- Owning a cat is linked to a doubling of the risk of developing schizophrenia
- However, other researchers have called for better quality studies
- READ MORE: Marijuana may be responsible for 30% of schizophrenia cases in men
Can owning a cat double your risk of schizophrenia?
That is the conclusion of a new review of 17 studies by researchers at the University of Queensland, Australia.
The team conducted a meta-analysis of existing research from 11 countries, including the US and Britain, published over the past 44 years.
They found that individuals exposed to cats before the age of 25 were about twice as likely to develop schizophrenia.
In the article, scientists say the link is likely due to a parasite found in domestic cats called Toxoplasma gondii, also known as T. gondii, which can enter the body through a bite.
They say the parasite can invade the central nervous system and affect neurotransmitters in the brain, leading to personality changes, psychotic symptoms and psychiatric disorders such as schizophrenia.
Researchers from the University of Queensland, Australia, found that individuals exposed to cats were about twice as likely to develop schizophrenia compared to those who had never owned a cat.
An American study included in the review, based on 354 students, found no link between cat ownership and scores on a schizotypy scale.
However, when those who had been bitten by a cat were compared with those who had not been bitten, the bitten subgroup had higher scores on a schizotypy scale.
A schizotypy scale is a questionnaire that measures characteristics of unusual and disorganized thought patterns – and is used to help diagnose schizophrenia.
Psychotic-like experiences can be delusions or hallucinations.
Figures show that approximately one percent of the world's population suffers from schizophrenia, of which approximately two million in the US.
It is a chronic and serious mental disorder that affects how a person thinks, feels and behaves.
It may seem as if people with schizophrenia have lost touch with reality.
The cause of schizophrenia is not understood and is believed to be a combination of genetics (hereditary), abnormalities in brain chemistry, and/or possible viral infections and immune disorders.
Symptoms of schizophrenia usually begin between the ages of 16 and 30. In rare cases, children also have schizophrenia.
The symptoms of schizophrenia fall into three categories: positive, negative, and cognitive.
Positive symptoms are disorders that are 'added' to the person's personality and include hallusions, devasions and tHought disorders (unusual or dysfunctional ways of thinking).
Negative symptoms are abilities that are 'lost' in the person's personality and include: 'flat affect' (reduced expression of emotions through facial expression or vocal tone), rdeveloped feelings of pleasure in everyday life and difficulty starting and continuing activities.
Cognitive symptoms are changes in memory or other aspects of thinking, including problems concentrating or paying attention, problems with 'working memory' and a poor ability to understand information and use it to make decisions.
On Twitter, other researchers criticized the review, saying it did not properly take into account other factors that could potentially contribute, such as social and economic background and family history.
For example, a British study found that exposure to cats during childhood, between the ages of four and ten, was associated with higher psychotic-like experiences at the age of 13.
But the findings did not hold after adjusting for potential confounding variables.
Dr. Sanil Rege, a psychiatrist based in Melbourne, tweeted: “15/17 [studies included] are case-control studies that are notorious for their spurious associations.”