A parasite found in cats is tampering with people’s brains and driving them to suicide, research suggests.
Scientists have shown that men and women infected with a bug that breeds in cats’ stomachs and worms into people’s brains are seven times more likely to attempt suicide than others.
They say that Toxoplasma gondii may tinker with the delicate chemistry of the brain and screening people for it could help identify those at risk of taking their own lives.
The parasite, which is carried by many Britons, has a complicated life cycle but can only breed inside cats. The microscopic eggs are passed on in cat faeces, spreading the infection.
Pregnant women are advised not to empty cat litter trays because the parasite can be fatal to unborn babies. The bug can also be picked up from contaminated food.
Around a third of people worldwide carry the parasite, with most catching it by consuming undercooked meat, especially lamb, pork and venison or by ingesting water, soil or anything contaminated by cat faeces.
Scientists looked for evidence of the infection in the blood of 84 men and women, more than half of whom had tried to commit suicide.
Dr Lena Brundin, of Michigan State University, said: ‘We found that if you are positive for the parasite, you are seven times more likely to commit suicide.’
She said that the parasite, which has previously been linked to brain cancer, schizophrenia and personality disorders, may inflame the brain or tamper with its chemistry, including levels of the ‘feel-good’ chemical dopamine.
Those behind the latest study stressed that not everyone who is infected will be suicidal. However, they said if the link is confirmed, screening for the bug could make it easier to determine which mental health patients are at the greatest risk of attempting suicide.
Knowing more about the biology that precedes suicide could also lead to the creation of better anti-depressants.
Dr Brundin said: ‘It means we can develop new treatments to prevent suicides and patients can feel hope that maybe we can help them.’