Psychometric Properties and Measurement Invariance of the International Adjustment Disorder Questionnaire (IADQ): Reliability, Validity, and Factor Structure Among Emerging Adults Exposed to Psychological Stressors in India

Abstract Adjustment disorder is typically considered a mild mental health condition; however, if left untreated, it can progress to more severe psychiatric disorders. The International Adjustment Disorder Questionnaire (IADQ) was developed to assess adjustment disorders and has been validated in various cultural contexts. Nevertheless, no prior studies have examined the measurement invariance of the IADQ across gender, especially given that men and women respond differently to stressful situations. Additionally, the psychometric properties of the IADQ have not been examined in Indian samples. Therefore, the present study evaluated the psychometric properties and measurement invariance of the IADQ across gender in a sample of 1,069 emerging adults, aged 18–29 years (Mage = 21.59, SDage = 2.65; 56.5% female). Confirmatory factor analysis supported the two-factor structure of the IADQ, comprising preoccupation and failure to adapt. Measurement invariance analysis demonstrated full configural, metric, scalar, and strict invariance across gender. The IADQ demonstrated good internal consistency (α = .817–888, ω = .819 − .889). Furthermore, the IADQ showed significant positive associations with co-occurring psychopathology and negative correlations with positive mental health indicators. Overall, these findings support the reliability and validity of the IADQ and its suitability for gender comparisons among emerging adults.