Which traits are related to schizophrenia?
Genes play a role in schizophrenia, the most common mental illness in Australia, but not all genes are created equal.
The study found that those with the most schizophrenia genes tended to be older and more male, had more co-morbidities, and were more likely to be black, poor, or in poorer health.
The same is true for those with a more complex history of psychiatric disorders, such as bipolar disorder or psychosis.
Some of these genetic variants are also linked to risk of developing schizophrenia.
Genes also affect other aspects of mental health and health outcomes.
“These genetic variants seem to influence a lot of things, including risk of having schizophrenia and psychotic disorders,” said lead author Dr Daniel Bressan, a professor of psychiatry and behavioural sciences at the University of Melbourne.
“If we want to get ahead of this pandemic we have to understand the genetic variants that predispose people to schizophrenia, so we can identify and intervene in those that we don’t understand.”
For the study, researchers looked at more than 13,000 people who were diagnosed with schizophrenia and matched them with a similar cohort of healthy people in Australia.
They also looked at a group of people with schizophrenia who had not been diagnosed.
They found that genetic variants associated with schizophrenia were linked to higher levels of co-occurring mental disorders and higher rates of mental illness.
For example, schizophrenia was linked to anxiety disorders, which are thought to be a result of a disruption of the neurotransmitter serotonin.
Other genes linked to schizophrenia include the gene for the hormone oxytocin, which is also involved in oxytocine release.
People with more cooccurring disorders were also more likely than people with fewer coexisting disorders to have schizophrenia.
The researchers found that schizophrenia was also linked with the gene FTO, which regulates the production of the stress hormone cortisol.
The other gene linked to the risk of schizophrenia was C-reactive protein, a marker for inflammation in the blood.
This inflammation can lead to heart disease and other conditions.
It was also the case that people with more schizophrenia were more frequently diagnosed with depression, anxiety, and depression-like symptoms, and less likely to have co-existing conditions.
The most common genetic variants linked to mental illness are rs761213 and rs1623.
These genes are also involved with a lot more psychiatric conditions.
For instance, rs1613 is linked to mood disorders and rs7613 is associated with psychosis.
These findings are important because they indicate that there may be genetic variants in the brain that increase the risk for mental health disorders, Bressam said.
“We don’t know if there are specific genetic variants, but the idea that there are genetic variants influencing mental health in people is a very intriguing hypothesis,” he said.
Dr Jodie Macdonald, a clinical psychologist and research associate at the National Health and Medical Research Council’s Centre for Mental Health and Addiction, said it was important to understand how genes interact with each other.
“What’s interesting about this study is that it looks at some genetic variants which might be associated with co-diagnoses of schizophrenia and that they’re related to co-risk factors for mental illness,” she said.
The research was published in the journal PLOS Genetics.
For more information on schizophrenia, including how to treat it, visit the Mental Health Foundation’s website.