Increased risk of fourteen mental disorders in people with dissociative experiences: A nationwide population-based retrospective cohort study.

OBJECTIVE: Dissociation represents a significant yet underrecognized public health challenge. Over the past two decades, research has increasingly demonstrated a high co-occurrence rate between dissociation and various mental disorders. However, the specific patterns of association between dissociation and these disorders remain ambiguous due to the limited representative data on co-experienced outcomes. Moreover, the extent to which dissociation contributes to the overall burden of mental disorders remains unclear. Leveraging the largest population-based, cross-sectional dataset on dissociation to date, this study aims to elucidate the patterns of association between the severity of dissociation and fifteen mental disorders, as well as to preliminarily evaluate the extent to which dissociation accounts for the associations between psychiatric morbidity, sociodemographic factors, and broader health outcomes.

METHODS: This study used data from the National Co-morbidity Survey-Replication (NCS-R), a comprehensive database on dissociation in the United States. Prevalence rates were compared across different dissociation severity groups. Odds ratios (ORs) and their confidence intervals (CIs) were calculated to assess the associations. Mediation analyses were conducted to estimate the proportion of the total association accounted for by the indirect pathway through dissociation severity across three frameworks: (I) associations between individual DSM-IV disorders and the 'leave-one-out' mental health burden; (II) the link between mental health burden and three general health outcomes (suicidal ideation, chronic conditions, and functional impairment); and (III) associations between demographic characteristics and mental health burden. All models were adjusted for sociodemographic factors and BMI, with leave-one-out outcomes employed to preclude mathematical coupling.

RESULTS: The study included 6644 adults, with 23·8% experiencing dissociation (ED), 3·2% experiencing mild pathological dissociation (MPD), and 0·9% experiencing severe pathological dissociation (SPD). Across all levels of dissociation severity, female, younger age, shorter education years, never married, not in the labor force, belonging to the unhealthy BMI group, and lower income-to-needs ratio were associated with higher prevalence rates (Ps < 0·0001). Following adjustment for nine sociodemographic covariates, dissociation severity demonstrated significant associations with 14/15 mental disorders assessed, with the sole exception of anorexia (across all severity levels Ps > 0·40). The adjusted ORs for these 14 disorders ranged from 0·192 to 1·815 (95% CIs: 0·093-1·579, 0·381-2·429). While these associations remained largely extant, they were attenuated upon further adjustment for the comorbid presence of the remaining 14 mental disorders (adjusted ORs: 0·401-1·510, 95% CIs: 0·247-1·266, 0·651-1·733). Also, dissociation severity was significantly associated with mental health burden (adjusted ORs: 0·265-1·983, 95% CI: 0·172-2·217). More notably, dissociation severity accounted for significant proportions of the associations across three pathways: (I) between 14/15 individual mental disorders and mental health burden (6%-40%, all Ps < 0·01); (II) between demographic factors and mental health burden (8% for age and -14% for marital status, Ps < 0·001); and (III) between mental health burden and secondary outcomes, including suicidal ideation, cumulative chronic physical conditions, and functional impairment (6%-11%; all Ps < 0·001).

CONCLUSIONS: This study provides robust empirical evidence for that dissociation severity is a transdiagnostic marker associated with the cumulative mental health burden and shows transdiagnostic associations although attenuated by other comorbid lifetime psychiatric disorders. It highlights that pathological dissociation accounts for a substantial proportion of the statistical association between specific mental disorders/high risk sociodemographic and cumulative mental health burden. Furthermore, dissociation serves as a key indirect pathway linking cumulative mental health burden to boarder health outcomes. These findings underscore the importance of integrating dissociative symptom screening into public health frameworks to improve early prevention and targeted intervention strategies for susceptible population.