Fatigue and negative symptoms in schizophrenia spectrum disorders: a PRISMA-ScR compliant scoping review of the literature

Introduction Fatigue is a prevalent and disabling symptom in schizophrenia-spectrum psychotic disorders (SSPD), yet its relationship with negative symptoms (NS), such as apathy and anhedonia, remains underexplored. This scoping review was conducted following PRISMA-ScR guidelines to identify the extent and characteristics of research on this association and to map existing knowledge gaps.Method A scoping review protocol was registered on OSF, and systematic searches were conducted across PubMed, Web of Science, Scopus, PsycINFO, and gray literature sources. Studies of all designs, including narrative reviews, were eligible. No restrictions were placed on language or publication date. Ten studies met the inclusion criteria.Results Fatigue was highly prevalent among individuals with SSPD (54–68%), with significant associations observed between fatigue and NS, including anhedonia and affective flattening. Cognitive and social fatigue emerged as more consistently relevant dimensions, while physical fatigue showed weaker associations. Some studies proposed that fatigue could function as an organizing factor within the symptom structure of schizophrenia or serve as a marker of illness severity, though such classifications remain theoretically speculative. No specific interventions targeting fatigue in SSPD were identified.Conclusions This review provides a descriptive mapping – not a critical synthesis – of a highly fragmented and underdeveloped field. The literature reflects substantial conceptual, instrumental, and clinical gaps in understanding fatigue in SSPD. Future studies should develop validated assessment tools tailored to this population and explore interventions targeting cognitive and social fatigue to improve functional outcomes and quality of life.