Idiographic Modeling of Loneliness: Testing a Theory of Social Homeostasis

/ABSTRACT Loneliness, characterized by the subjective feeling of social disconnection, has significant adverse effects on physical and mental health, including increased risks of premature death, anxiety, depression, and suicide. These consequences are particularly severe among individuals with serious mental illness (SMI), where over 80% report loneliness, and individuals die 15 to 25 years earlier than those in the general population. Current interventions for loneliness in SMI lack broad efficacy and are hindered by a lack of theoretical guidance and a one-size-fits-all approach, failing to address individual (idiographic) differences effectively. This project proposes a novel, theory-informed approach to understanding idiographic mechanisms of loneliness among SMI populations. It is based on the social homeostasis theory, which posits that loneliness results from deficits in social utility, a measure of the fulfillment of social needs. The theory suggests that both the quality and quantity of social interactions contribute to social utility, and discrepancies between actual and preferred states of these interactions lead to loneliness. This research aims to employ intensive longitudinal data collection on daily social experiences of individuals with SMI to model social utility ideographically. The project's aims are to, at the individual level, (1) characterize the heterogeneity of relationships between social utility and loneliness using individual connectivity networks produced with group iterative multiple model estimation, (2) establish extent to which decreases in social utility relate to increases in loneliness by applying response surface analysis within individuals, and (3) clarify the temporal dynamics between these constructs using time-varying network modeling and differential time-varying effects modeling for each participant. The study uses two samples of ecological momentary assessment (EMA) data: the first sample utilizes existing data from SMI patients to explore the theorized relationships in SMI directly. The structure of this existing data will allow for analysis of Aim (1) while a second, non-SMI sample is recruited online. The non-SMI sample will be enriched for loneliness and schizotypal personality traits to test and develop models of social utility more comprehensively. This second set of data is designed to be analyzed for all Aims, and results will generate hypotheses for similar research applied directly to SMI in future studies. By developing idiographic modeling techniques to study social utility, this research aims to advance personalized understanding of the heterogeneity of mechanisms to loneliness in SMI. This work not only progresses the field of clinical psychology by addressing a significant gap in the understanding and eventual treatment of loneliness among those with SMI but also enhances the researcher's skills in idiographic science through mentored training in sophisticated modeling techniques, thus empowering an independent program of future research investigating personalized treatment mechanisms for loneliness in SMI. Project Number: 1F31MH139310-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Mental Health (NIMH) | Principal Investigator: Joseph Maimone | Institution: BOSTON UNIVERSITY (CHARLES RIVER CAMPUS), BOSTON, MA | Award Amount: $42,144 | Activity Code: F31 | Study Section: Special Emphasis Panel[ZRG1 F16-D (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11242694