Association between PRODH gene rs372055 polymorphism and cognitive function in schizophrenia: findings from the digit span test

Background: Schizophrenia, a severe mental illness, is marked by disturbances in thought, cognitive impairments, negative symptoms, disorganized speech, hallucinations, catatonic behavior, psychotic symptoms, delusions, and behavioral changes. Schizophrenia has been associated with several gene polymorphisms and neurotransmitter imbalances. This study aims to analyze cognitive performance in schizophrenia patients using the Digit Span Test, with a focus on proline dehydrogenase (PRODH) gene polymorphisms. Material and Methods: This cross-sectional, observational analytic study included 99 individuals diagnosed with schizophrenia. Blood samples were collected and analyzed in the Biochemical Laboratory of the Medical Faculty of Andalas University using Polymerase Chain Reaction (PCR) to test for PRODH gene polymorphisms. The Structured Clinical Interview for DSM (SCID-1) was used to diagnose schizophrenia. Data were analyzed using the Chi-Square Test in SPSS 25.0, with statistical significance set at p = 0.05. Results: The cohort consisted of 99 patients who had been diagnosed with schizophrenia, most of whom were male (62.6%) with a median age of 37 years. A majority were unmarried (50.5%). PCR results revealed the following genotype distributions: homozygous dominant (CC) in 22 participants, heterozygous (TC) in 10, and homozygous recessive (TT) in 65. Cognitive function, as assessed by the Digit Span Test, yielded varied results in the forward span (p = 0.334) and higher deficit scores (score < 5) in the CT and TT groups than the CC group in the backward span (p = 0.314). However, these differences were not statistically significant. Conclusion: The PRODH gene polymorphism does not significantly affect cognitive function in patients with schizophrenia. Other factors may be more influential in shaping the cognitive function of individuals with schizophrenia.