Cumulative stress pathophysiology in schizophrenia as indexed by allostatic load

Abstract

The etiopathophysiology of schizophrenia has long been linked to stress and the influence of stress is important in all stages of the illness. Previous examinations of perceived stress and acute stress responses may not capture this longitudinal stress pathophysiology. We hypothesized that the cumulative negative effects of stress, indexed by allostatic load (AL), would be elevated in schizophrenia, and that the AL paradigm would be relevant to our understanding of pathophysiology in schizophrenia. We assessed allostatic load in 30 patients with schizophrenia (SZ; mean age = 33; 17 males) and 20 healthy controls (HC; mean age = 35; 12 males) using 13 cardiovascular, metabolic, neuroendocrine and immune biomarkers. Participants' perceived stress over the past month, functional capacity and psychiatric symptoms were also measured. Controlling for age, SZ had significantly higher AL as compared to HC (p = 0.007). Greater AL was present in both early course and chronic SZ, and was associated with reduced functional capacity (p = 0.006) and more psychotic symptoms (p = 0.048) in SZ. Current level of perceived stress was not significantly elevated in SZ or associated with AL in either group. The higher AL found in SZ may reflect increased bodily "wear and tear", possibly caused by more chronic stress exposure or maladaptive responses to stress over time, although additional research is required to differentiate these causes. The higher AL is similarly present in early and chronic SZ, suggesting primary maladaptive stress physiology rather than secondary effects from medications or chronic illness.