Towards an Aetiological Classification of Schizophrenia

22q11 deletion syndrome: a genetic subtype of schizophrenia

“…Schizophrenia has usually been subtyped on the basis of symptom patterns (e.g., paranoid, disorganized, catatonic; or deficit syndrome) (Carpenter et al 1988) or familial (considered more genetic) and "sporadic" (considered relatively nongenetic or more environmental), based on family history of schizophrenia (Murray et al 1985). The principal rationale for subtyping is to reduce heterogeneity in the syndrome, and determine clinically meaningful divisions that have prognostic or etiologic significance.…”

“…Various attempts have been made to reduce heterogeneity in schizophrenia, primarily using clinical subtypes (Carpenter et al 1988) and sporadic/familial distinctions (Murray et al 1985). Recent evidence supports the likelihood that 22q11 Deletion Syndrome (22qDS) represents an identifiable genetic subtype of schizophrenia (Bassett et al 1998).…”

Schizophrenia is (not simply) a neurodevelopmental disorder

“…Attention has focused on those complications associated with a risk of hypoxic-ischaemic brain damage (Verdoux et al, 1997), as one of the possible causes for the ventricular enlargement observed in schizophrenic patients (Murray et al, 1985). Also, the reduced hippocampal size observed (Suddath et al, 1990) in schizophrenia has been related to the presence of OCs of the types associated with hypoxia-hyschaemia (Stefanis et al, 1999).…”

Gender differences in incipient psychosis

“…The neurobiological dimension could include four hypotheses regarding gender differences in schizophrenia: a) the estrogen hypothesis postulates a protective effect by estrogens in the development of schizophrenia in women which could explain certain gender differences in the manifestation of the disease 8 . In women, estrogens could retard schizophrenia development up to menopause, which would explain its late onset 9 ; b) different sub-types of schizophrenia: postulates the existence of two distinct schizophrenias, masculine and feminine 10 , corresponding to different forms of expression of specific psychotic symptoms according to the gender of the patient rather than the existence two types of schizophrenic endophenotypes which are clearly differentiated. Castle et al 11 , performed a study on a sample of patients with a first psychotic episode and identified three groups: a neurodevelopmental type (predominantly male), a schizoaffective type (almost entirely female) and a paranoid type (with equal sex ratio); c) early and late developmental models: both models postulate changes in the neurological development which predispose the appearance of schizophrenia, but in accordance with the early neurodevelopmental model, these anomalies start at the prenatal and neonatal stages 12 .…”