Global Study Links Cat Ownership to Happiness, But Parasite Poses Mood Risk
A 93-country investigation reveals a complex relationship between feline companions, national well-being, and the prevalence of Toxoplasma gondii.
A recent global study involving 93 nations has uncovered a surprising correlation between cat ownership and national happiness, suggesting that a higher density of cats may contribute to a more positive outlook. However, the research also highlights a significant caveat: the presence of the common parasite Toxoplasma gondii (T. gondii) in feline populations is linked to lower national happiness levels.
The study, which analyzed happiness metrics, cat density, GDP per capita, and health data, found that nations with more cats per capita generally report higher levels of self-reported happiness. The United States leads in cat population with 74.2 million, followed by China with 53.1 million. Happiness scores, averaged from 2022 to 2024, indicated a positive correlation between the number of felines and national joy.
Researchers initially aimed to explore the impact of economic factors like GDP and healthcare spending on national well-being, anticipating that exposure to T. gondii would negatively affect mood. The investigation sought to determine if cats themselves elevated spirits or if this effect was merely a byproduct of affluent pet owners.
Despite the positive association between cat density and happiness, the study observed a contradictory trend: regions with higher exposure rates to T. gondii, a parasite commonly found in cats, exhibit significantly lower happiness scores. This paradox appears to be influenced by socioeconomic factors and lifestyle. In wealthier societies, where cats are more likely to be kept indoors, fed commercial diets, and receive veterinary care, owners can benefit from companionship while minimizing parasite exposure. These pampered indoor cats have a reduced chance of becoming infected with T. gondii.
T. gondii is known for its ability to form cysts in muscle and brain tissues, and previous research has linked its infection to alterations in mood, cognition, and behavior, as well as potential links to neuropsychiatric conditions such as schizophrenia, OCD, anxiety, depression, and autism spectrum disorders. Scientists estimate that up to 30% of the global population may carry T. gondii without knowing it, and high infection rates can contribute to diminished national well-being.
Study co-author Dr. Indrikis Krams noted that while cats may indeed contribute to happiness, cat density could also serve as an indicator of broader social and economic conditions. "Our study cannot distinguish between these possibilities," he stated. The research suggests that the impact of cats on happiness is nuanced, with well-cared-for indoor cats offering benefits while outdoor or less-protected felines can introduce health risks that negatively affect mood.
![A scatter plot shows the positive correlation between cat density and national happiness, with data points and regression lines stratified by income level.]( "The correlation between cat density and national happiness was stratified by income level. Javier I. Borráz-León, et al., 2026)
Another co-author, Dr. Markus Rantala from the University of Turku, emphasized that the disparity in outcomes likely stems from differences in how cats are kept. "In wealthier countries, cats are more likely to live indoors, eat commercially prepared food, and receive veterinary care. These conditions reduce their chances of becoming infected," he explained.
Ultimately, the study indicates that the well-being benefits derived from cat ownership are closely tied to lifestyle and socioeconomic status, with pampered indoor cats contributing to happiness while parasite-carrying felines can have a detrimental effect on mood and overall national contentment. 
