Alexithymia in schizophrenia spectrum disorders and dissociative disorders: two meta-analytic reviews.

Schizophrenia-spectrum disorders (SSDs) and dissociative disorders (DDs) often co-occur, and both show emotion processing deficits. Alexithymia-comprising difficulty identifying feelings (DIF), difficulty describing feelings (DDF), and externally oriented thinking (EOT)-is considered a shared vulnerability factor, yet the relative prominence of each facet within and across these disorders remains uncertain. The current two meta-analyses synthesised severity of overall alexithymia and its facets in SSDs (Meta-analysis 1) or DDs (Meta-analysis 2) compared to psychiatrically healthy controls. A preregistered search of PsycINFO, PubMed, and Embase (1970-31 December 2024) identified adult case-control studies. Pooled Hedges' g values were estimated with random-effects meta-analysis models, then compared across diagnoses (moderator analyses) with mixed-effects meta-analysis models. Meta-analysis 1 pooled 27 SSD studies (1477 patients, 1249 controls). Meta-analysis 2 pooled 30 DD studies (842 patients, 796 controls). Both patient groups scored higher than controls on overall alexithymia and all facets. In SSDs, DIF showed the largest group effect (g = 0.894; CI 0.667-1.122), whereas DDF (g = 0.622; CI 0.468-0.775) and EOT (g = 0.585; CI 0.400-0.770) showed moderate effects. In DDs, both DIF (g = 1.311; CI 0.991-1.632) and DDF (g = 0.954; CI 0.707-1.202) showed large effects, whereas EOT (g = 0.427; CI 0.163-0.690) showed a small-to-moderate effect. Between the disorder groups, after removing extreme effects, DDs exhibited greater DIF and DDF than SSDs, whereas SSDs showed higher EOT. Heterogeneity was moderate-to-high, and publication bias was possible in SSD studies. Alexithymia is a significant transdiagnostic deficit, but its facet profiles differ between SSDs and DDs. Emotion-focused interventions should therefore target facet-specific deficits prominent to each disorder group.