The Mental Health Profile of Borderline Intellectual Functioning: A Systematic Review

Objective: Psychiatric morbidity patterns and associated outcomes among individuals with borderline intellectual functioning (BIF) remain poorly characterized. This systematic review aims to examine mental health outcomes in BIF populations compared to individuals with normal intellectual functioning and those with intellectual disability (ID). Methods: A systematic literature search was conducted across the PubMed, Web of Science, PsycInfo, and ERIC databases from inception to January 2025 using comprehensive search terms for BIF. Studies were included in this analysis if they examined individuals with intelligence quotient (IQ) 71–84 and reported mental health outcomes. Data extraction focused on subjective well-being, psychopathology prevalence, and comparative analyses. Quality assessment utilized the Mixed Methods Appraisal Tool. Results: Forty-five studies encompassing 93,396 individuals with BIF were included. Individuals with BIF demonstrated significantly elevated psychiatric morbidity compared with average IQ populations across multiple domains including anxiety, mood, personality, and neurodevelopmental disorders. Mental health outcomes of BIF individuals typically fell intermediate to those observed in normal IQ and mild ID populations. Conclusion: Individuals with BIF represent a vulnerable population with substantially elevated mental health risks, yet remain inadequately differentiated from adjacent cognitive groups. The field requires specialized clinical attention, educational support, and targeted interventions to address their unique mental health challenges and improve outcomes.