Schizophrenia in people with intellectual disability: the role of pregnancy and birth complications

Abstract

The literature suggests that mental illness is more common in people with intellectual disability than in the general population. Having reviewed the literature, Turner (1989) [Psychological Medicine 19, 301-14] suggested that about 3% of people with intellectual disability also have schizophrenia. As pregnancy and birth complications (PBCs) occur more commonly in people with intellectual disability than in the general population and are also implicated in the aetiology of schizophrenia, it is possible that these conditions share a common aetiology. This study reports on the occurrence of PBCs in those people with intellectual disability who develop schizophrenia. Fifty people with intellectual disability and schizophrenia were matched for age, sex, degree of intellectual disability and presence of epilepsy with a control group who did not suffer from schizophrenia or a schizophreniform psychosis. The obstetric history was obtained and events rated on a scale specifically designed for this study. This PBCs scale consists of six sub-scales covering areas of general maternal health, pregnancy, delivery, medication in labour, total medication score and neonatal score, as well as an overall total score. The study found that people with intellectual disability who develop schizophrenia have significantly higher rates of PBCs than controls. All of the sub-scales on the PBCs scale were significantly higher in people with schizophrenia, with the exception of the medication scales. Only five out of the 50 people with schizophrenia had not had a major obstetric complication, compared to 13 subjects from the control group. A number of abnormalities were specifically higher in people who later developed schizophrenia. These included: abnormally long or short labour; maternal episiotomy; maternal preeclamptic toxaemia; induction of labour; dysmaturity; maternal smoking in pregnancy; and a delay in neonatal crying. The results suggest that PBCs are important in the aetiology of schizophrenia in people with intellectual disability.

Genetics, Perinatal Insult and Schizophrenia: The Mechanism Underlying an Increased Prevalence of Perinatal Complications Among Individuals with a Diagnosis of Schizophrenia?

“…Different brain areas, and different stages of fetal maturation might affect the impact of a braindamaging event, which may lead to very different behavioral consequences: cognitive abnormalities, mood alterations, mental retardation, or proneness to violence. In some groups of patients diagnosed with schizophrenia, indeed, some overlap of mood instability, antisocial behaviors, and cognitive impairment was described, with some relationship with obstetric complications [70,146,147].…”

Beyond the first episode: Candidate factors for a risk prediction model of schizophrenia

“…It is also known that individuals with generalized intellectual disability are at higher risk of schizophrenia and other psychotic disorders than the general population (Bouras et al, 2004;Nettelbladt, Gö th, Bogren, & Mattisson, 2009) with pregnancy and birth complications likely to be relevant (O'Dwyer, 1997).…”

Discrete Placental Dysfunction: The Overlooked Player in Prenatal Roots of Neuropsychiatric Diseases?

“…Furthermore, an interesting interrelation between preeclampsia and schizophrenia has been reported [26,27]. On this basis, one might hypothesize that other placental disorders with less severe maternal clinical symptoms and more discrete disturbances of placental maturation, such as terminal villous deficiency, hypermaturity, and retardation of placental maturation [31], may also play a role in the etiopathogenesis of schizophrenia and other neuropsychiatric diseases.…”

“…24,25]. Fifth, an association has been shown between preeclampsia during the third trimenon of pregnancy and an increased incidence of schizophrenia [26,27].…”

“…However, uniform mechanisms could not be shown so far. It may therefore be an attractive approach to consider preeclampsia -being a risk factor for schizophrenia [26,27] and primarily a placental disease [28][29][30][31][32] -as a starting point for further research testing whether discrete placental dysfunction in general is an important contributive factor in the etiopathogenesis of neuropsychiatric diseases.…”