Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in the development of psychosis and subthreshold psychotic symptoms commonly referred to as psychotic-like experiences (PLEs). The exact mechanisms linking the HPA axis responses with the emergence of PLEs remain unknown. The present study aimed to explore real-life associations between stress, negative affect, salivary cortisol levels (a proxy of the HPA axis activity) as well as PLEs together with their underlying cognitive biases (i.e., threat anticipation and aberrant salience). The study was based on the experience sampling method scheduled over 7 consecutive days in the sample of 77 drug-naïve, young adults (18-35 years). The saliva samples were collected with each prompt to measure cortisol levels. A temporal network analysis was used to explore the directed associations of tested variables. Altogether, 3234 data entries were analyzed. Data analysis revealed that salivary cortisol levels did not directly predict next-moment fluctuations of PLEs. However, higher salivary cortisol levels were associated with higher next-moment levels of PLEs through the effects on threat anticipation and negative affect. In turn, PLEs appeared to predict cortisol levels through the effects on negative affect and event-related stress. Negative affect and threat anticipation were the most central nodes in the network. There might be bidirectional associations between the HPA axis responses and PLEs. Threat anticipation and negative affect might be the most important mediators of these associations. Interventions targeting these mediators might hold promise for disrupting the connection between the HPA axis dysregulation and PLEs.
Keywords: cortisol levels; ecological momentary assessment; hypothalamic–pituitary–adrenal axis; psychosis; psychotic-like experiences.