IntroductionThe study of phenotypic extremes with an early-onset has been an important approach to the understanding of disease across all medical disciplines. 1 In different medical illnesses, the combination of greater severity, relative treatment resistance, greater heritability and earlier age of onset has been observed. 2 In Alzheimer's disease and breast cancer, important molecular genetic discoveries have been observed in subpopulations with an earlier age of illness onset. 3,4 Most cases of schizophrenia have their onset in late adolescence and early adulthood, but the disorder has been identified in children since early in the 20th century. 5 The nosological status of schizophrenia in children was controversial for many years, however the landmark studies by Kolvin and colleagues clearly differentiated schizophrenia with onset in childhood from autistic disorder. 6 Since 1990, a study of childhood-onset schizophrenia (onset of schizophrenia at the age of 12 or younger) has been ongoing at the National Institute of Mental Health (NIMH). 7 This study shows clear and consistent clinical and biological continuity between childhood-and adult-onset schizophrenia. To analyze clinical and demographic data of childhood-onset (12 years and younger) schizophrenia patients collected for a genetic study in schizophrenia, undertaken nationally in South Africa, using multiple parameters. Method: Patients with an onset of schizophrenia at 12 years or younger, were included. From the Diagnostic Interview for Genetic Studies (DIGS), patients' information and summary report data was tabulated and analyzed. Specific subgroups were further compared. This sub-population of 12 subjects was further compared with a group of the adult sample. Results: Of the 12 patients recruited, prominent results were: male to female ratio of 1:1; all had insidious onset of psychosis; a third had all 3 multidimensional impairment (MDI) symptoms; all patients that received ADHD treatment had ADHD treatment failure; two thirds had milestone delay; 58% had birth complications; a third were predominantly bottle fed; 42% had family history of schizophrenia; a third had family history of other major psychiatric conditions; all patients had at least one non-psychotic deviant behaviour (NPDB); no patient used cannabis; all delusions were paranoid; 92% had school achievement difficulty and a third had treatment resistance. Gender comparison included: earlier onset of psychosis in females; all females had aggression versus a third of males; more females had school achievement difficulty than males; males had more treatment resistance. Patients with MDI, compared to the sample average had: earlier onset of non-psychotic deviant behaviour; lower school drop-out rate; less social difficulty and no treatment resistance.
Conclusion:The results compare well to previous research on this topic. The new concepts introduced by the present study require further investigation.