Fingerprint Ridge Density in Schizophrenia: A Comparative Study in Kano State, Nigeria

Schizophrenia is a complex neurodevelopmental disorder influenced by genetic and prenatal environmental factors. Dermatoglyphic traits, particularly fingerprint ridge density (RD), are established during early foetal development and may serve as non-invasive markers of developmental disturbances associated with schizophrenia. This study investigated fingerprint ridge density patterns among individuals with schizophrenia and controls in Kano State, Nigeria, and examined sex-related differences. A comparative cross-sectional study was conducted among 109 schizophrenia patients and 111 controls aged 18–60 years. Ridge density was assessed in the ulnar (URD), radial (RRD), and proximal (PRD) regions of all ten digits using a standardized 5 mm × 5 mm counting technique. Females demonstrated consistently higher ridge density values than males across both groups, confirming sexual dimorphism. Compared with controls, schizophrenia patients exhibited significantly lower ridge density values across multiple digits and regions. The reductions were more pronounced among males, particularly in the thumb, ring, and little fingers, and were associated with moderate-to-large effect sizes. Female patients also showed significantly lower ridge density values, especially in the index, middle, ring, and little fingers, although the differences were generally less marked than those observed among males. Bilateral reductions were predominantly evident within the ulnar and radial regions, suggesting altered prenatal epidermal ridge development. These findings provide further support for the neurodevelopmental hypothesis of schizophrenia and indicate that fingerprint ridge density may represent a simple, inexpensive, and non-invasive biomarker of developmental instability associated with the disorder.

Key Words: schizophrenia, fingerprint, ridge density, dermatoglyphics, sexual dimorphism, Nigeria