Intellectual functioning in schizophrenia has been associated with genetic vulnerability and obstetric complications.
The aim of this study was to assess:
– the incidence of complications during pregnancy, labor and delivery;
– the association of OCs with general intellectual ability in two groups: patients with schizophrenia and their healthy siblings.
Forty-two patients with schizophrenia according to DSM-IV and 43 their healthy siblings were included in the study and examined using MINI and WAIS-R. Their mothers were interviewed to gather data on OCs. The ‘midwife protocol’ of Parnas et al. was used to quantify the presence and entity of OCs.
Asphyxia, mother's serious illness during pregnancy, premature delivery with weight < 2500 g, labor time > 48 h, infarcts in the placenta and eclampsia were statistically more frequent in schizophrenic group. OCs were more common in individuals with a family history. The two investigated groups were different in the following WAIS-R subtests: comprehension (P = 0.018), block design (P = 0.0001), digit symbol (P = 0.001), as well as in performance IQ and total IQ. In the patient group, correlations between OCs indexes and WAIS-R results include all intelligence quotients (verbal, performance, total IQ) and 5 WAIS-R subtests, while in the sibling group: verbal and total IQ and 2 subtests. The correlation between Vocabulary subtest and OCs was the strongest in both groups.
OCs may interact with genetic vulnerability to increase the risk of schizophrenia and have been associated with cognitive deficits in the patient group.
The authors have not supplied their declaration of competing interest.