Developmental trajectories in psychiatric disorders: does substance/alcohol use moderate the effects of affective temperaments as moderators of age at onset? A study in post-acute, hospitalized patients with psychotic or DSM-5 bipolar or major depressive disorders

Age-at-onset (AAO) affects psychiatric disorder outcome; substance (SUDs) or alcohol use disorders (AUDs) may influence their onset. Affective temperaments may affect early AAO and drug-use proneness. Objectives: To investigate whether SUD/AUD moderated temperamental effects in determining AAO of mental disorders. Methods: We included 300 post-acute inpatients with schizophrenia-spectrum and other psychotic (SSOPDs), major depressive (MDD) or bipolar (BD) disorders (168 men; mean age, 40.63 years ± 11.82 men, 43.21 years ± 12.69 women) with (N = 110) or without (N = 190) SUD/AUD. Patients completed cross-sectionally TEMPS-A. We carried moderation analysis with each regression-significant TEMPS temperament as independent variable, SUD/AUD presence/absence as dichotomous moderator, and AAO as dependent variable. Significance was set at p < 0.05. Results: AAO was lower in patients with SUD/AUD diagnosis than in patients without (23.74 ± 10.09 vs. 27.73 ± 10.35, respectively, p = 0.001, η2 = 0.034). SUD/AUD patients scored higher on the hyperthymic (10.22 ± 4.08, p < 0.001, η2 = 0.069) and irritable (8.26 ± 4.69, p < 0.01, η2 = 0.026) temperaments than nonSUD/AUD patients. Moderation analysis showed only direct effects of irritable (β = -0.55, p < 0.005) and hyperthymic (β = -0.95, p < 0.001) temperaments on AAO and no significant SUD/AUD and interaction effects. Limitations. Cross-sectional design. Conclusions: When irritable and hyperthymic traits prevail over other temperaments, AAO is earlier in SSOPDs, MDD, and BD. SUD/AUD presence/absence does not moderate the relationship between temperament and AAO.