Relax, your cat won’t make you mentally ill

    23 February 2017

    Is having a cat bad for your mental health? It’s not as ridiculous a question as it might sound. For some time it has been speculated that cat ownership may pose a greater risk of mental health problems. That’s because of the common parasite Toxoplasma gondii, which can only reproduce in cats’ stomachs.

    Earlier research has suggested that humans infected with the parasite are up to seven times more likely to commit suicide, and are more prone to psychiatric disorders such as schizophrenia and obsessive compulsive disorder.

    A new study, carried out by researchers at University College London, found no evidence of a link between the parasite and depression.

    Researchers looked at the mental health of 5,000 people until the age of 18. It was found that, after adjusting for other factors, children who grow up around cats are no more likely to develop mental health problems in adolescence.

    There was no clinical analysis to establish how many of those children were infected with the parasite, which is believed to infect about 40 per cent of people at some point in their lives, regardless of whether they own a cat.

    There is, however, a risk of physical health problems for pregnant mothers who are exposed to the parasite. It can cause miscarriage or physical deformities in the child.

    Dr Francesca Solmi, the study’s lead author, said: ‘The message for cat owners is clear — there is no evidence that cats pose a risk to children’s mental health.

    ‘In our study, initial unadjusted analyses suggested a small link between cat ownership and psychotic symptoms at age 13, but this turned out to be due to other factors.

    ‘Once we controlled for factors such as household over-crowding and socioeconomic status, the data showed that cats were not to blame.

    ‘Previous studies reporting links between cat ownership and psychosis simply failed to adequately control for other possible explanations.’

    Instant analysis
    It is important to be clear that this study relates specifically to mental health problems in teenagers growing up in households with cats, not long-term cat ownership in adults. Adolescent and adult mental health is a hugely complex issue and, as such, it is very challenging to make any specific claims around causation. That is part of the criticism of previous studies in this area.

    This was a large study and claims to have adjusted for other factors. But it cannot really tell us about the link between toxoplasmosis itself and mental health problems, as it is not possible to say whether any of the participants actually contracted it. Longer-term data would be helpful in strengthening the claims made by the research.
    Research score: 3/5