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New Study Suggests Having a Pet Cat Increases the Risk of Schizophrenia

Could owning a cat double your risk of schizophrenia?

That’s the conclusion of a new review of 17 studies by researchers from the University of Queensland, Australia.

The team conducted a meta-analysis of existing research from 11 countries, including the US and UK, published over the last 44 years.

They found individuals exposed to cats before the age of 25 had approximately twice the odds of developing schizophrenia. 

In the paper, scientists pose that the link is likely due to a parasite found in pet cats called Toxoplasma gondii, also known as T. gondii, which can enter the body via a bite.

They say the parasite can enter the central nervous system and affect neurotransmitters in the brain, leading to personality changes, psychotic symptoms and psychiatric disorders such as schizophrenia. 

One US study included in the review, based on 354 students, found no association between cat ownership and scores on a schizotypy scale.

However, when comparing those bitten by a cat to those not bitten, the bitten subgroup had higher scores on a schizotypy scale.

A schizotypy scale is a questionnaire that measures traits of unusual and disorganized patterns of thinking – and is used to help diagnose schizophrenia.

Psychotic-like experiences may be delusions or hallucinations.

Figures suggest around one percent of the world population suffers from schizophrenia, with about two million in the US. 

It is a chronic and severe mental disorder that affects how a person thinks, feels, and behaves. 

People with schizophrenia may seem like they have lost touch with reality.

The cause of schizophrenia is not understood and it is believed to be a mix of genetics (hereditary), abnormalities in brain chemistry and/or possible viral infections and immune disorders. 

Symptoms of schizophrenia usually begin between ages 16 and 30. In rare cases, children have schizophrenia too.

The symptoms of schizophrenia fall into three categories: positive, negative, and cognitive.   

Positive symptoms are disturbances that are ‘added’ to the person’s personality and include hallucinations, delusions and thought disorders (unusual or dysfunctional ways of thinking). 

Negative symptoms are capabilities that are ‘lost’ from the person’s personality and include: ‘flat affect’ (reduced expression of emotions via facial expression or voice tone), reduced feelings of pleasure in everyday life and difficulty beginning and sustaining activities.

Cognitive symptoms are changes in memory or other aspects of thinking, including trouble focusing or paying attention, problems with ‘working memory’ and poor ability to understand information and use it to make decisions.

On Twitter, other researchers have criticized the review, saying it did not properly account for other potentially contributing factors – like social and economic background and family history.

For instance, one British study included found cat exposure during childhood, between the ages of four and 10 years, was associated with higher psychotic-like experiences at age 13 years.

But the findings did not persist after adjustment for potential confounding variables. 

Dr Sanil Rege, a psychiatrist based in Melbourne, tweeted: ’15/17 [studies included] are case-control studies notorious for spurious associations.’

Source : Daily Mail