Evaluating the Psychological Impact of War Beyond Conflict Boundaries: Design and Validation of the War Worry Scale and Its Implications for Italian Young Adults' Mental Health

War is a current macro-social stressor whose traumatic impact transcends conflict zones, fostering psychological distress even among populations not directly involved. Ongoing wars in Europe and the Middle East are intensifying fears and anxieties, with negative consequences for mental health, particularly during emerging adulthood (18-30 years). In Italy, research on the indirect psychological effects of war is still limited, partly due to the absence of appropriate assessment tools. To address this gap, the present contribution outlines the development and validation of the War Worry Scale (WWS), a novel instrument based on original narrative materials designed to assess the psychological impact of war among Italian young adults (Studies 1 and 2). A further study (Study 3) investigates the relationships between Worry about War, Anxiety, and Depression, focusing on the mediating role of Intolerance of Uncertainty (IU) and Future Anxiety (FA). In Study 1, 250 young adults (M = 22.58) were recruited to explore the latent structure of the WWS via Exploratory Factor Analysis, leading to the selection of 10 items grouped into two dimensions. Study 2, conducted with an independent sample of 500 participants (M = 22.84), used Confirmatory Factor Analysis to support a second-order hierarchical structure - Worry about War (WW) - with two first-order dimensions: “Worry about the Present” and “Worry about the Future” (5 items each), showing excellent fit indices (CFI = .973; TLI = .965; RMSEA = .059; SRMR = .035). The WWS demonstrated measurement invariance across gender (configural, metric, scalar), high internal consistency as well as solid convergent, divergent, and concurrent validity. In Study 3, a parcel-based Structural Equation Model was tested on a new sample of 460 participants (M = 22.44), revealing a direct effect of Worry about War on Anxiety (p < .05) and confirming the mediating roles of IU and FA in the tested relationships (all p < .001). The model showed good fit indices (CFI = .964; TLI = .952; RMSEA = .064; SRMR = .047). Overall, findings support the WWS as a valid and reliable tool and emphasize the importance of exploring how worry about war impacts young adults’ mental health.