Early, non-psychotic deviant behavior in schizophrenia: a possible endophenotypic marker for genetic studies.

Early non-psychotic deviance occurs in some, but not all, pre-schizophrenic patients and has been linked to the later course of the disorder, suggesting its relationship with the schizophrenia syndrome. However, early deviance has rarely been explored as an endophenotypic marker in large samples of schizophrenic patients. We characterized the early childhood behavior and syndrome history of 205 adults with DSM-IV schizophrenia. Sixty percent of our sample had poor socialization, extreme fears/chronic sadness, and/or attention impairment/learning disabilities beginning before age 10. The remaining 40% were without behavioral difficulties until the onset of schizophrenia. Logistic regression analyses suggested that the risk of syndrome onset before age 17 was 2.5 times more likely among patients with poor socialization beginning before age 10. Schizoaffective disorder was 3.75 times greater among patients with extreme fears/chronic sadness in childhood, and schizophrenic patients with early attention impairment/learning disabilities were 2 times more likely to have a 1 degrees, 2 degrees or 3 degrees relative with schizophrenia. We concluded that early deviant behavior indicated a distinct subgroup of patients, and was linked to syndrome characteristics specifically relevant to genetic studies, in particular age at onset and family history of schizophrenia. Since early syndrome onset has been associated with specific genetic anomalies in other complex neuropathologic disorders, it may prove valuable to regard these early deviant behaviors as an indicator of early syndrome onset for future genetic studies of schizophrenia.