Schizophrenia typically has its clinical onset in late adolescence to early adulthood. However, schizophrenia is a lifelong disorder, with numerous signs of abnormal development prior to its clinical onset.
Minor Physical Anomalies. Minor physical anomalies are structural deviations with little functional consequence that have been extensively studied because brain and skin are derived from the same ectodermal tissue. Thus minor physical anomalies are considered markers of early neurodevelopmental abnormalities (Lobato et al., 2001). Physical abnormalities are typical of neurodevelopmental disorders such as Down syndrome and epilepsy. Individuals with schizophrenia have a significantly greater number of anomalies than normal individuals. These include low-set ears, high arched palate, curved fifth finger, abnormal nail beds in the hands, excess branching of motor nerve endings, hypertelorism, small head circumference, and narrowing and elongation of the mid and lower facial region with widening of the skull base. The configuration of skin ridges (dermatoglyphics) has also been found to be abnormal or asymmetric in many patients with schizophrenia, including single simian crease and abnormal finger ridge counts. The pattern of minor physical and dermatoglyphic anomalies observed in patients with schizophrenia are indicative of prenatal insult around the second trimester of pregnancy, which may also affect the neuronal migration occurring at that time.
Functional Impairments. Generally, individuals who later go on to be diagnosed with schizophrenia suffer many functional impairments throughout their lives. Numerous studies using many different approaches have been used to try to identify premorbid precursors of schizophrenia. For example, researchers studied home movies of children who later went on to develop schizophrenia. Their motor and social behaviors were different enough from other children that following careful study, "blind" clinicians were able to identify the preschizophrenic children (Walker et al., 1994).
In some countries, large databases of neurocognitive and psychomotor performance are meticulously kept on children at various developmental time points. "Follow-back" studies of these databases revealed numerous socioemotional, cognitive, and motor abnormalities in children that were later diagnosed with schizophrenia. For instance, during infancy, many preschizophrenics were delayed in achieving milestones such as sitting up, standing, walking, talking, and continence (Isohanni et al., 2001). Throughout childhood, many have problems with speech, attention, sensory integration, and motor coordination, often being labeled clumsy. Preschizophrenic children are also more socially anxious and withdrawn and some studies reported a tendency to have poor scores on educational tests in school (Davies et al., 1998). Overall, these studies provide evidence that long before the clinical diagnosis of schizophrenia, these individuals have functional impairments.
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