Reduced serum Klotho in chronic schizophrenia: diagnostic value and association with cognitive impairment.

OBJECTIVE: To investigate the correlation between serum Klotho levels and cognitive function in individuals with chronic Schizophrenia (SZ). METHODS: A total of 108 patients diagnosed with chronic SZ and 83 age-matched healthy controls were recruited from four psychiatric specialist hospitals in Lianyungang from January to December 2024. Serum Klotho levels were measured using an enzyme-linked immunosorbent assay. Psychopathology and cognitive function were assessed using the Positive and Negative Syndrome Scale and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively. Kendall's tau-b correlation analyses were conducted to assess the associations between serum Klotho levels and cognitive function. RESULTS: Compared with healthy controls, patients with SZ had significantly lower serum Klotho levels (233.61 ± 50.35 pg/mL vs 347.11 ± 62.64 pg/mL, P < 0.001). They also showed significantly lower total scores in the overall cognitive performance and across the RBANS sub-domains (all P < 0.01). ROC curve analysis revealed that serum Klotho levels discriminated patients with schizophrenia from healthy controls with an AUC of 0.914 (95% CI: 0.876-0.951), with an optimal cutoff of 268.25 pg/mL (sensitivity 76.9%, specificity 89.2%). After Bonferroni correction, serum Klotho levels were positively correlated with immediate memory in patients (corrected P = 0.010). No significant associations between serum Klotho levels and cognitive measures were found in healthy controls. CONCLUSION: Patients with chronic SZ have lower serum Klotho levels and show cognitive impairment, and Klotho levels are specifically associated with immediate memory in this population.