La schizophrénie à début précoce : caractéristiques cliniques et endophénotypiques

Early onset schizophrenia is commonly considered as severe, resistant to treatment, and associated with a poor prognosis. It offers an interesting field of research for the neuro-developmental theory of schizophrenia, which hypothesises a link between some neuro-developmental markers such as physical and neurological anomalies, morphological brain abnormalities, and specific cognitive disturbances, with the existence of a vulnerability to a further occurrence of schizophrenic disorders. These markers, proved to be more common in schizophrenic patients, are considered by some authors as endophenotypes of schizophrenia. The objective of this study was to specify the clinical and endophenotypical features of early-onset schizophrenia. A comparative study was carried out on two groups of patients with schizophrenia according to DSM-IV criteria, who were systematically recruited from the outpatient clinic of psychiatry of the University Hospital of Monastir during the second semester of 2003. Patients who did not meet exclusion criteria (age over 50 years at study time, age of onset between 15 and 20, medical history of cranial trauma, evidence of cerebral disorders or mental retardation, addiction to alcohol or to psychoactive substances) were divided into 2 groups: Group I: onset before the age of 14 (N = 15). With a mean age at the time of the study of 20.8 ± 8.1 years and a gender distribution of 8 male vs 7 female patients; and Group II: onset after the age of 20 (N = 35), with a mean age at the time of the study of 34.6 ± 6.2 years and a predominance of male patients (80 %). The following tests were administered to both groups: Positive and Negative Syndrome Scale (PANSS), Evaluation of Global Functioning (EGF), Clinical Global Impressions (CGI), Minor Physical Anomalies Scale (MPAS) and Neurological Soft Signs (NSS). In the early-onset schizophrenia group, the disorganised subtype was predominant (60 %), in the second group the paranoid subtype was the most frequent (43 %) (P = 0.2). The severity of the disorder and of psychotic symptoms were more important in the early-onset schizophrenia group. Negative symptoms were predominant in group I (PANSS negative score = 30.6 ± 10.1 vs 24.9 ± 8.4 in group II) (P = 0.04). The physical and the neurological anomalies were more frequent in the early-onset group, with a total score of MPAS of 5.8 ± 2.8 vs 4.2 ± 2.4 (P = 0.04), and a score of NSS at 24.5 ± 6.1 vs 19.6 ± 5.4 (P = 0.006) respectively. These results show neurodevelopmental anomalies to be more common in early-onset schizophrenia, which could be interpreted as an association between early damages to the brain and occurrence of severe and early forms of schizophrenia. These findings highlight the probability of neurodevelopmental determinism in schizophrenia.