Offsprings of parents with severe mental disorders have an increased chance of developing the disorder. Patients and their families would benefit from knowing the exact risk that possibility. It was generally thought that familial risk is diagnosis specific. i.e. children are at risk of the same disorder as their parents. But newer evidence suggest that risk is much broader.
Daniel Rasic, Tomas Hajek, Martin Alda, and Rudolf Uher provide the most up-to-date quantification of familial risk in this meta analysis.They included all cross-sectional and longitudinal studies addressing the risk of SMI ( Severe Mental Illness: psychotic disorders/ mood disorders).They included only studies that systematically assessed offspring with a valid diagnostic interview at mean age of 10 years or higher. Offsprings had to be recruited through parents only.SMI in offspring was defined as schizophrenia or non affective psychosis, bipolar disorder (I or II) or major depressive disorder.
33 studies met criteria, giving information on 3863 offspring of parents with SMI. Mean age of off spring at last diagnostic assessment was 21.
1.The probability of offspring of parents with SMI developing SMI themselves was 0.32 (95% CI 0.24–0.42) .
2.Offspring of parents with SMI had a 2.5-fold increased risk of developing SMI compared with matched control offspring (RR = 2.52, 95% CI 2.08–3.06)
3. 55% of high-risk offspring suffered from any diagnosed mental disorder, with little differences by parental diagnoses.
4. There was evidence for partial specificity with largest RR for schizophrenia among offspring of parents with schizophrenia and largest RR for bipolar disorder among offspring of parents with bipolar disorder.
5. The risk of developing a psychotic or major mood disorder other than the disorder present in parent was increased 1.92 times (95% CI 1.48–2.49, P < .001) among offspring of parents with SMI. For comparison, the risk of the same disorder as diagnosed in the parent was increased by 3.59-fold.
There are only a small number of offsprings studies ( e.g.: in schizophrenia offsprings).Most studies made their diagnoses based on single cross-sectional assessment and not all disorders were assessed in most studies. Offspring had not been followed up through the age of peak risk of SMI onset in most studies. Results thus should be considered preliminary.
Conclusion: By early adulthood, the offspring of SMI has a 1-in-3 risk of developing a psychotic or major mood disorder and 1-in-2 risk of developing any mental disorder.There is partial specificity in schizophrenia and bipolar disorder.However , the familial risk extends across diagnostic boundaries.
Summary of the article:
Rasic D, Hajek T, Alda M, Uher R. Schizophr Bull. 2014 Jan;40(1):28-38