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Researchers from the Centre for Genetic Origins of Health and Disease (GOHaD) at UWA and Curtin and the UWA Centre for Clinical Research in Neuropsychiatry (CCRN) have shown for the first time that the strength of genetic support for personality traits as endophenotypes for schizophrenia is broadly equivalent to that of cognitive traits.

Schizophrenia affects about 1% of the population, or around 150,000 to 200,000 Australians. Research has consistently shown that schizophrenia tends to cluster in families, with close relatives of a person with schizophrenia at a higher risk for schizophrenia than unrelated individuals.

To date, genome wide association studies (GWAS) have not been able to explain fully the genetic contribution to schizophrenia. This is partly due to the many individual differences in observable characteristics (phenotypes) of schizophrenia, and the large number of associated genetic polymorphisms, each with a small effect size.

Accumulating evidence has indicated that endophenotypes (unseen characteristics such as cognition and personality) might be causally related to the complex disease process of schizophrenia. Studying the genetic underpinnings of these endophenotypes may lead to new insights into the genes involved in schizophrenia and the underlying biological causes of the disease.

By using data from the Western Australian Family Study of Schizophrenia (WAFSS), GOHaD and CCRN researchers aimed to evaluate personality measures against defined endophenotype criteria and compare them to cognitive measures, which are more well-established endophenotype predictors for schizophrenia.

The current research examined twenty cognitive and personality measures, which were measured in 127 WAFSS families with at least one case of schizophrenia per family.

Results reported in Schizophrenia Bulletin show for the first time that personality traits could be promising endophenotypes for schizophrenia. When scored according to their candidacy as endophenotypes, rankings for the top personality traits are similar in magnitude to cognitive traits. Endophenotypes such as personality measures are not currently part of the clinical diagnosis of schizophrenia, but including both informative endophenotype information and a phenotypic diagnosis in genetic studies may help to provide novel insights into the causes of schizophrenia spectrum disorders.

One of the main weaknesses of this study is the narrow range of personality measures that were available to be examined, yet results were well powered and provide solid evidence for the first time that some personality measures, like cognitive performance, may provide insights into the underlying biology of schizophrenia.

The research suggests that a wider range of measures represent schizophrenia endophenotypes than previously thought, and presents the first comprehensive evidence for personality traits as endophenotypes of schizophrenia.

Media references

Dr Nina McCarthy , Centre for Genetic Origins of Health and Disease (GOHaD) and Centre for Clinical Research in Neuropsychiatry (CCRN)

Prof Assen Jablensky , Centre for Clinical Research in Neuropsychiatry (CCRN)