Research: Owning cats could increase the risk of mental disorders in elderly people

A recent scientific analysis conducted by Australian researchers suggests that owning a cat as a pet may be associated with a higher risk of developing schizophrenia-related disorders. The study, led by psychiatrist John McGrath from the Queensland Centre for Mental Health Research, reviewed research carried out over the past 44 years across 11 countries.

The researchers emphasise, however, that the findings do not demonstrate that cats directly cause mental health problems. The study merely identifies a statistical association rather than a direct cause-and-effect relationship — an important distinction for cat owners to understand, including older adults who find companionship and emotional benefits in the presence of these animals.

According to the analysis, people exposed to cats had "approximately twice the likelihood of developing schizophrenia" after adjusting for several risk factors. The primary explanation under investigation centres on exposure to the parasite Toxoplasma gondii, which is commonly associated with cats.

The risks of the Toxoplasma gondii parasite

This parasite can be transmitted to humans through contact with the faeces of an infected cat, as well as through the consumption of undercooked meat or contaminated water. The US Centres for Disease Control and Prevention estimates that over 40 million people are infected with T. gondii, often without displaying any symptoms.

Once inside the body, the parasite can remain in the central nervous system and may influence neurotransmitters in the brain. In some earlier studies, it has been associated with personality changes, psychotic symptoms, and certain neurological disorders.

Contradictory results and the need for further research

The conclusions of the research are not, however, consistent. Some studies have found that exposure to cats during childhood may increase the risk of developing schizophrenia later in life, whilst other research has found no clear link. One study included in the analysis identified no significant association between owning a cat before the age of 13 and the subsequent onset of schizophrenia.

Specialists state that schizophrenia is a complex condition influenced by genetic, biological, and environmental factors. For older adults who own cats or are considering adopting a pet, it is important to know that the relationship between cats, T. gondii, and mental health requires considerably more research before any clear and definitive conclusions can be drawn.