Telomere shortening is strongly associated with higher mortality rates and has been shown in a number of age-related diseases, such as cardiovascular disorders, diabetes mellitus, Alzheimer's disease, and psychiatric disorders. Oxidative stress is known to induce DNA breaks and genome instability. Telomeric DNA rich in guanosine is particularly sensitive to such oxidative damages. Psychosis is associated with a disequilibrium between free radical production and antioxidative defense. Although telomere attrition has been demonstrated in schizophrenia, no relationship has been reported between telomere length and severity of schizophrenia.
The aim of the present study was to identify differences in telomere length in peripheral blood cells between patients with chronic schizophrenia (C-SCZ) and early schizophrenia (E-SCZ) and to identify any relationship between telomere length and disease chronicity and severity.
Relative average telomere lengths were determined using qPCR assay in patients with E-SCZ (n=42) and C-SCZ (n=44) hospitalized due to schizophrenia exacerbation. E-SCZ was diagnosed when less than 2 years had passed since the beginning of psychotic symptoms. The severity of symptoms was assessed using appropriate scales.
The severity of schizophrenia symptoms, as well as the number of psychotic episodes and hospital admissions, correlated significantly with telomere length in univariate analyses. Regression analysis revealed that a model incorporating study group (E-SCZ or C-ECZ), sex, and age, as well as the combined number of documented psychotic episodes and hospital admissions, can significantly predict the length of telomeres in patients with schizophrenia, with over 50% of variance in telomere length explained by the model (adjusted R (2)=0.512).
The results of the current study indicate that the recurrence of psychotic symptoms as well as their intensity and chronicity may be correlated with telomere attrition, which is well known to contribute to the development of premature senescence and age-related diseases.