Allostatic load and reduced cortical thickness in schizophrenia

Association of allostatic load with depression, anxiety, and suicide: a prospective cohort study

BACKGROUND

Allostatic load (AL) is an objective measure of the biological components of chronic stress within clinical practice, potentially influencing depression, anxiety, and suicide. This study investigates the association between AL and these mental disorders.

METHODS

In this cohort study of 333,017 adults, participants without prior diagnoses of depression, anxiety, or suicide were observed from March 13, 2006, to October 31, 2022. AL was estimated using 10 biomarkers reflecting metabolic, cardiovascular, and inflammatory dysregulation. Diagnoses were based on the International Classification of Diseases 10th Revision (ICD-10). We performed Cox proportional hazards models to assess the relationship between AL and these mental disorders. Additionally, we conducted subgroup analyses for sex, age, and Townsend Deprivation Index (TDI), along with sensitivity analyses.

RESULTS

The median follow-up period was 12.99 years. Over the follow-up period, 13,441 (4.04%) participants developed depression, 13,903 (4.17%) developed anxiety and 796 (0.24%) committed suicide. In fully adjusted model, individuals with high AL had an increased risk of depression (HR = 1.389, P = 8.38 ×10-27), anxiety (HR = 1.304, P = 5.82 ×10-19) and suicide (HR = 1.433, P = 4.46 ×10-3). Women and younger individuals with high AL were vulnerable to depression and anxiety, while moderate AL levels were significantly associated with suicide in men and younger participants. Moreover, individuals with middle and high AL had an elevated risk of comorbid depression and anxiety.

CONCLUSIONS

High AL is positively associated with increased risks of depression, anxiety, and suicide, highlighting its potential as a predictive tool in mental health.

Influenza A virus during pregnancy disrupts maternal intestinal immunity and fetal cortical development in a dose- and time-dependent manner

Epidemiological studies link exposure to viral infection during pregnancy, including influenza A virus (IAV) infection, with increased incidence of neurodevelopmental disorders (NDDs) in offspring. Models of maternal immune activation (MIA) using viral mimetics demonstrate that activation of maternal intestinal T helper 17 (TH17) cells, which produce effector cytokine interleukin (IL)-17, leads to aberrant fetal brain development, such as neocortical malformations. Fetal microglia and border-associated macrophages (BAMs) also serve as potential cellular mediators of MIA-induced cortical abnormalities. However, neither the inflammation-induced TH17 cell pathway nor fetal brain-resident macrophages have been thoroughly examined in models of live viral infection during pregnancy. Here, we inoculated pregnant mice with two infectious doses of IAV and evaluated peak innate and adaptive immune responses in the dam and fetus. While respiratory IAV infection led to dose-dependent maternal colonic shortening and microbial dysregulation, there was no elevation in intestinal TH17 cells nor IL-17. Systemically, IAV resulted in consistent dose- and time-dependent increases in IL-6 and IFN-γ. Fetal cortical abnormalities and global changes in fetal brain transcripts were observable in the high-but not the moderate-dose IAV group. Profiling of fetal microglia and BAMs revealed dose- and time-dependent differences in the numbers of meningeal but not choroid plexus BAMs, while microglial numbers and proliferative capacity of Iba1+ cells remained constant. Fetal brain-resident macrophages increased phagocytic CD68 expression, also in a dose- and time-dependent fashion. Taken together, our findings indicate that certain features of MIA are conserved between mimetic and live virus models, while others are not. Overall, we provide consistent evidence of an infection severity threshold for downstream maternal inflammation and fetal cortical abnormalities, which recapitulates a key feature of the epidemiological data and further underscores the importance of using live pathogens in NDD modeling to better evaluate the complete immune response and to improve translation to the clinic.

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.

Elucidating individual differences in chronic pain and whole person health with allostatic load biomarkers

Chronic pain is a stressor that affects whole person functioning. Persistent and prolonged activation of the body's stress systems without adequate recovery can result in measurable physiological and neurobiological dysregulation recognized as allostatic load. We and others have shown chronic pain is associated with measures of allostatic load including clinical biomarker composites, telomere length, and brain structures. Less is known regarding how different measures of allostatic load align. The purpose of the study was to evaluate relationships among two measures of allostatic load: a clinical composite and pain-related brain structures, pain, function, and socioenvironmental measures. Participants were non-Hispanic black and non-Hispanic white community-dwelling adults between 45 and 85 years old with knee pain. Data were from a brain MRI, questionnaires specific to pain, physical and psychosocial function, and a blood draw. Individuals with all measures for the clinical composite were included in the analysis (n = 175). Indicating higher allostatic load, higher levels of the clinical composite were associated with thinner insula cortices with trends for thinner inferior temporal lobes and dorsolateral prefrontal cortices (DLPFC). Higher allostatic load as measured by the clinical composite was associated with greater knee osteoarthritis pathology, pain disability, and lower physical function. Lower allostatic load as indicated by thicker insula cortices was associated with higher income and education, and greater physical functioning. Thicker insula and DLPFC were associated with a lower chronic pain stage. Multiple linear regression models with pain and socioenvironmental measures as the predictors were significant for the clinical composite, insular, and inferior temporal lobes. We replicate our previously reported bilateral temporal lobe group difference pattern and show that individuals with high chronic pain stage and greater socioenvironmental risk have a higher allostatic load as measured by the clinical composite compared to those individuals with high chronic pain stage and greater socioenvironmental buffers. Although brain structure differences are shown in individuals with chronic pain, brain MRIs are not yet clinically applicable. Our findings suggest that a clinical composite measure of allostatic load may help identify individuals with chronic pain who have biological vulnerabilities which increase the risk for poor health outcomes.

Hippocampal Connectivity with the Default Mode Network is Linked to Hippocampal Volume in the Clinical High Risk for Psychosis Syndrome and Healthy Individuals

Reduced hippocampal volume (HV) is an established brain morphological feature of psychiatric conditions. HV is associated with brain connectivity in humans and non-human animals and altered connectivity is associated with risk for psychiatric illness. Associations between HV and connectivity remain poorly characterized in humans, and especially in phases of psychiatric illness that precede disease onset. This study examined associations between HV and hippocampal functional connectivity (FC) during rest in 141 healthy controls and 248 individuals at-risk for psychosis. Significant inverse associations between HV and hippocampal FC with the inferior parietal lobe (IPL) and thalamus were observed. Select associations between hippocampal FC and HV were moderated by diagnostic group. Significant moderation results shifted from implicating the IPL to the temporal pole after excluding participants on antipsychotic medication. Considered together, this work implicates hippocampal FC with the temporoparietal junction, within a specialized subsystem of the default mode network, as sensitive to HV.

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

Allostatic Load Measurement: A Systematic Review of Reviews, Database Inventory, and Considerations for Neighborhood Research

BACKGROUND

Neighborhoods are critical to understanding how environments influence health outcomes. Prolonged environmental stressors, such as a lack of green spaces and neighborhood socioeconomic disadvantage, have been associated with higher allostatic load levels. Since allostatic load levels experienced earlier in life have stronger associations with mortality risk, neighborhoods may be uniquely suited to monitor and mitigate the impacts of environmental stressors. Researchers often study allostatic load in neighborhoods by utilizing administrative boundaries within publicly accessible databases as proxies for neighborhoods.

METHODS

This systematic review of reviews aims to identify commonly used biomarkers in the measurement of allostatic load, compare measurement approaches, inventory databases to study allostatic load, and spotlight considerations referenced in the literature where allostatic load is studied in neighborhoods. The review was conducted using the search term "allostatic load" in the MEDLINE, CINAHL, and PsychINFO databases. The search results were filtered to include reviews.

RESULTS

The search returned 499 articles after deduplication. Overall, 18 synthesis reviews met the inclusion criteria and were retained for extraction. The synthesis reviews analyzed represented 238 studies published from 1995 to 2020. The original ten biomarkers were most often used to measure allostatic load. More recently, body mass index and C-reactive protein have additionally been frequently used to measure allostatic load burden.

CONCLUSIONS

The scientific contributions of this study are that we have identified a clear gap in geographic considerations when studying allostatic load. The implication of this study is that we have highlighted geographic concepts when conducting neighborhood-level research using administrative databases as a neighborhood proxy and outlined emerging future trends that can enable future study of allostatic load in the neighborhood context.

The association between allostatic load and brain: A systematic review

Allostatic load (AL) refers to prolonged dysregulation related to chronic stress that affects brain regions such as the hippocampus, amygdala, and prefrontal cortex (PFC). Higher levels of AL have been associated with poor health outcomes, including psychiatric disorders, cognitive decline, and chronic somatic conditions. However, still little is known about the relationship between AL and the brain, and the mechanisms explaining the damaging effects of stress-related biological dysregulations. Therefore, we aimed to perform a systematic review of studies investigating the association of the AL index with brain structure and functioning in adult populations. PubMed/MEDLINE, CINAHL, Academic Search Complete and Web of Science were searched from their inception until August, 9th 2021. A total of 13 studies were included in the qualitative synthesis. There was a high between-study heterogeneity with respect to the methods used to calculate the AL index and brain parameters. All studies confirmed the associations between a higher AL index and alterations in various brain areas, especially: 1) the hippocampus, white matter volume, gray matter volume, and density in the older adults; 2) the cortex, fornix, hippocampus and choroid plexus in patients with schizophrenia spectrum disorders; and 3) whole-brain white matter tracts, cortical gray matter volume, and cortical thickness in overweight subjects. Overall, the findings of this systematic review imply that an elevated AL index might be associated with various neurostructural and neurofunctional alterations. Some of these associations may appear regardless of clinical or non-clinical populations being investigated (e.g., white matter tracts), whereas others may appear in specific populations (e.g., cortical thinning in overweight/obesity and schizophrenia spectrum disorders). However, additional studies utilizing a consistent approach to calculating the AL index are needed to extend these findings and indicate populations that are most vulnerable to the damaging effects of AL.

Neurodevelopmental aspects of adverse childhood experiences in psychosis: Relevance of the allostatic load concept

Previous studies have shown that neurodevelopmental characteristics of adverse childhood experiences (ACEs), such as their accumulation and minimal age at exposure, might moderate their impact on clinical expression of psychosis. However, it remains unknown as to whether specific neurodevelopmental characteristics of ACEs are associated with biological alterations observed in psychosis. In this study, we tested the hypothesis that younger minimal age at exposure as well as greater accumulation and severity of ACEs are associated with systemic biological dysregulations captured by the allostatic load (AL) index in patients with psychosis. The present study included 65 inpatients with psychotic disorders and 56 healthy controls (HCs). A total of 15 biomarkers were used to measure the AL index. Individuals with psychosis had significantly higher AL index as well as they reported greater accumulation and severity of ACEs compared to HCs. After adjustment for age, sex, the number of education years and the dosage of antipsychotics, greater accumulation of ACEs and younger minimal age at exposure were significantly associated with higher AL index in patients with psychosis. None of neurodevelopmental characteristics of ACEs was associated with the AL index in HCs. Our findings indicate that greater accumulation of ACEs and younger minimal age at exposure are related to biological dysregulations captured by the AL index in patients with psychosis. Future studies investigating the role of ACEs in the pathophysiology of psychosis need to consider their neurodevelopmental characteristics. It is also important to further explore timing of exposure to indicate critical developmental periods related to psychosis risk and better inform potential interventions.

Peripheral inflammation levels associated with degree of advanced brain aging in schizophrenia

Brain structural abnormalities have been demonstrated in schizophrenia (SZ); these resemble those seen in typical aging, but are seen at younger ages. Furthermore, SZ is associated with accelerated global brain aging, as measured by brain structure-based brain predicted age difference (Brain-PAD). High heterogeneity exists in the degree of brain abnormalities in SZ, and individual differences may be related to levels of peripheral inflammation and may relate to cognitive deficits and negative symptoms. The goal of our study was to investigate the relationship between brain aging, peripheral inflammation, and symptoms of SZ. We hypothesized older brain-PAD in SZ vs. healthy comparison (HC) participants, as well as positive relationships of brain-PAD with peripheral inflammation markers and symptoms in SZ. We analyzed data from two cross-sectional studies in SZ (n = 26; M/F: 21/5) and HC (n = 28; 20/8) (22-64 years). Brain-PAD was calculated using a previously validated Gaussian process regression model applied to raw T1-weighted MRI data. Plasma levels of inflammatory biomarkers (CRP, Eotaxin, Fractalkine, IP10, IL6, IL10, ICAM1, IFNγ, MCP1, MIP1β, SAA, TNFα, VEGF, VCAM1) and cognitive and negative symptoms were assessed. We observed a higher brain-PAD in SZ vs. HC, and advanced brain age relative to chronological age was related to higher peripheral levels of TNFα in the overall group and in the SZ group; other inflammatory markers were not related to brain-PAD. Within the SZ group, we observed no association between cognitive or negative symptoms and brain-PAD. These results support our hypothesis of advanced brain aging in SZ. Furthermore, our findings on the relationship of the pro-inflammatory cytokine TNFα with higher brain-PAD of SZ are relevant to explain heterogeneity of brain ages in SZ, but we did not find strong evidence for cognitive or negative symptom relationships with brain-PAD.

Allostatic-Interoceptive Overload in Frontotemporal Dementia

BACKGROUND

The predictive coding theory of allostatic-interoceptive load states that brain networks mediating autonomic regulation and interoceptive-exteroceptive balance regulate the internal milieu to anticipate future needs and environmental demands. These functions seem to be distinctly compromised in behavioral variant frontotemporal dementia (bvFTD), including alterations of the allostatic-interoceptive network (AIN). Here, we hypothesize that bvFTD is typified by an allostatic-interoceptive overload.

METHODS

We assessed resting-state heartbeat evoked potential (rsHEP) modulation as well as its behavioral and multimodal neuroimaging correlates in patients with bvFTD relative to healthy control subjects and patients with Alzheimer's disease (N = 94). We measured 1) resting-state electroencephalography (to assess the rsHEP, prompted by visceral inputs and modulated by internal body sensing), 2) associations between rsHEP and its neural generators (source location), 3) cognitive disturbances (cognitive state, executive functions, facial emotion recognition), 4) brain atrophy, and 5) resting-state functional magnetic resonance imaging functional connectivity (AIN vs. control networks).

RESULTS

Relative to healthy control subjects and patients with Alzheimer's disease, patients with bvFTD presented more negative rsHEP amplitudes with sources in critical hubs of the AIN (insula, amygdala, somatosensory cortex, hippocampus, anterior cingulate cortex). This exacerbated rsHEP modulation selectively predicted the patients' cognitive profile (including cognitive decline, executive dysfunction, and emotional impairments). In addition, increased rsHEP modulation in bvFTD was associated with decreased brain volume and connectivity of the AIN. Machine learning results confirmed AIN specificity in predicting the bvFTD group.

CONCLUSIONS

Altogether, these results suggest that bvFTD may be characterized by an allostatic-interoceptive overload manifested in ongoing electrophysiological markers, brain atrophy, functional networks, and cognition.

Allostatic load and systemic comorbidities in psychiatric disorders

Psychiatric disorders are complex, disabling, and chronic conditions that are often accompanied by one or more systemic medical comorbidities. In this narrative review, we provide an overview of the allostatic load concept, which represents a multi-system dysregulation in response to chronic stress and link it to systemic comorbidities associated with psychiatric disorders. We synthesized published literature gathered using Medline (Ovid), Scopus, and PsychInfo and identified a high frequency of systemic comorbidities for both mood and psychotic disorders. The identified cardiovascular, metabolic, and immune comorbidities may represent the result of chronic wear and tear caused by a complex interaction between chronic psychosocial stress, health risk behaviors, pharmacological stressors, and the biological systems involved in the development of allostatic load. These findings support the notion that psychiatric disorders should be re-conceptualized as systemic disorders, affecting the brain and systemic biological pathways in an interconnected fashion to result in systemic comorbidities. We suggest that the multi-systemic and multi-dimensional approach that drives the allostatic load concept should be considered for understanding comorbidities in vulnerable psychiatric patients.

Life Event Stress and Reduced Cortical Thickness in Youth at Clinical High Risk for Psychosis and Healthy Control Subjects

BACKGROUND

A decline in cortical thickness during early life appears to be a normal neuromaturational process. Accelerated cortical thinning has been linked with conversion to psychosis among individuals at clinical high risk for psychosis (CHR-P). Previous research indicates that exposure to life event stress (LES) is associated with exaggerated cortical thinning in both healthy and clinical populations, and LES is also linked with conversion to psychosis in CHR-P. To date, there are no reports on the relationship of LES with cortical thickness in CHR-P. This study examines this relationship and whether LES is linked with cortical thinning to a greater degree in individuals at CHR-P who convert to psychosis compared with individuals at CHR-P who do not convert and healthy control subjects.

METHODS

Controlling for age and gender (364 male, 262 female), this study examined associations between LES and baseline cortical thickness in 436 individuals at CHR-P (375 nonconverters and 61 converters) and 190 comparison subjects in the North American Prodrome Longitudinal Study.

RESULTS

Findings indicate that prebaseline cumulative LES is associated with reduced baseline cortical thickness in several regions among the CHR-P and control groups. Evidence suggests that LES is a risk factor for thinner cortex to the same extent across diagnostic groups, while CHR-P status is linked with thinner cortex in select regions after accounting for LES.

CONCLUSIONS

This research provides additional evidence to support the role of LES in cortical thinning in both healthy youth and those at CHR-P. Potential underlying mechanisms of the findings and implications for future research are discussed.

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.

Allostatic Load Effects on Cortical and Cognitive Deficits in Essentially Normotensive, Normoweight Patients with Schizophrenia

Reduced cortical gray matter integrity and cognitive abilities are among core deficits in schizophrenia. We hypothesized that higher allostatic load (AL) that accounts for exposure to chronic stress is a contributor to structural and cognitive deficits in schizophrenia. One hundred and sixty-seven schizophrenia patients who were on average with normal weight, normal systolic, and diastolic blood pressure and 72 healthy controls were enrolled in the study. Group differences in subclinical cardiovascular, metabolic, immune, and neuroendocrine biological markers as indexed by AL and contribution of AL components to the structural and cognitive deficits in schizophrenia were explored. Compared with controls, schizophrenia patients who were normotensive, normoweight, and had low total cholesterol levels still had significantly higher AL mainly due to lower high-density lipoprotein cholesterol and higher heart rate, waist-hip ratio, hemoglobinA1c, hypersensitive C-reactive protein, and overnight-urine cortisol levels. Patients also had decreased whole-brain mean cortical thickness, and lower cognition assessed by the MATRICS consensus cognitive battery. AL was inversely correlated with mean cortical thickness and cognition in schizophrenia, while none of these relationships existed in controls. Mediation analyses showed the effect of AL on cognitive deficits in schizophrenia was significantly mediated by cortical thinning, and the most significant mediating cortical area was the left superior frontal gyrus. Cortical thickness may act as a mediator between AL and cognitive deficits in schizophrenia. Early intervention strategies to reduce cortical thinning and cognitive dysfunction in schizophrenia should target specific aspects of their high AL in addition to weight gain, hypertension and high cholesterol levels.

Association of working memory and elevated overnight urinary norepinephrine in patients with schizophrenia

INTRODUCTION

Norepinephrine has both central and peripheral origins and is known to influence cognitive processes in attention, learning, and working memory, but the research regarding the impact of norepinephrine on cognition in schizophrenia remains sparse, and mainly focuses on centrally regulated noradrenergic effects. This study examined the relationship between cumulative overnight norepinephrine levels in the urine and working memory in patients with schizophrenia and healthy controls.

METHODS

Urinary catecholamines were collected overnight in patients with schizophrenia (n = 75) and healthy controls (n = 33). Working memory was assessed using the digit sequencing task.

RESULTS

Patients showed significantly higher average levels of overnight norepinephrine (t(103.10) = -3.16, p = 0.002) and reduced working memory performance (t(90) = 3.87, p = 0.001) compared with healthy individuals. There was a significant negative correlation between norepinephrine and working memory in patients (r = -0.38, p = 0.005), but not in controls (r = 0.08, p = 0.67). After controlling for age, sex, antipsychotic medications, and serotonin-norepinephrine reuptake inhibitor-based antidepressants, the correlation remained significant (r = -0.41, p = 0.004).

CONCLUSIONS

High peripheral overnight levels of urinary norepinephrine are associated with lower working memory performance in patients with schizophrenia. These results parallel previous studies suggesting that high levels of central norepinephrine may result in working memory impairments. As norepinephrine rapidly breaks down and usually does not pass through the blood-brain barrier, the potential effect of peripheral cumulative norepinephrine on working memory is intriguing, and needs to be further investigated.

Neuroimaging Markers of Resiliency in Youth at Clinical High Risk for Psychosis: A Qualitative Review

Psychotic disorders are highly debilitating and constitute a major public health burden. Identifying markers of psychosis risk and resilience is a necessary step toward understanding etiology and informing prevention and treatment efforts in individuals at clinical high risk (CHR) for psychosis. In this context, it is important to consider that neural risk markers have been particularly useful in identifying mechanistic determinants along with predicting clinical outcomes. Notably, despite a growing body of supportive literature and the promise of recent findings identifying potential neural markers, the current work on CHR resilience markers has received little attention. The present review provides a brief overview of brain-based risk markers with a focus on predicting symptom course. Next, the review turns to protective markers, examining research from nonpsychiatric and schizophrenia fields to build an understanding of framing, priorities, and potential, applying these ideas to contextualizing a small but informative body of resiliency-relevant CHR research. Four domains (neurocognition, emotion regulation, allostatic load, and sensory and sensorimotor function) were identified and are discussed in terms of behavioral and neural markers. Taken together, the literature suggests significant predictive value for brain-based markers for individuals at CHR for psychosis, and the limited but compelling resiliency work highlights the critical importance of expanding this promising area of inquiry.

Relationship between allostatic load and clinical outcomes in youth at ultra-high risk for psychosis in the NEURAPRO study

Individuals at ultra-high risk (UHR) for psychosis have an elevated risk of developing psychosis and other psychiatric outcomes. Risk biomarkers can assist in delineating individual risk and allow better prediction of longer-term outcomes. The aim of the present study was to examine if allostatic load (AL), a multisystem index of neuroendocrine, cardiovascular, immune and metabolic dysregulation, is associated with clinical outcomes in youth at UHR for psychosis. AL was measured in 106 participants of the NEURAPRO study (n = 70 female, n = 36 male; mean age 17.21, SD 2.37), a multicentre randomized-controlled trial of long-chain omega-3 polyunsaturated fatty acids versus placebo in people at UHR for psychosis. Psychiatric symptoms and social and occupational functioning were assessed at baseline and 6 and 12 months after study intake. Multivariate linear and logistic regression models were used to test the relationship between AL and clinical outcomes. High AL at baseline was associated with poor social and occupational functioning at 6 months (β = -0.224, p = 0.025) and with more severe manic symptoms at 6 months (β = 0.207, p = 0.026), taking into account relevant covariates including age and smoking status. No significant associations were observed at the 12-month follow-up assessment or with any other clinical outcome measures. Our data provide initial evidence for a link between AL and impaired functioning in individuals at UHR for psychosis. Further studies are needed to evaluate AL as a potential predictor of early treatment response.

Assessment of brain cholesterol metabolism biomarker 24S-hydroxycholesterol in schizophrenia

Plasma 24S-hydroxycholesterol mostly originates in brain tissue and likely reflects the turnover of cholesterol in the central nervous system. As cholesterol is disproportionally enriched in many key brain structures, 24S-hydroxycholesterol is a promising biomarker for psychiatric and neurologic disorders that impact brain structure. We hypothesized that, as schizophrenia patients have widely reported gray and white matter deficits, they would have abnormal levels of plasma 24S-hydroxycholesterol, and that plasma levels of 24S-hydroxycholesterol would be associated with brain structural and functional biomarkers for schizophrenia. Plasma levels of 24S-hydroxycholesterol were measured in 226 individuals with schizophrenia and 204 healthy controls. The results showed that levels of 24S-hydroxycholesterol were not significantly different between patients and controls. Age was significantly and negatively correlated with 24S-hydroxycholesterol in both groups, and in both groups, females had significantly higher levels of 24S-hydroxycholesterol compared to males. Levels of 24S-hydroxycholesterol were not related to average fractional anisotropy of white matter or cortical thickness, or to cognitive deficits in schizophrenia. Based on these results from a large sample and using multiple brain biomarkers, we conclude there is little to no value of plasma 24S-hydroxycholesterol as a brain metabolite biomarker for schizophrenia.

A history of childhood trauma and allostatic load in patients with psychotic disorders with respect to stress coping strategies

Elevated allostatic load (AL) index, which is a cumulative measure of biological dysregulations associated with stress exposure, has been demonstrated in patients with psychosis. However, it remains unknown whether a history of childhood trauma (CT) might contribute to elevated AL index in psychosis. Therefore, we aimed to investigate the association between AL index, a history of CT and coping styles in patients with psychotic disorders. Participants were 65 patients with schizophrenia-spectrum disorders and 56 healthy controls (HCs). The AL index was computed based on percentile distributions of 15 biomarkers in HCs. The AL index was significantly higher in patients with psychosis. A history of parental antipathy was associated with elevated AL index in both groups of participants. A history of any categories of CT and sexual abuse were associated with higher AL index only in patients with psychosis. Social diversion (seeking social interactions in case of stressful experiences) mediated the association between sexual abuse and the AL index in the group of patients. There was a significant direct effect of sexual abuse on the AL index (this specific CT was associated with higher AL index). However, indirect effect of sexual trauma on AL through social diversion was opposite to direct effect. Childhood adversities, especially sexual abuse and parental antipathy, might contribute to elevated AL index in patients with psychosis. The effect of sexual abuse on the AL index might be specific to psychosis. Engagement in social interactions in case of stressful situations might alleviate biological dysregulations associated with CT.

Choroid Plexus Enlargement and Allostatic Load in Schizophrenia

Although schizophrenia is a brain disorder, increasing evidence suggests that there may be body-wide involvement in this illness. However, direct evidence of brain structures involved in the presumed peripheral-central interaction in schizophrenia is still unclear. Seventy-nine previously treatment-naïve first-episode schizophrenia patients who were within 2-week antipsychotics initial stabilization, and 41 age- and sex-matched healthy controls were enrolled in the study. Group differences in subcortical brain regional structures measured by MRI and the subclinical cardiovascular, metabolic, immune, and neuroendocrine biomarkers as indexed by allostatic load, and their associations were explored. Compared with controls, patients with schizophrenia had significantly higher allostatic load (P = .001). Lateral ventricle (P < .001), choroid plexus (P < .001), and thalamus volumes (P < .001) were significantly larger, whereas amygdala volume (P = .001) was significantly smaller in patients. The choroid plexus alone was significantly correlated with higher allostatic load after age, sex, education level, and the total intracranial volume were taken into account (t = 3.60, P < .001). Allostatic load was also significantly correlated with PANSS positive (r = 0.28, P = .016) and negative (r = -0.31, P = .008) symptoms, but in opposite directions. The peripheral multisystemic and central nervous system abnormalities in schizophrenia may interact through the choroid plexus during the early stage of the illness. The choroid plexus might provide a sensitive structural biomarker to study the treatment and prevention of brain-periphery interaction abnormalities in schizophrenia.

Stress, Allostatic Load, and Psychosis: One Step Forward in Research But Where to Go Next?

Stress exposure leads to the activation of several biological mechanisms that have been termed allostasis. These processes enable adaptation to novel situations; however; their prolonged activation exerts systemic and detrimental effects called the allostatic load (AL). The AL concept represents one of useful paradigms to describe biological consequences of chronic stress that might lead to a number of disease outcomes. The AL index, which is a collective measure of cardiovascular, metabolic, neuroendocrine, and immune dysregulations associated with stress exposure, has been found to predict morbidity and mortality in non-clinical populations. Consequently, it has been proposed that the AL concept might be a useful framework to describe biological consequences of chronic stress exposure in patients with psychotic disorders. This perspective article is an overview of studies investigating the AL index and its clinical correlates in patients with psychotic disorders. These studies have consistently reported elevated AL index in patients at the early and chronic course of psychosis. In addition, the AL index has been associated with a higher severity of positive and depressive symptoms, working memory impairments, and lower general functioning. The article provides some critical appraisal of studies in this field and indicates several future directions for investigating the AL concept in psychosis.

The Role of Hippocampal Functional Connectivity on Multisystem Subclinical Abnormalities in Schizophrenia

OBJECTIVE

Schizophrenia is associated with excess medical mortality: patients have an average life expectancy one to two decades shorter than the general population. This study investigates the relationship between aberrant hippocampal resting-state functional connectivity in schizophrenia and cumulative subclinical effects of chronic stress on metabolic, cardiovascular, and immune function using the allostatic load index.

METHODS

Cumulative stress was estimated using allostatic load total score (range, 0-13) in 46 patients with schizophrenia and 31 controls matched for age and sex (patients: age = 36.1 [13.7] years, sex = 32/14 male/female; controls: age = 35.5 [14.1], sex = 21/10 male/female). Hippocampal functional connectivity was assessed using resting-state functional magnetic resonance imaging; hippocampal structural connectivity was assessed using fornix fractional anisotropy. Linear regression analysis was used a) to test the hypothesis that aberrant hippocampal resting-state functional connectivity in schizophrenia (identified in analysis of schizophrenia - control differences) is associated with elevated allostatic load scores in patients and b) to determine the association between fornix fractional anisotropy with allostatic load.

RESULTS

In patients, higher allostatic load was significantly associated with reduced resting functional connectivity between the left hippocampus and right cingulate cortex and left precentral gyrus, but higher connectivity between the right hippocampus and left cerebellum lobe VI (corrected p values <. 05). In controls, reductions in both hippocampal structural connectivity and hippocampal-cingulate functional connectivity were associated with higher allostatic load scores.

CONCLUSIONS

These findings support basic neuroscience evidence that cumulative stress and hippocampal function are closely connected and suggest that abnormal hippocampal functional communication in schizophrenia may be related to elevated multisystem subclinical medical issues in patients as indexed by allostatic load.

Allostatic load index and its clinical correlates at various stages of psychosis

Accumulating evidence indicates systemic biological dysregulations in patients with psychosis that have been conceptualized as the "allostatic load" (AL) index. We aimed to investigate the AL index in 37 subjects at familial high risk of psychosis (FHRP), 42 first-episode psychosis (FEP) patients, 25 acutely relapsed schizophrenia (SCZ-AR) patients and 42 healthy controls (HCs), taking into account psychopathology and cognitive impairment. The AL index was calculated based on 15 biomarkers (cardiovascular markers, anthropometric measures, inflammatory markers, glucose homeostasis parameters, lipids and steroids). Cognition was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The AL index was significantly higher in patients with psychosis and FHR-P individuals compared to HCs. Patients with FEP and FHR-P individuals had similar AL index. Moreover, the AL index was significantly higher in SCZ-AR patients compared to other groups of participants. Higher AL index was associated with more severe general psychopathology and depressive symptoms, lower scores of attention (total score, digit span and digit coding tasks) and semantic fluency, as well as worse general functioning in patients with psychosis. There was a significant negative correlation between the AL index and the scores of attention (total score and digit coding task) in FHR-P individuals. No significant correlations between the AL index and cognition were found in HCs. Our results indicate that biological dysregulations, captured by the AL index, appear already in FHR-P individuals and progress with psychotic exacerbations. Elevated AL index might contribute to cognitive impairments in FHR-P individuals and patients with psychosis.

Mapping cortical surface features in treatment resistant schizophrenia with in vivo structural MRI

Decreases in cortical volume (CV), thickness (CT) and surface area (SA) have been reported in individuals with schizophrenia by in vivo MRI studies. However, there are few studies that examine these cortical measures as potential biomarkers of treatment resistance (TR) and treatment response (NTR) in schizophrenia. This study used structural MRI to examine differences in CV, CT, and SA in 42 adults with schizophrenia (TR = 21, NTR = 21) and 23 healthy controls (HC) to test the hypothesis that individuals with TR schizophrenia have significantly greater reductions in these cortical measures compared to individuals with NTR schizophrenia. We found that individuals with TR schizophrenia showed significant reductions in CV and CT compared to individuals with NTR schizophrenia in right frontal and precentral regions, right parietal and occipital cortex, left temporal cortex and bilateral cingulate cortex. In line with previous literature, the temporal lobe and cingulate gyrus in both patient groups showed significant reductions of all three measures when compared to healthy controls. Taken together these results suggest that regional changes in CV and CT may index mechanisms specific to TR schizophrenia and potentially identify patients with TR schizophrenia for earlier treatment.

Coping styles and symptomatic manifestation of first-episode psychosis: Focus on cognitive performance

Cognitive deficits are widely observed in patients with psychosis and represent one of most important determinants of functional outcomes. It has been shown that patients with psychosis prefer maladaptive coping strategies over active coping styles. However, it remains unknown whether cognitive impairments are related to coping styles in psychotic disorders. Therefore, the aim of this study was to assess whether cognitive deficits observed in patients with first-episode psychosis (FEP) might impact the use of specific coping strategies. We recruited 40 FEP patients and 35 healthy controls. In our study, FEP patients were more likely to use maladaptive coping styles after adjustment for education level and medication effects. The use of maladaptive coping strategies was associated with greater impairments of visuospatial/constructional abilities and language skills in FEP patients. In addition, lower odds of using adaptive coping were related to higher levels of depressive symptoms in the group of patients. Adaptive coping was associated with better global cognitive performance in healthy controls. Our results indicate that cognitive impairments, especially worse performance of visuospatial/constructional abilities and language skills, might be related to the preference of maladaptive coping strategies. Lower odds of using adaptive coping styles might be associated with more severe depressive symptomatology.

Elevated allostatic load early in the course of schizophrenia

Stress plays a significant role in schizophrenia from disease onset to exacerbation of psychotic symptoms. Allostatic load (AL) is a measure of cumulative stress to the organism. This study is an extension of our previous work on AL and its relationship to brain structures. Here, we further determined whether elevated AL is a function of illness chronicity, or if it is already present early in the course of schizophrenia. AL was compared in schizophrenia patients early in the illness (within 5 years of disease onset), patients with chronic schizophrenia (more than 5 years of illness), and two groups of healthy controls that were age-and sex-matched to the two patient groups. This work is presented with an expanded sample and includes about two-thirds of the participants who were previously reported. We found that patients with early psychosis had significantly elevated AL score compared with their age-matched controls (p = 0.005). Chronic course patients also had elevated AL compared with age-matched controls (p = 0.003). Immune and stress hormone AL subcomponents were nominally higher in early-stage patients compared with controls (p = 0.005 and 0.04, respectively). Greater AL was also associated with more severe positive psychotic symptoms in early-stage patients (r = 0.54, p = 0.01). Elevated levels of allostatic load are already present in the early years of the schizophrenia illness, particularly in patients with more severe psychotic symptoms. AL may be a useful evaluation for the need of early intervention on psychosomatic comorbidity.

Allostatic load and disordered white matter microstructure in overweight adults

Overweight and stress are both related to brain structural abnormalities. The allostatic load model states that frequent disruption of homeostasis is inherently linked to oxidative stress and inflammatory responses that in turn can damage the brain. However, the effects of the allostatic load on the central nervous system remain largely unknown. The current study aimed to assess the relationship between the allostatic load and the composition of whole-brain white matter tracts in overweight subjects. Additionally, we have also tested for grey matter changes regarding allostatic load increase. Thirty-one overweight-to-obese adults and 21 lean controls participated in the study. Our results showed that overweight participants presented higher allostatic load indexes. Such increases correlated with lower fractional anisotropy in the inferior fronto-occipital fasciculi and the right anterior corona radiata, as well as with grey matter reductions in the left precentral gyrus, the left lateral occipital gyrus, and the right pars opercularis. These results suggest that an otherwise healthy overweight status is linked to long-term biological changes potentially harmful to the brain.

Maternal Preconception Stress Alters Prefrontal Cortex Development in Long-Evans Rat Pups without Changing Maternal Care

Stress during development can shift the typical developmental trajectory. Maternal stress prior to conception has recently been shown to exert similar influences on the offspring. The present study questioned if a consistent maternal stressor prior to conception (elevated platform stress) would impact the pre-weaning development of offspring brain and behavior, and if maternal care was vulnerable to this experience. Adult female Long-Evans rats were subjected to elevated platform stress for 27 days prior to mating with non-stressed males. Maternal care was monitored, and pups were assessed in two tests of early behavioral development, negative geotaxis and open field. Pups were perfused at weaning and their brains were extracted and stained with Cresyl Violet, allowing gross measurements of cortical and subcortical structures and estimates of neuron density. Main findings indicate that a change in prefrontal cortical thickness is evident despite no change in maternal care. Female offspring show a decrease in medial-dorsal thalamus size. The current study failed to find an effect of maternal preconception stress on early behavioral development. These results suggest that the PFC, and likely behavior dependent on the PFC, is vulnerable to maternal preconception stress and that a strong sex effect is evident. Further studies should examine how such offspring fare using a lifespan model and investigate potential mechanisms responsible for these effects.

Decreased use of active coping styles contributes to elevated allostatic load index in first-episode psychosis

Accumulating evidence indicates that stress plays an important role in the development of psychotic disorders. Recent studies have revealed that patients with first-episode psychosis (FEP) present systemic biological dysregulations related to stress-exposure in terms of elevated allostatic load (AL) index. However, the mechanisms underlying this observation remain unknown. Therefore, in this study we aimed to investigate the AL index with respect to stress coping strategies in 36 FEP patients and 31 matched controls. We found significantly higher AL index in FEP patients compared to controls after co-varying for potential confounding factors. Patients with FEP were less likely to use active and task-focused coping. Lower odds of using these coping styles, planning as well as positive reinterpretation and growth were related to higher AL index in FEP patients, but not in controls. Depressive symptoms were associated with lower likelihood of using task-focused coping as well as positive reinterpretation and growth. Additionally, depressive symptoms were related to higher AL index. Finally, depressive symptoms mediated the effects of task-focused coping as well as positive reinterpretation and growth on the AL index. Our results confirm systemic biological dysregulation indexed as AL in FEP patients. Lower odds of using active coping styles might contribute to higher AL index via the mediating effect of depressive symptoms in patients with FEP. Longitudinal studies are required to establish causal inferences between coping styles, depressive symptoms and the AL index in early psychosis.

The first multi-zoo application of an allostatic load index to western lowland gorillas (Gorilla gorilla gorilla)

Vertebrate stress responses are highly adaptive biological functions, maximizing survival probability in life-threatening situations. However, experiencing repeated and/or chronic stressors can generate physiological dysregulation and lead to disease. Because stress responses are multi-systemic and involve a wide range of physiological functions, identifying responses to stressors is best accomplished using integrated biomarker models. Allostatic load, defined as the physiological dysregulation that accumulates over the lifespan due to stressful experiences, is one such model. Allostatic load is measured using allostatic load indices, which are composites of biomarkers from multiple somatic systems. Previously, we reported the use of a 7-biomarker allostatic load index (albumin, CRH, cortisol, DHEA-S, glucose, IL-6, TNF-α) in western lowland gorillas housed at a single zoo. Herein, this index is expanded to examine allostatic load responses to lifetime stressors in gorillas from two additional zoos (n = 63) as well as two pooled samples. The index was created using quartile cut-points for each biomarker. Significant associations were observed between multiple predictor variables and allostatic load, including sex, age, number of stressful events (anesthetic events, zoo transfers, agonistic interactions with wounding, pregnancies), and rearing history (mother-reared, nursery-reared, wild-caught). Additionally, allostatic load was associated with indicators of morbidity (creatinine, cholesterol, triglycerides), age at death, and mortality risk. These results are consistent with those reported in human allostatic load research, suggesting allostatic load indices have potential as an investigative and clinical tool for gorillas and other great apes.

Relationships in Ongoing Structural Maintenances of the Two Cerebral Cortices of an Individual Brain

A human brain has separate left and right cerebral cortices, each of which must be continuously structurally maintained during adulthood. There is no understanding of how ongoing structural maintenances of separate parts of a mature individual brain, including the 2 cortices, are related. To explore this issue, this study used an unconventional N-of-1 magnetic resonance imaging time-series paradigm to identify relationships between maintenances of structural thicknesses of the 2 cortices in an adult human brain over week intervals for 6 months. The results suggest that maintenances of left and right cortical thicknesses were symmetrically related in some, but asymmetrically related in other, respects. For matched times, thickness magnitudes and variations on the 2 sides were positively correlated and appeared to reflect maintenance symmetry. Maintenance relationships also extended from earlier to later times with temporal continuity and apparent “if-then” contingencies which were reflected in symmetry and asymmetry dynamics spanning 1- to 2-week periods. The findings suggest concepts of individual brain cortical maintenance symmetry, asymmetry, and temporal continuity dynamics that have not been previously recognized. They have implications for defining cortical maintenance traits or states and for development of N-of-1 precision medicine paradigms that can contribute to understanding individual brain health.

Allostatic load as a predictor of grey matter volume and white matter integrity in old age: The Whitehall II MRI study

The allostatic load index quantifies the cumulative multisystem physiological response to chronic everyday stress, and includes cardiovascular, metabolic and inflammatory measures. Despite its central role in the stress response, research of the effect of allostatic load on the ageing brain has been limited. We investigated the relation of mid-life allostatic load index and multifactorial predictors of stroke (Framingham stroke risk) and diabetes (metabolic syndrome) with voxelwise structural grey and white matter brain integrity measures in the ageing Whitehall II cohort (N = 349, mean age = 69.6 (SD 5.2) years, N (male) = 281 (80.5%), mean follow-up before scan = 21.4 (SD 0.82) years). Higher levels of all three markers were significantly associated with lower grey matter density. Only higher Framingham stroke risk was significantly associated with lower white matter integrity (low fractional anisotropy and high mean diffusivity). Our findings provide some empirical support for the concept of allostatic load, linking the effect of everyday stress on the body with features of the ageing human brain.

Allostatic load is associated with psychotic symptoms and decreases with antipsychotic treatment in patients with schizophrenia and first-episode psychosis

Current pathophysiological models of schizophrenia suggest that stress contributes to the etiology and trajectory of the disorder. We investigated if allostatic load (AL), an integrative index of neuroendocrine, immune and metabolic dysregulation in response to chronic stress, is elevated in patients with schizophrenia (SCZ) and first-episode psychosis (FEP) and related to psychotic symptoms and social and occupational functioning. Additionally, we assessed the temporal dynamics of AL in response to treatment with second-generation antipsychotics. AL, psychotic symptoms and psychosocial functioning were assessed in a longitudinal design in patients with SCZ (n = 28), FEP (n = 28), and healthy controls (n = 53) at baseline and 6 and 12 weeks after commencement of antipsychotic therapy. AL at baseline was higher in patients with SCZ and FEP relative to controls, but not different between patients with SCZ and FEP. Adjusting for age and smoking, we found that positive symptoms were positively correlated with AL and psychosocial functioning was negatively correlated with AL at trend level. Linear mixed model analysis demonstrated that AL decreased after treatment was commenced in patients with SCZ and FEP between the baseline assessment and the 6 and 12-week follow-up. AL was not predictive of treatment response or symptomatic remission. Our data provide evidence for cumulative physiological dysregulation in patients with SCZ and FEP that is linked to the experience of current positive psychotic symptoms. AL could be a useful tool to monitor biological signatures related to chronic stress and unhealthy behaviors in schizophrenia.

Allostatic Load Is Linked to Cortical Thickness Changes Depending on Body-Weight Status

Objective: Overweight (body mass index or BMI ≥ 25 kg/m²) and stress interact with each other in complex ways. Overweight promotes chronic low-inflammation states, while stress is known to mediate caloric intake. Both conditions are linked to several avoidable health problems and to cognitive decline, brain atrophy, and dementia. Since it was proposed as a framework for the onset of mental illness, the allostatic load model has received increasing attention. Although changes in health and cognition related to overweight and stress are well-documented separately, the association between allostatic load and brain integrity has not been addressed in depth, especially among overweight subjects.

Method: Thirty-four healthy overweight-to-obese and 29 lean adults underwent blood testing, neuropsychological examination, and magnetic resonance imaging to assess the relationship between cortical thickness and allostatic load, represented as an index of 15 biomarkers (this is, systolic and diastolic arterial tension, glycated hemoglobin, glucose, creatinine, total cholesterol, HDL and LDL cholesterol, triglycerides, c-reactive protein, interleukin-6, insulin, cortisol, fibrinogen, and leptin).

Results: Allostatic load indexes showed widespread positive and negative significant correlations (p < 0.01) with cortical thickness values depending on body-weight status.

Conclusion: The increase of allostatic load is linked to changes in the gray matter composition of regions monitoring behavior, sensory-reward processing, and general cognitive function.