Introduction: Genetic studies in schizophrenia have established that the risk of developing schizophrenia is increased if another family member is similarly affected, suggesting a strong hereditary component. The family studies also highlight that there is an increased psychiatric morbidity in the relatives of patients with schizophrenia. There are two reasons for reassessing genetic (more accurately, familial) transmission in schizophrenia from time to time: recent important changes in diagnostic criteria for this disorder and resultant sharp reductions in estimates of its prevalence; and methodological shortcomings of prior studies. With the use of family studies that include people of widely differing ages, it is useful to calculate the lifetime morbid risk-the likelihood that someone will suffer an episode of illness between birth and death-rather than the actual rate of development of the illness.
Aims: This study aims to assess the psychiatric morbidity among the first degree relatives (FDRs) of patients with schizophrenia and related disorders using family history method in an Indian sample
Methods: 126 cases were included from outpatient clinic and interviewed using SCAN (Schedule for Clinical Assessment in Neuropsychiatry) for diagnoses as per ICD-10. 113 had a diagnosis of schizophrenia and 13 had a diagnosis acute and transient psychotic disorder (ATPD). Key informants were interviewed using Family Interview for Genetic Studies (FIGS). 130 Controls were selected from the surgical outpatient clinic. Chi-square test, student's t test as appropriate was used. Odds ratio and 95% confidence interval to determine association between risk factors (i.e. positive family history for psychiatric disorders) and the outcome (disease status) were calculated. Morbidity risk for developing different disorders was calculated
Results: Data obtained about 113 case with schizophrenia and 13 with ATPD and their FDRs (798 FDRs of cases and 1050 FDRs of controls). The majority in both groups were aged 25–34 years. Mean duration of illness for cases was 5.010 years (SD = 4.872) before presentation to clinic. 24.6% cases with schizophrenia and acute psychosis had family history of psychiatric disorders in their FDRs, whereas 18.4% controls had such a history (p = 0.023). The commonest disorder among the FDRs of cases was schizophrenia. Other disorders are bipolar disorder, depression and substance abuse disorder. The siblings of schizophrenics are at a greater risk of developing schizophrenia as compared to the siblings of controls (OR = 4.4(95% CI = 1.226–16.190).
Conclusion: A spectrum of psychiatric disorders occur in FDRs ranging from non-affective to non-affective disorders and also neurotic disorders. This study adds to the available literature and data on the familial basis of schizophrenia and also replicates the finding shown earlier that among the first degree relatives, siblings are the most at-risk of developing the disorders.
