1. Key research: Gottesman et al
Key research: Gottesman et al. (2010) Severe mental disorders in offspring with two psychiatrically ill parents

2. Background
Previous research has found that if one parent has a mental disorder there is a increased likelihood of the child also having a mental disorder. This study wanted to investigate if two parents had a mental disorder would even further the risk of their child also having a disorder.
The aim of the study was to investigate whether two parents with mental disorders would increase the probability that their child would also be diagnosed with a mental disorder.
Aim
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3. Participants
Records from the population of Denmark were gathered using the Civil Registration System.
No consent was needed as the data gathered was from public domain and names were anonymous.
1,278,977 couples were studied, with some having more than one child.
These couples were split into four groups: Diagnoses were taken from discharges from hospitals that used the ICD-8 and ICD-10.
Group A – 2 parents with a diagnosis of either schizophrenia, depression or bipolar disorder.
Group B – 1 parent with a diagnosis of either schizophrenia, depression or bipolar disorder.
Group C – Neither parent diagnosed with a disorder.
Group D – A group of ‘general public’ where there was no data provided about psychiatric illnesses.
The children of each couple had any mental diagnoses checked on the national register.
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4. Guess which % goes in which column
Group A
Both parents
Group B
One parent
Group C
Neither parent
Group D
General pop.
Group E
Both bi.p
Group F
One S. one Bi.p 7%
1.12%
39.2%
15.6%
4.8%
0.86%

5. Group A
Both parents
Group B
One parent
Group C
Neither parent
Group D
General pop.
Group E
Both bi.p
Group F
One S. one Bi.p
39.2% 7%
0.86%
1.12%
4.8%
15.6%

6. Results – Schizophrenia
27.3% of offspring were diagnosed with schizophrenia when both parents were diagnosed with schizophrenia.
15.6% of offspring were diagnosed with schizophrenia when one parent was diagnosed with schizophrenia and the other was diagnosed with bipolar disorder.
7% of offspring were diagnosed with schizophrenia when one parent was diagnosed with schizophrenia only.
4.8% of offspring were diagnosed with schizophrenia when both parents were diagnosed with bipolar disorder.
1.12% of offspring were diagnosed with schizophrenia from a sample of the general population.
0.86% of offspring were diagnosed with schizophrenia when neither parents were diagnosed with schizophrenia.
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7. In summary
Offspring are 31.7 times more likely to have schizophrenia when both parents have schizophrenia.
Even when just one parent has schizophrenia the offspring is still 3.9 times more likely to also be diagnosed.
And even if parents are diagnosed with another disorder like bipolar disorder, the offspring is 2 times more likely to be diagnosed with schizophrenia.
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9. Guess the % for bipolar disorder
Group A
Both parents
Group B
One parent
Group C
Neither parent
Group D
General pop.
Group E
Both s.
Group F
One S. one Bi.p
4.4%
0.48%
36%
10.8%
0.63%
11.7%

10. Guess the % for bipolar disorder
Group A
Both parents
Group B
One parent
Group C
Neither parent
Group D
General pop.
Group E
Both s.
Group F
One S. one Bi.p
36%
4.4%
0.48%
0.63%
10.8%
11.7%

11. Results – Bipolar Disorder
24.9% of offspring were diagnosed with bipolar disorder when both parents were diagnosed with bipolar disorder.
10.8% of offspring were diagnosed with bipolar disorder when both parents were diagnosed with schizophrenia.
4.8% of offspring were diagnosed with bipolar disorder when one parent was diagnosed with bipolar disorder and the other was diagnosed with schizophrenia.
4.4% of offspring were diagnosed with bipolar disorder when one parent was diagnosed with bipolar disorder only.
0.63% of offspring were diagnosed with bipolar disorder from a sample of the general population.
0.48% of offspring were diagnosed with bipolar disorder when neither parents were diagnosed with bipolar disorder.
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12. In summary
Offspring are 51.9 times more likely to have bipolar disorder when both parents have bipolar disorder.
Offspring are 2–3 times more likely to have bipolar disorder when they have just one parent with the same disorder.
When both parents are diagnosed with schizophrenia they are 10 times more likely to be diagnosed with bipolar disorder.
Older offspring (45 years of age) are not diagnosed as with schizophrenia, which suggests that age has an effect on whether a person is diagnosed.
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13. Conclusion
Gottesman’s study supported the findings of other studies finding that there is a link between parents and offspring in diagnoses of mental illness. The excellent sample size of this study further confirms this idea.
This study could be useful for people who make decisions about marriage, children and future planning.
In addition, the study also claims that the ICD is a valid measure of mental illness.

14. Evaluation questions
Describe the sample study and explain how the study can be generalised. [3]
Name three types of methodology that was used to build up a case study for each individual and explain how this contributes to reliability. [3]
How is this research social sensitive (3)?
What future studies could be done?