of upregulation influenced optimal hormone levels more than the downregulation rate. With allostatic overload costs included, predicted GC levels were lower and more dependent on the frequency of past acute stressors. Our results show the value of optimality modeling to study the hormonal response to stressors and suggest GC levels depend on past and anticipated future environmental states as well as individual differences in hormone regulation.

Allostatic Load and Its Impact on Health: A Systematic Review

INTRODUCTION

Allostatic load refers to the cumulative burden of chronic stress and life events. It involves the interaction of different physiological systems at varying degrees of activity. When environmental challenges exceed the individual ability to cope, then allostatic overload ensues. Allostatic load is identified by the use of biomarkers and clinical criteria.

OBJECTIVE

To summarize the current knowledge on allostatic load and overload and its clinical implications based on a systematic review of the literature.

METHODS

PubMed, PsycINFO, Web of Science, and the Cochrane Library were searched from inception to December 2019. A manual search of the literature was also performed, and reference lists of the retrieved articles were examined.We considered only studies in which allostatic load or overload were adequately described and assessed in either clinical or non-clinical adult populations.

RESULTS

A total of 267 original investigations were included. They encompassed general population studies, as well as clinical studies on consequences of allostatic load/overload on both physical and mental health across a variety of settings.

CONCLUSIONS

The findings indicate that allostatic load and overload are associated with poorer health outcomes. Assessment of allostatic load provides support to the understanding of psychosocial determinants of health and lifestyle medicine. An integrated approach that includes both biological markers and clinimetric criteria is recommended.

A cross-sectional observational study

Background

Responsibility of general practitioners (GPs) in delivering safe and effective care is always high but during the COVID-19 pandemic they face even growing pressure that might result in unbearable stress load (allostatic overload, AO) leading to disease.

Objectives

We aimed to measure AO of Hungarian GPs during the COVID-19 pandemic and explore their recreational resources to identify potential protective factors against stress load.

Methods

In a mixed-method design, Fava’s clinimetric approach to AO was applied alongside the Psychosocial Index (PSI); Kellner’s symptom questionnaire (SQ) to measure depression, anxiety, hostility and somatisation and the Public Health Surveillance Well-being Scale (PHS-WB) to determine mental, social, and physical well-being. Recreational resources were mapped. Besides Chi-square and Kruskal-Wallis tests, regression analysis was applied to identify explanatory variables of AO.

Results

Data of 228 GPs (68% females) were analysed. Work-related changes caused the biggest challenges leading to AO in 60% of the sample. While female sex (OR: 1.99; CI: 1.06; 3.74, p = 0.032) and other life stresses (OR: 1.4; CI: 1.2; 1.6, p < 0.001) associated with increased odds of AO, each additional day with 30 min for recreation purposes associated with 20% decreased odds (OR: 0.838; CI: 0.72; 0.97, p = 0.020). 3–4 days a week when time was ensured for recreation associated with elevated mental and physical well-being, while 5–7 days associated with lower depressive and anxiety symptoms, somatisation, and hostility.

Conclusion

Under changing circumstances, resilience improvement through increasing time spent on recreation should be emphasised to prevent GPs from the adverse health consequences of stress load.

Physical Exercise as a Resilience Factor to Mitigate COVID-Related Allostatic Overload

INTRODUCTION

The long-lasting threat of COVID-19 makes it necessary to explore strategies to improve coping skills which enable us to master a balanced life in the face of adversity.

OBJECTIVE

To unravel the most challenging aspects of COVID-19 in a nonclinical adult population and identify predictors of lost balance and consequent allostatic overload (AO). We examined the role of regular, moderate-intensity formula aerobic exercise (312 meridian exercise) in preventing allostatic overload through increasing well-being.

METHODS

An online survey was conducted to measure CO-VID-related allostatic overload according to clinimetric criteria. The Psychosocial Index (PSI), Kellner's Symptom Questionnaire (KSQ), short Depression Anxiety Stress Scales (DASS-21), Public Health Surveillance Well-Being Scale -(PHS-WB), and Whiteley-7 were used to explore mental health characteristics. Univariate statistics logistic regression analysis and a general linear model were used.

RESULTS

According to 442 valid answers, 217 adults practiced physical exercise (PE) frequently (fPE, 3-5 times/every day) while 120 did it less regularly (1-2 times/week), and 105 did not exercise/practiced irregularly (controls). Restriction-related stressors were most challenging, resulting in AO in 29% (n = 128) of the sample. The main predictors were additional stressors (p = 0.005) and anxiety symptoms (p < 0.001). The prevalence of AO was lower (p = 0.018) in the fPE group when compared to controls. KSQ distress symptoms were also lower in fPE (p < 0.0001), while total well-being was increased (p < 0.001) after adjusting for sex, age, and number of chronic diseases. According to the PHS-WB, both physical and mental well-being were higher (p = 0.003 and p = 0.004, respectively) in fPE.

CONCLUSIONS

Frequent moderate exercise is associated with better mental and physical well-being and a lower prevalence of AO.

Takotsubo syndrome in COVID-19 era: Is psychological distress the key?

Covid-19 pandemic, starting from Wuhan, China spread all over the world and Italy was one of the most affected countries, especially in Lombardy, where, on February 20, the first confirmed case was detected. Italian Government ordered a national lockdown on the 9 th March 2020, forcing the population to severe restrictive isolation measures. The burden on mental health of the medical emergency related to COVID19 is progressively been revealed. Takotsubo syndrome (TTS), is estimated to represent 1-3% of patients admitted with suspected STEMI, mostly affecting elderly women with emotional stress and/or acute illness preceding the presentation. Comparing patients hospitalised from February to May 2020 with those of the corresponding period in 2019 we observed a significantly increased number of TTS diagnosis in 2020 (11 patients vs 3 in 2019), especially during the first period of lockdown. The only two males were patients with COVID-19 and were the only two who died in hospital. At psychological examination all patients enrolled report to have lived a particularly stressful experience at IES-R in the last year, without presenting the symptoms of a post-traumatic stress disorder. Most patients were positive to the allostatic overload. Only one patient showed a clinical cut-off for HADS and no one for the Fear COVID-19 scale. We finally concluded that subjects with pre-pandemic psychological distress may have experienced additional psychological overload, opening the door to TTS by a series of physiological alterations as the secretion of cortisol and catecholamines, making the subject more vulnerable to the onset of TTS.

Allostatic overload in patients with essential hypertension

The role of psychosocial stress in the development of essential hypertension has attracted increasing attention in the last decades, even though research findings have been often inconclusive. We specifically investigated allostatic overload (AO) in hypertensive patients using a clinimetric approach. Allostatic overload was assessed by a semi-structured research interview based on clinimetric criteria in 80 consecutive outpatients with essential hypertension (46.3 % females; mean age 62.18 ± 8.59 years; age range 47-74 years) and 80 normotensive matched controls. Three clinical interviews and two self-rating questionnaires for assessing psychological distress and well-being were also administered. Cardiac variables were collected. AO was present in 26 (32.5 %) of the hypertensive patients based on clinical interviewing, and in only 6 normotensive controls (p < .001). Hypertensive patients with AO had significantly higher levels of psychological distress than those without. Further, patients with AO displayed significantly lower levels of well-being and quality of life (p < .001). A significantly greater prevalence of psychosomatic syndromes was found to be associated with the presence of AO (p < .05), whereas no significant association was detected as to psychiatric diagnoses. Significantly greater cardiovascular risk was found among hypertensive patients reporting AO compared to those without (p < .05). The results of this study support the clinical relevance of a psychological assessment of hypertensive patients, with important implications for the non-pharmacological management of hypertension.

Clinical characterization of allostatic overload

Allostatic load reflects the cumulative effects of stressful experiences in daily life and may lead to disease over time. When the cost of chronic exposure to fluctuating or heightened neural and systemic physiologic responses exceeds the coping resources of an individual, this is referred to as "toxic stress" and allostatic overload ensues. Its determination has initially relied on measurements of an interacting network of biomarkers. More recently, clinical criteria for the determination of allostatic overload, that provide information on the underlying individual experiential causes, have been developed and used in a number of investigations. These clinimetric tools can increase the number of people screened, while putting the use of biomarkers in a psychosocial context. The criteria allow the personalization of interventions to prevent or decrease the negative impact of toxic stress on health, with particular reference to lifestyle modifications and cognitive behavioral therapy.

A Trial Integrating Different Methods to Assess Psychosocial Problems in Primary Care

BACKGROUND

A number of studies have documented psychosocial problems, psychiatric morbidity and impaired quality of life in primary care patients.

OBJECTIVE

The aim of this trial was to test the usefulness of the joint use of different diagnostic interviews and self-rated questionnaires.

METHODS

Two hundred consecutive patients in a primary care practice in Italy underwent the Structured Clinical Interview for DSM-5 and the Semi-Structured Interview for the Diagnostic Criteria for Psychosomatic Research (DCPR) in its recently revised form. As self-rated evaluations, the PsychoSocial Index, the Short-Form Health Survey and the Illness Attitude Scales were administered.

RESULTS

There were 46 patients (23%) with at least 1 DSM-5 diagnosis. Eighty-eight patients (44%) had at least 1 DCPR diagnosis, mainly maladaptive illness behavior (26.5%), allostatic overload (15.5%) and demoralization (15%). There were 47 (23.5%) patients who had a DCPR diagnosis only; 5 subjects (2.5%) had a DSM diagnosis only. Patients with DCPR syndromes displayed significantly higher self-rated levels of stress, psychological distress and maladaptive illness behavior and significantly lower levels of quality of life and well-being than patients with no diagnoses.

CONCLUSIONS

In a busy clinical setting, a simple self-rated questionnaire such as the PsychoSocial Index may afford a useful tool to unveil patient current distress. The DCPR can provide clinical information for a substantial number of patients who do not satisfy DSM-5 classification criteria and yet present with psychosocial problems, as measured by self-rated scales. The DCPR may improve the assessment and treatment plan of primary care psychologists or consulting psychiatrists.

A general neurologist's perspective on the urgent need to apply resilience thinking to the prevention and treatment of Alzheimer's disease

The goal of this article was to look at the problem of Alzheimer's disease (AD) through the lens of a socioecological resilience-thinking framework to help expand our view of the prevention and treatment of AD. This serious and complex public health problem requires a holistic systems approach. We present the view that resilience thinking, a theoretical framework that offers multidisciplinary approaches in ecology and natural resource management to solve environmental problems, can be applied to the prevention and treatment of AD. Resilience thinking explains a natural process that occurs in all complex systems in response to stressful challenges. The brain is a complex system, much like an ecosystem, and AD is a disturbance (allostatic overload) within the ecosystem of the brain. Resilience thinking gives us guidance, direction, and ideas about how to comprehensively prevent and treat AD and tackle the AD epidemic.

Chronic stress, energy transduction, and free-radical production in a reptile

Stress hormones, such as corticosterone, play a crucial role in orchestrating physiological reaction patterns shaping adapted responses to stressful environments. Concepts aiming at predicting individual and population responses to environmental stress typically consider that stress hormones and their effects on metabolic rate provide appropriate proxies for the energy budget. However, uncoupling between the biochemical processes of respiration, ATP production, and free-radical production in mitochondria may play a fundamental role in the stress response and associated life histories. In this study, we aim at dissecting sub-cellular mechanisms that link these three processes by investigating both whole-organism metabolism, liver mitochondrial oxidative phosphorylation processes (O₂ consumption and ATP production) and ROS emission in Zootoca vivipara individuals exposed 21 days to corticosterone relative to a placebo. Corticosterone enhancement had no effect on mitochondrial activity and efficiency. In parallel, the corticosterone treatment increased liver mass and mitochondrial protein content suggesting a higher liver ATP production. We also found a negative correlation between mitochondrial ROS emission and plasma corticosterone level. These results provide a proximal explanation for enhanced survival after chronic exposure to corticosterone in this species. Importantly, none of these modifications affected resting whole-body metabolic rate. Oxygen consumption, ATP, and ROS emission were thus independently affected in responses to corticosterone increase suggesting that concepts and models aiming at linking environmental stress and individual responses may misestimate energy allocation possibilities.

Does 'existential unease' predict adult multimorbidity? Analytical cohort study on embodiment based on the Norwegian HUNT population

OBJECTIVES

Multimorbidity is prevalent, and knowledge regarding its aetiology is limited. The general pathogenic impact of adverse life experiences, comprising a wide-ranging typology, is well documented and coherent with the concept allostatic overload (the long-term impact of stress on human physiology) and the notion embodiment (the conversion of sociocultural and environmental influences into physiological characteristics). Less is known about the medical relevance of subtle distress or unease. The study aim was to prospectively explore the associations between existential unease (coined as a meta-term for the included items) and multimorbidity.

SETTING

Our data are derived from an unselected Norwegian population, the Nord-Trøndelag Health Study, phases 2 (1995-1997) and 3 (2006-2008), with a mean of 11 years follow-up.

PARTICIPANTS

The analysis includes 20 365 individuals aged 20-59 years who participated in both phases and was classified without multimorbidity (with 0-1 disease) at baseline.

METHODS

From HUNT2, we selected 11 items indicating 'unease' in the realms of self-esteem, well-being, sense of coherence and social relationships. Poisson regressions were used to generate relative risk (RR) of developing multimorbidity, according to the respondents' ease/unease profile.

RESULTS

A total of 6277 (30.8%) participants developed multimorbidity. They were older, more likely to be women, smokers and with lower education. 10 of the 11 'unease' items were significantly related to the development of multimorbidity. The items 'poor self-rated health' and 'feeling dissatisfied with life' exhibited the highest RR, 1.55 and 1.44, respectively (95% CI 1.44 to 1.66 and 1.21 to 1.71). The prevalence of multimorbidity increased with the number of 'unease' factors, from 26.7% for no factor to 49.2% for 6 or more.

CONCLUSIONS

In this prospective study, 'existential unease' was associated with the development of multimorbidity in a dose-response manner. The finding indicates that existential unease increases people's vulnerability to disease, concordant with current literature regarding increased allostatic load.