Schizophrenia spectrum disorder contributes significantly to allostatic load early in the disease course, according to a study recently published in Translational Psychiatry. Despite small individual increases in metabolic, cardiovascular, immune hormone, and stress hormone measures, the sum of these factors comprises allostatic load and was significant.
The sample in this study was composed of 58 individuals with schizophrenia spectrum disorders (48 of whom had schizophrenia and 10 who had schizoaffective disorder) as well as 34 healthy controls matched for age and sex. The study group was divided into 21 individuals who had been diagnosed within the past 5 years (early group) and 37 who had been diagnosed over 5 years previously (chronic).
Allostatic load was measured using 13 biomarkers, for which individual values of at least the 75th percentile were assigned a score of 1 for their corresponding biomarkers. Measures largely adhered to the Kolmogorov-Smirnov tests’ definition of normal distribution. Single-variable ANOVAs were used to compare differences in allostatic load between the study and control groups, with Bonferroni corrections used for analyses of allostatic load subcomponents (threshold P <.006 for significance [(0.05/4 subcomponents x 2 age cohorts]).
Those in the early group showed significantly higher allostatic load than their corresponding controls (3.39 (mean 2.12) vs 1.81 (1.33); F(1,33)=6.22; P =.018), even when sex and age were taken as covariates (F=9.17; P =.005). Those in the chronic group showed similarly higher allostatic load than matched controls (6.14 (2.82) vs 4.14 (2.31); F(1,55)=7.34; P =.009), which increased with adjustments for sex and age (F=9.40; P =.003).
Individuals in the early group showed higher levels of immune (P =.005) and stress (P =.04) hormones than controls. Early stage patients with a higher allostatic load also showed more positive symptoms of psychosis (R=0.54; P =.01) than did the chronic group (R=0.19; P =.29).
The study researchers concluded that there is “a significantly elevated [allostatic load] even in the first 5 years of the illness course of [schizophrenia spectrum disorder]. We found that subcomponents separately measuring immune, stress hormone, cardiovascular or metabolic factors were only weakly to modestly elevated in schizophrenia, but the overall [allostatic load] metric that aggregates these components yielded significant disease effects even with a modest sample of early-stage young patients.”
Disclosure: L. Elliot Hong has received or is planning to receive research funding or consulting fees from Mitsubishi, Neuralstem, Taisho Pharmaceutical, Heptares, and Pfizer.
Savransky A, Chiappelli J, Fisseha F, et al. Elevated allostatic load early in the course of schizophrenia. Transl Psychiatry. 2018;8(1):246.
[S1]Probably my lack of understanding here but did this mean everything above .006 was not significant, so much of the P values in the paragraph below???