STUDY DESIGN: Retrospective cohort study.

OBJECTIVES: To investigate a possible linkage between idiopathic scoliosis (IS) and schizophrenia in an adolescent population.

SUMMARY OF BACKGROUND DATA: There is an interesting link between schizophrenia and idiopathic scoliosis: schizophrenia is a disturbance of mental equilibrium, and scoliosis of physical equilibrium, both are multifactorial, genetically determined, start at a young age, and brain development is thought to play a role. Furthermore, both may be presenting symptoms of the genetic disorder 22q11 deletion syndrome. This study poses the question whether these two poorly understood disorders are related.

METHODS: A retrospective cohort study was conducted and consisted of 3,702 Swedish adolescents, collected from the National Patient Register, that underwent inpatient care for IS during 1997-2015. These were matched by age, sex, and date of diagnosis to 370,200 controls, collected from Swedish population data, and then followed up in the National Patient Register to identify in- and outpatient care for schizophrenia diagnosis. Follow-up time was calculated from first IS diagnosis date until date of schizophrenia diagnosis or end of follow-up. Cox proportional regression analysis was performed to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for being diagnosed with schizophrenia.

RESULTS: Over a median follow-up time of 9.5 years, 0.7% of patients with IS developed schizophrenia versus 0.5% of controls (p = .04). The risk of schizophrenia was significantly higher in patients with IS (HR, 1.52; 95% CI, 1.03-2.23). Using only hospitalized schizophrenia as event, the prevalence for schizophrenia was 0.5% versus 0.3% (p ≤.01; HR, 1.83; 95% CI, 1.17-2.84).

CONCLUSION: This study suggests that patients with IS have increased risk of schizophrenia. Dissatisfaction with one's physical appearance might lead to psychological distress and provoke mental illness in predisposed persons. Alternatively, these two disorders may share a common genetic background.

LEVEL OF EVIDENCE: Level 2B.