Both the skin and the brain develop from the same ectoderm and it is thought, therefore, that dermatoglyphics are informative for early disturbances in brain development in schizophrenia. This study was aimed at investigating the differences in both digital and palmar dermatoglyphic indices between twins discordant for schizophrenia and control twins. Furthermore, the significance of dermatoglyphic indices in relation to other determinants of brain development with regard to the susceptibility to schizophrenia was investigated. Data on dermatoglyphic indices of the hand and the palm were obtained from 21 same-sex discordant and 37 same-sex control twins. For 19 discordant and 25 control twins, there was also data available on brain volumes. Non-genetic intra-uterine circumstances early in pregnancy (10-13 weeks of gestation) are associated with a susceptibility to schizophrenia, since both the twins with schizophrenia and the unaffected co-twins showed more fluctuating asymmetry of the finger ridges (P <0.01), and marginally higher absolute finger ridge counts (P = 0.06) than control twin pairs. Fluctuating asymmetry of the finger ridges was as important as whole brain and left hippocampal volumes in differentiating twins with a high susceptibility to schizophrenia from those with a low susceptibility. © 2001 Elsevier Science B.V. All rights reserved.@en

Evidence is accumulating that developmental abnormalities, poor neuromotor function, and increased problem behavior precede the manifestation of schizophrenia itself. Information on school performance and behavioral development was obtained for 49 pairs of twins in which at least one twin suffered from schizophrenia (20 monozygotic [MZ], 29 dizygotic [DZ]) and for 43 pairs of healthy control twins (25 MZ, 18 DZ). Cox regression was used to analyze the contribution of schizophrenia, zygosity, sex, and year of birth to the age at which developmental divergence occurred. In both MZ and DZ twin pairs with schizophrenia, divergence in school performance occurred about 7.5 years earlier than it did in control twins, at 12 years of age, preceding the onset of psychosis by 10 years. This suggests that the first prodromal signs of schizophrenia manifest themselves as cognitive symptoms at the onset of puberty. Underperformance at school might therefore be considered one of the first signs of an until then latent vulnerability for schizophrenia.@en

Background: The study was designed to examine the relative contributions of genetic and nongenetic factors to structural brain abnormalities in schizophrenia and subjects at risk to develop the disorder. Methods: The brains of 15 monozygotic and 14 samesex dizygotic twins discordant for schizophrenia (patients) and 29 healthy twins pair-wise matched for zygosity, sex, age, and birth order were studied using high-resolution magnetic resonance imaging scans. Results: Intracranial and whole-brain corrected frontal lobe volumes were smaller (4.6% and 2.7%, respectively) in discordant monozygotic twins as compared with healthy monozygotic twins. Irrespective of zygosity, discordant twins had smaller whole-brain (2%), parahippocampal (9%), and hippocampal (8%) volumes than healthy twins. Moreover, patients had smaller whole-brain volumes (2.2%) than their nonschizophrenic cotwins, who in turn had smaller brains (1%) than healthy twins. Lateral and third-ventricle volumes were increased in discordant dizygotic twins as compared with healthy dizygotic twins (60.6% and 56.6%, respectively). Finally, within discordant twins, lateral ventricles were larger (14.4%) in patients than in their nonschizophrenic cotwins. Conclusions: Smaller intracranial volumes in the monozygotic patients and their cotwins suggest that increased genetic risk to develop schizophrenia is related to reduced brain growth early in life. The additional reduction in whole-brain volume found in the patients suggests that the manifestation of the disorder is related to (neurodegenerative) processes that are most likely nongenetic in origin.@en