Color Perception in Patients with Schizophreniza and Their Healthy First-degree Relatives: A Cross-sectional Study

Background: Endophenotypic markers are an important area of study for a better understanding of the biological basis of disorders such as schizophrenia. Our study evaluated color vision as a potential endophenotypic marker in schizophrenia. Methods: This was a cross-sectional study at a tertiary care center with 39 patients diagnosed with schizophrenia and 39 healthy first-degree relatives (FDRs). After screening for ocular disorders and color blindness, all participants underwent the Farnsworth–Munsell D-100 test for color perception, the Montreal Cognitive Assessment (MoCA), and a symptom severity assessment with the Positive and Negative Syndrome Scale. Statistical analyses included t tests, correlations, and regression models. Results: All patients demonstrated poor color discrimination (total error score [TES] > 100), compared with 66.7% of FDRs. The mean TES of patients was 225.5 ± 64.3, and that of FDRs was 143.7 ± 50.9, both indicating impaired color discrimination. This deficit was not specific to any one color axis. Patients had significantly lower MoCA scores (20.5 ± 5.1) compared to FDRs (25 ± 2.7) ( p < .001). Color perception deficits correlated positively with negative symptom scores ( ρ = 0.39, p = .04) and negatively with MoCA scores ( ρ = −0.44, p = .005). Regression analysis indicated that cognitive function was the strongest predictor of color perception impairment. Among FDRs, TES correlated significantly with age and MoCA scores. Conclusions: Patients with schizophrenia exhibited marked impairments in color discrimination, and this was shared with FDRs. This suggests that impaired color vision may represent a potential endophenotypic marker of schizophrenia, warranting further longitudinal research.