Comparing different operationalizations of allostatic load measured in mid-life and their patterning by race and cumulative life course socioeconomic status

An evaluation of the All of Us Research Program database to examine cumulative stress

OBJECTIVES

To evaluate the NIH All of Us Research Program database as a potential data source for studying allostatic load and stress among adults in the United States (US).

MATERIALS AND METHODS

We evaluated the All of Us database to determine sample size significance for original-10 allostatic load biomarkers, Allostatic Load Index-5 (ALI-5), Allostatic Load Five, and Cohen's Perceived Stress Scale (PSS). We conducted a priori, post hoc, and sensitivity power analyses to determine sample sizes for conducting null hypothesis significance tests.

RESULTS

The maximum number of responses available for each measure is 21 participants for the original-10 allostatic load biomarkers, 150 for the ALI-5, 22 476 for Allostatic Load Five, and n = 90 583 for the PSS.

DISCUSSION

The NIH All of Us Research Program is well-suited for studying allostatic load using the Allostatic Load Five and psychological stress using PSS.

CONCLUSION

Improving biomarker data collection in All of Us will facilitate more nuanced examinations of allostatic load among US adults.

Associations of childhood, adolescence, and midlife cognitive function with DNA methylation age acceleration in midlife

Prior studies showed increased age acceleration (AgeAccel) is associated with worse cognitive function among old adults. We examine the associations of childhood, adolescence and midlife cognition with AgeAccel based on DNA methylation (DNAm) in midlife. Data are from 359 participants who had cognition measured in childhood and adolescence in the Child Health and Development study, and had cognition, blood based DNAm measured during midlife in the Disparities study. Childhood cognition was measured by Raven's Progressive Matrices and Peabody Picture Vocabulary Test (PPVT). Adolescent cognition was measured only by PPVT. Midlife cognition included Wechsler Test of Adult Reading (WTAR), Verbal Fluency (VF), Digit Symbol (DS). AgeAccel measures including Horvath, Hannum, PhenoAge, GrimAge and DunedinPACE were calculated from DNAm. Linear regressions adjusted for potential confounders were utilized to examine the association between each cognitive measure in relation to each AgeAccel. There are no significant associations between childhood cognition and midlife AgeAccel. A 1-unit increase in adolescent PPVT, which measures crystalized intelligence, is associated with 0.048-year decrease of aging measured by GrimAge and this association is attenuated after adjustment for adult socioeconomic status. Midlife crystalized intelligence measure WTAR is negatively associated with PhenoAge and DunedinPACE, and midlife fluid intelligence measure (DS) is negatively associated with GrimAge, PhenoAge and DunedinPACE. AgeAccel is not associated with VF in midlife. In conclusion, our study showed the potential role of cognitive functions at younger ages in the process of biological aging. We also showed a potential relationship of both crystalized and fluid intelligence with aging acceleration.

Racial Disparities in COVID-19 Severity Are Partially Mediated by Chronic Stress-Evidence from a Large Integrated Healthcare System

BACKGROUND

Racial and ethnic minorities have experienced a disproportionate burden of severe COVID-19. Whether chronic stress, also disproportionately experienced by racial and ethnic minorities, explains this excess risk is unknown.

METHODS

We identified 9577 adults (≥ 18 years) diagnosed with COVID-19 from January 1, 2020, through September 30, 2021, enrolled in Kaiser Permanente Georgia (KPGA) with complete biomarker data. Self-reported race (Black or White) was defined from electronic medical records. Chronic stress, defined as allostatic load (AL), a composite score (scale 0-7) based on seven cardio-metabolic biomarkers, was categorized as below (low AL) or above (high AL) the median. Severe COVID-19 was defined as hospitalization or mortality within 30 days of COVID-19 diagnosis. The association between race, AL, and severe COVID-19 was assessed using multivariable Poisson regression. The mediating effect of AL was assessed using the Valeri and VanderWeele method. All results were expressed as risk ratios (RRs) with 95% confidence intervals.

RESULTS

Overall, Black (vs. White) KPGA members had an 18% excess risk of AL (RR: 1.18, 95%CI: 1.14-1.23) and a 24% excess risk of severe COVID-19 (RR: 1.24, 95%CI: 1.12, 1.37). AL explained 23% of the Black-White disparities in severe COVID-19.

CONCLUSIONS

In our study, chronic stress, characterized by AL, partially mediated Black-White disparities in severe COVID-19 outcomes.

Sense of purpose in life and allostatic load in two longitudinal cohorts

OBJECTIVE

Sense of purpose in life has been linked with better physical health, longevity, and reduced risk for disability and dementia, but the mechanisms linking sense of purpose with diverse health outcomes are unclear. Sense of purpose may promote better physiological regulation in response to stressors and health challenges, leading to lower allostatic load and disease risk over time. The current study examined the association between sense of purpose in life and allostatic load over time in adults over age 50.

METHODS

Data from the nationally representative US Health and Retirement Study (HRS) and English Longitudinal Study of Ageing (ELSA) were used to examine associations between sense of purpose and allostatic load across 8 and 12 years of follow-up, respectively. Blood-based and anthropometric biomarkers were collected at four-year intervals and used to compute allostatic load scores based on clinical cut-off values representing low, moderate, and high risk.

RESULTS

Population-weighted multilevel models revealed that sense of purpose in life was associated with lower overall levels of allostatic load in HRS, but not in ELSA after adjusting for relevant covariates. Sense of purpose in life did not predict rate of change in allostatic load in either sample.

CONCLUSIONS

The present investigation supports sense of purpose predicting preserved differentiation of allostatic regulation, with more purposeful individuals demonstrating consistently lower allostatic load over time. Persistent differences in allostatic burden may account for divergent health trajectories between individuals low and high in sense of purpose.

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.

Female fecundability is associated with pre-pregnancy allostatic load: Analysis of a Chinese cohort

INTRODUCTION

Allostatic load (AL) is a practical index that reflects multi-system physiological changes which occur in response to chronic psychosocial stress. This study investigated the association between female pre-pregnancy allostatic load and time to pregnancy.

MATERIAL AND METHODS

We enrolled 444 women who met the inclusion criteria and were attempting to achieve pregnancy. Their allostatic load scores at baseline were evaluated by nine indicators (systolic blood pressure, diastolic blood pressure, fasting plasma glucose, plasma cortisol, noradrenaline, interleukin-6, hypersensitive C-reactive protein, high density lipoprotein cholesterol and body mass index). The participants were followed up and their pregnancy outcome ascertained 1 year later; we then calculated time-to-pregnancy. Cox models were used to estimate fecundability ratios and their 95% confidence intervals (95% CI) for different allostatic load scores.

RESULTS

The median allostatic load score was 1 with a range of 0-6. The females were divided into four groups according to allostatic load score: group A (allostatic load = 0, 150/444, 33.8%), group B (allostatic load = 1-2, 156/444, 35.1%), group C (allostatic load = 3-4, 100/444, 22.5%) and group D (allostatic load = 5-6, 38/444, 8.6%). The cumulative pregnancy rate over 12 months for the four groups (A-D) was 55.4%, 44.5%, 50.9% and 26.9%, respectively (log-rank test, p = 0.042). After adjusting for potential confounding factors, group D showed a 59% reduction of fecundability compared with group A (fecundability ratio = 0.41, 95% CI 0.21-0.83).

CONCLUSIONS

Women with a higher allostatic load score may have lower fecundability. Our findings suggest that the assessment of allostatic load during pre-conception consultation would be highly prudent.

The Association between Multiple Per- and Polyfluoroalkyl Substances' Serum Levels and Allostatic Load

Background/Objective: This study aimed to explore the association between allostatic load (AL), an index of chronic stress, with nine per- and polyfluoroalkyl substances (PFASs), a group of organic compounds used in commercial and industrial applications. The PFASs explored were perfluorohexane sulfonic acid (PFHS), perfluorodecanoic acid (PFDE), perfluorobutane sulfonic acid (PFBS), perfluoroheptanoic acid (PFHP), perflurododecanoic acid (PFDO), perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS). This study was performed to better understand the association between PFASs and AL, which may be a mediator of several diseases. Methods: This study was performed on adults aged 20 and older, using the National Health and Nutrition Examination Survey (NHANES) 2007−2014 data. AL was calculated as a cumulative index of ten biomarkers from the cardiovascular, inflammatory, and metabolic system, which was dichotomized into high risk (assigned a value of 1) or low risk (assigned a value 0) depending on if the index value was ≥3 (chronic physiological stress) or <3 (less stressed). In this study, PFASs and covariates such as age, gender, ethnicity, alcohol consumption, smoking, and physical activity were explored using descriptive statistics and logistic regression modeling. Results: The results indicated that in adults, AL was more elevated in men as compared to women, in those aged ≥60 years, and varied by ethnicity. For instance, non-Hispanic Blacks had higher AL levels (mean of 3.92) compared to other ethnicities. A significant number of the participants tested for PFBS, PFHP, PFDO were below the LOD and thus these PFASs were excluded from the analysis. Our analysis demonstrated multicollinearities between variables such as PFNA, PFOS, and PFOA with variance inflation factor (VIF) values of 6.197, 6.212, and 5.139, respectively. Thus, PFASs were analyzed individually and adjusted for age, gender, ethnicity, physical activity, smoking, and alcohol consumption. The results indicated a statistically significant positive association between AL and most of the PFASs, except PFUA which was not statistically significant with a p value of 0.531. Conclusions: The findings of this study suggest that exposure to PFDE, PFNA, PFOS, PFOA, and PFHS are associated with AL when adjusted for age, gender, ethnicity, alcohol consumption, smoking, and physical activity. Future studies looking to model the effects of these factors together must consider their relationship with each other and choose different analytical approaches.