Objective: There is an important relationship between chronic schizophrenia and cognitive capacity. There are several researches studying the relation between cognitive and metabolic parameters after antipsychotic use in literature; however there exists no study in first episode schizophrenia patients not using drugs. Early and proper treatment is very important for the prognosis of first episode schizophrenia patients.
Methods: 27 patients with the diagnosis of schizophrenia according to DSM-IV-TR were included into the study. Patients were recruited either from outpatient clinics or from inpatient wards between 2009 and 2013. Serum lipid profile (total cholesterol, HDL, LDL, VLDL cholesterol), free T3, free T4, thyroid stimulating hormone (TSH), and serum fasting glucose levels were obtained in all patients. All patients underwent neuropsychological tests (Wisconsin Cart Sorting Test, Stroop Test, Rey Auditory Learning Verbal Test, Trail Making Test, Continuous Performance test, Serial Digit Learning Test, and N-back Test). The cognitive findings were evaluated in 3 fields: learning and memory, executive functions, and attention. Spearman’s correlation analysis was performed to explore the relationship between serum lipid, thyroid profile, fasting glucose levels and learning-memory, attention, and executive functions.
Results: Demographic characteristics: Mean age (± standard deviation) was 23.9±6 years; 56% of patients are men; the mean education in years was 9.6±2.8. Learning and Memory: There was an inverse and significant correlation between Rey Visual Design Learning Test and free T4 levels (r=-0.200; p=0.05). An inverse correlation was observed between Rey Visual Memory Test and free T4 levels as well; however it has not reached the significant level (r=-0.431; p=0.1). Executive functions: Among executive functions, Wisconsin Card Sorting test and serum fasting glucose levels correlated inversely with no statistical significance (r=-0.464; p=0.053).
Attention: There was an inverse and significant correlation between CPT (2 day) scores and triglyceride levels (r=0.766; p=0.010). CPT percentage score and TSH level correlated positively but this association was not significant (r=0.643; p=0.086); on the other hand, it showed an inverse and significant correlation with serum VLDL levels (r=-0.737; p=0.037).
Conclusion: Serum lipid profile, glucose level, and thyroid function tests appear to have an impact on first episode schizophrenia patients. This research is the first study in literature exploring the association between blood lipid levels, glucose level, thyroid function and cognitive function on first episode schizophrenia patients. Yet more studies with larger sample size are needed for a definite conclusion.