Emerging work suggests that affect regulation strategies (e.g., active coping, anger expression) predict disease and mortality risk, with sometimes divergent estimates by sex or education levels. However, few studies have examined potential underlying biological mechanisms. This study assessed the longitudinal association of affect regulation with future allostatic load.
Background: Current pathophysiological models of schizophrenia suggest that stress contributes to the etiology and trajectory of the disorder. We investigated whether cumulative exposure to stress, quantified by allostatic load (AL), an integrative index of immune, metabolic, and neuroendocrine dysregulation, is elevated in patients with schizophrenia (SCZ) and first-episode psychosis (FEP) and related to psychotic symptoms and social and occupational functioning and assessed the temporal dynamics of AL in response to treatment with second-generation antipsychotics. Methods: We assessed AL in a naturalistic study of unmedicated patients with SCZ (n = 28), FEP (n = 28), and healthy controls matched for age and gender (n = 53) at baseline and 6 and 12 weeks after commencement of antipsychotic therapy. Biomarkers for the AL index were selected based on (1) representation of several physiological systems including the cardiovascular, neuroendocrine, immune, and metabolic systems; (2) use in previous AL research; and (3) associations with disease risk. We adopted a scaled AL algorithm whereby each marker proportionally contributes to the overall AL index. Unadjusted and adjusted differences between patients with SCZ, FEP, and controls in AL were tested with ANCOVA, and partial correlations were used to test associations of AL with psychometric variables. Results: AL was higher in patients with SCZ compared to controls (4.91 ± 1.89 vs. 2.87 ± 1.62, P < .001), patients with FEP compared to controls (3.80 ± 1.66 vs. 2.87 ± 1.62, P = .020) but not different between patients with SCZ and patients with FEP (P = .302). Adjusting for age and smoking, we found that positive symptoms were positively correlated with AL across all patients with a psychotic disorder (adjusted R = .520, P < .001) and Global Assessment of Functioning (GAF) scores were negatively correlated with AL at trend level (adjusted R = −.251, P = .070). No significant associations were found for negative symptoms (P = .582). AL decreased after treatment with olanzapine, risperidone, or quetiapine was commenced in patients with SCZ and FEP between the baseline assessment and the 6- and 12-week follow-up. Conclusion: 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 model that takes stress, long-term adaptation, and its failures into account to further understand the pathophysiology of schizophrenia.
<p>Context: The majority of studies find that older adults have worse memory performance than young adults. However, contextual features in the testing environment may be perceived as stressful by older adults, increasing their stress hormone levels. Given the evidence that older adults are highly sensitive to the effects of stress hormones (cortisol) on memory performance, it is postulated that a stressful testing environment in older adults can lead to an acute stress response and to memory impairments.</p> <p>Objective: The current study compared salivary cortisol levels and memory performance in young and older adults tested in environments manipulated to be stressful (unfavourable condition) or not stressful (favourable condition) for each age group.</p> <p>Methods: 28 young adults and 32 older adults were tested in two testing conditions: (1) a condition favouring young adults (constructed to be less stressful for young adults), and (2) a condition favouring older adults (constructed to be less stressful for older adults). The main outcome measure was salivary cortisol levels. Additionally, immediate and delayed memory performances were assessed during each condition.</p> <p>Results: In older adults only, we found significantly high cortisol levels and low memory performance in the condition favouring young adults. In contrast, cortisol levels were lower and memory performance was better when older adults were tested in conditions favouring them. There was no effect of testing condition in young adults.</p> <p>Conclusions: The results demonstrate that older adults’ memory performance is highly sensitive to the testing environment. These findings have important implications for both research and clinical settings in which older adults are tested for memory performance.</p>
Allostatic load is commonly operationalized using a sum-score of high-risk biomarkers. However, this method implies that biomarkers contribute equally to allostatic load, as each is given equal weight. Our goal in this methodological paper is to evaluate this, and complementarily, to identify biomarkers that are most informative and least informative for developing an allostatic load index. Item response theory models provide an alternate approach to calculating the allostatic load score, by treating individual biomarkers (e.g. "items") as indicators of a latent allostatic load construct. Item response theory scores account for the data-driven discriminating power of each biomarker, and an individual's pattern of biomarker responses. To demonstrate feasibility of this approach, we used data from the 2015-2016 National Health Examination and Nutrition Survey (NHANES; N = 3751), with twelve allostatic load biomarkers representing immune response, metabolic function and cardiovascular health. Item response theory models revealed that body-mass-index and C-reactive protein were the most informative biomarkers for allostatic load. Both higher allostatic load sum-score and allostatic load item response theory score were associated with lower socio-economic status (p = 0.008; p<0.001, respectively). Further, both formulations of allostatic load were positively associated with a nine-item depression screener (p<0.001 for both), but only the item response theory score was also positively associated with the impact of depressive symptoms on daily life (p = 0.045). Item response theory scores may be more finely tuned to tease out effects, compared to sum-scores, and also provide more flexibility when there are missing biomarker measurements. Supplemental R code for our approach are included.
