Schizophrenia and Its Association with Biological and Environmental Factors: A Community Based Study

Aims: The aim of this study was to examine the proportion of probable schizophrenia in Arab population visiting primary health care centers and investigate its associated biologic and environmental factors.
Study Design: Cross sectional study.
Place and Duration of Study: Primary Health Care (PHC) centres, Supreme Council of Health, Qatar, between January 2009 to December 2010.
Subjects: Of 1491 Arab patients approached, 1148 patients agreed to participate in the study (77%).
Methods: The study was based on a face to face interview with a designed questionnaire including socio-demographic, biologic and environmental factors. A diagnostic screening questionnaire which consisted of 6 questions about the symptoms of schizophrenic disorders was used for the diagnosis of schizophrenia.
Results: Of the studied subjects, 11.7% of them were diagnosed with schizophrenia. A significant association was observed between schizophrenic and non-schizophrenic patients in terms of age group (p=0.048), BMI (p=0.019), gender (p=0.027), ethnicity (p=0.008), marital status (p=0.001), occupation (p<0.001), household income (p<0.001) and place of residence (p=0.039). Obstetric complications were significantly higher in schizophrenic patients with a higher frequency of pregnancy stress (31.3%; p<0.001) and diabetes (20.1%; p=0.008). Among the obstetric complications, Rhesus incompatibility (OR 2.74; 95% CI (1.16-6.47); P=0.021) and pregnancy stress (OR 2.51; 95% CI (1.60-3.94); P<0.001) were the major predictors for the development of schizophrenia. Delivery complications of asphyxia (17.9%; p=0.003), uterine atony (10.4%; p=0.028) and emergency caesarean section (17.2%; p=0.024) were significantly higher in mothers of the patients. Urban upbringing (OR 1.60; 95% CI (1.02 - 2.50); P<0.037) and social isolation (OR 1.72; 95% CI (1.06-2.74); P<0.027) were the main significant environmental risk factors for schizophrenia.
Conclusion: An increasing schizophrenia risk with obstetric complications was observed in the study sample. Rhesus incompatibility and pregnancy stress were the main predictors for schizophrenia.