Psychometric properties and factor structure of the cognitive distortions questionnaire (CD Quest)

Cognitive distortions are central to contemporary clinical theory and practice, yet psychometric evidence for the Persian Cognitive Distortions Questionnaire (CD-Quest) has been limited. This study evaluated the psychometric properties of the Persian CD-Quest in Iranian adults. Participants (N = 567; 18–60 years) were recruited in 2023 from Arak, Iran, using quota-based stratification by gender and recruitment site (ten high-traffic urban locations, e.g., city bazaar, main square, university, service centers). Measures included the CD-Quest, Automatic Thoughts Questionnaire, and General Health Questionnaire. Analyses combined Classical Test Theory (CTT) and Item Response Theory (IRT). CTT results showed acceptable item–total correlations (≥ .30). IRT supported unidimensionality and favored the generalized partial credit model; item parameters (discrimination and ordered thresholds) were satisfactory. The test information function indicated greatest precision at moderate-to-high levels of the latent trait (peak around θ ≈ 1.70; high-information band θ ≈ 0.34–3.02); marginal reliability was ρ = .701. Gender-based DIF (Wald/Lord χ 2 , Holm–Bonferroni) was not detected, supporting item-level measurement invariance (women vs. men). Findings suggest the Persian CD-Quest was psychometrically sound and informative for clinical screening and research in Iranian adults, thereby advancing cross-cultural assessment of self-related distorted thinking within Beck’s cognitive framework while enabling valid comparisons across gender. • Dysfunctional schemas from previous life experiences create distorted cognitions. • Cognitive distortions in the form of automatic thoughts or temporary negative mental events affect emotional and motivational systems. • The Cognitive Distortions Questionnaire is a valid tool for quantitative assessment in clinical follow-up, and this study aimed to develop this questionnaire for the Iranian community. • A single-factor questionnaire that can be used in laboratory, clinical, and therapeutic research settings by researchers, counselors, and therapists in the Persian-speaking community.