Pre and perinatal complications

More than 20 studies have shown that patients suffering from schizophrenia are more likely to have a history of pre- or perinatal complications (collectively termed obstetric complications) than are healthy subjects from the general population, patients with other psychiatric disorders, and their own healthy siblings. (23) Some of the studies which reported these findings were based upon interviews with patients' mothers asking them to recall their pregnancies; such interviews are obviously open to distortion by loss of, or faulty, memory. However, similar findings have been reported by studies examining data collected in obstetric records at the time of birth of patients and controls/24 A further assessment of the epidemiological studies of obstetric complications as risk factors for schizophrenia is given in Ch§pter 4.3..4.

Of course, it is possible that the excess obstetric complications in schizophrenia may be the consequence of some pre-existing abnormality. Since the fetus plays an active role in the normal progress of pregnancy and labour, fetal impairment induced by earlier abnormality may itself result in some perinatal complications. Also some studies have shown that women with schizophrenia who become pregnant tend to have more obstetric complications, possibly owing to their behaviour during pregnancy, for example smoking and not attending antenatal visits.

The term of 'obstetric complications' covers a broad range of obstetric events. A recent international collaboration therefore gathered data on more than 700 schizophrenics and a similar number of controls to see whether the general association could be explained by one or two specific complications; low birth weight, prematurity, and resuscitation at birth were particularly increased in the schizophrenics; (23 other complications that have been implicated include retarded fetal growth and rhesus incompatability. Thus, a common characteristic of most of the obstetric complications implicated is that they increase the risk of hypoxia.

Could hypoxic-ischaemic damage be the mechanism that increases the risk of later schizophrenia? Children who were subject to cerebral hypoxia at or before birth show an excess of abnormalities on MRI scan, of minor neurological signs, and of cognitive and behavioural problems, characteristics also found in many preschizophrenic children.(25) As one might predict, studies of monozygotic twins discordant for schizophrenia have shown that the affected twins have larger lateral ventricles and smaller hippocampi than their well co-twins; k6,27) furthermore, those twins who have been subjected to the most severe perinatal difficulties have the largest ventricles and smallest hippocampi/28

Similarly, Stefanis et al.(29) compared hippocampal volume in schizophrenics with other affected relatives but no history of obstetric complications, schizophrenics with no affected relatives but a history of significant obstetric complications, and normal controls. Hippocampal volume was normal in the first schizophrenic group but reduced in the second group, implying that it is hypoxic-ischaemic damage rather than genetic predisposition alone that determines decreased hippocampal volume in schizophrenia.

Many studies have shown that more schizophrenic persons are born in late winter and spring than expected; since respiratory viral infections such as influenza tend to occur in autumn and winter, maternal infection might provide the explanation. A number of epidemiological studies have, therefore, addressed the question of whether maternal exposure to influenza during the second trimester of pregnancy is a risk factor for schizophrenia; some but not all studies have suggested that it is.(30) Recently, one study has raised the possibility that prenatal exposure to rubella may have a similar risk-increasing effect for schizophrenia while another implicated maternal malnutrition;(31) neither of these reports has yet been replicated. See also Chapter.4.3.,4. for a more cautious assessment of the strength of the evidence that maternal exposure to influenza is a risk factor for schizophrenia.

Funny Wiring Autism

Funny Wiring Autism

Autism is a developmental disorder that manifests itself in early childhood and affects the functioning of the brain, primarily in the areas of social interaction and communication. Children with autism look like other children but do not play or behave like other children. They must struggle daily to cope and connect with the world around them.

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