Cat Ownership at Ages 4-5 Linked to Worse Mental Health Measures in Children at Ages 7-8

Owning a cat during early childhood — specifically at ages 4 to 5 — was associated with an increased risk of both internalizing and externalizing mental health problems by ages 7 to 8, according to a study published in the World Journal of Pediatrics. The finding, drawn from a Spanish birth cohort of nearly 1,900 mother-child pairs, stands out against a backdrop of largely inconclusive prior research on whether pet companionship benefits children's psychological development.

The research emerged from the Infancia y Medio Ambiente (INMA; Environment and Childhood) project, launched in the early 2000s across seven areas of Spain. The cohort was initially established to examine how environmental factors such as pollutants affect child development, and was later expanded to capture pet ownership. Investigators drew on medical records, parental sociodemographic data, and questionnaires administered at pregnancy, birth, age 1, ages 4-5, and ages 7-8.

Behavioral Screening at Ages 7-8

Parents completed a behavior screening questionnaire when their children reached 7-8 years old, covering emotional symptoms, conduct problems, hyperactivity, peer problems, and prosocial behavior. The researchers categorized outcomes into internalizing behaviors — inwardly directed stress responses that may include inner turmoil associated with depression (搜索)搜索该疾病 or anxiety (搜索)搜索该疾病 — and externalizing behaviors, which are outwardly directed and may break rules or social norms and cause turmoil in others.

About one-quarter of the 1,893 families had always owned a pet, most commonly a dog or cat. The analysis found that cat ownership at ages 4-5, but not at age 1, was associated with an increased risk of both problem categories. By contrast, owning "other" animals — not a dog, cat, or bird — during both early childhood follow-ups appeared protective, associated with a reduced risk of internalizing and externalizing problems. These less common pets included rabbits, hamsters, fish, turtles, and salamanders.

Dog and bird ownership showed no significant associations with children's mental health in either direction, and the remaining pet companionship scenarios likewise produced no significant findings.

Competing Explanations for the Cat Signal

The authors offered several hypotheses for why cats diverged from other pets. One attachment model suggests emotional bonds may not be fully formed until age 18, meaning benefits could emerge later. Alternatively, "little" pets such as rodents, fish, and reptiles may inspire weaker emotional bonds because they are more evolutionarily distant from humans — yet these were the only animals linked to mental health improvement, perhaps because they are often regarded as "children's pets" that are easier to care for.

Interaction patterns may also matter. Cats do not typically engage owners in mental-health-boosting outdoor activities like jogging and fetching, and generally stay indoors. The researchers also noted that cats can be "less affectionate, exhibit avoidant attachment, and are often chosen by families with children who have mental health conditions, due to their lower maintenance needs."

That last point bears directly on interpretation: because the study is observational, it cannot untangle whether cats contribute to behavioral problems or whether families with affected children are more likely to choose them. The problems could have existed before a cat entered the household. The authors also raised the possibility that feline-associated effects may be influenced by toxoplasmosis (搜索)搜索该疾病, which affects about one-third of the global population and can adversely impact cognition and mental health in children.

Attachment Theory and the Limits of the Evidence

The study's framing rests on the premise that attachment — the formation of emotional bonds — is crucial for social development and need not involve a caregiver alone. A childhood pet can ostensibly yield socio-cognitive benefits, including increased compassion toward animals and strengthening a child's responsibility and moral norms, while helping children understand nonverbal language and improve prosocial behaviors. Children can also reduce stress by feeling supported and loved by a family pet and build confidence through caretaking.

The researchers acknowledged that effects may simply not be apparent yet at ages 7-8, since psychological traits that pets may influence continue developing into adolescence. They concluded that the data "highlights the complex relationship between early pet ownership and child mental health."

The findings are not uniform across the literature. A small 2021 study found that after cat adoption, children with autism (搜索)搜索该疾病 showed greater empathy, less separation anxiety (搜索)搜索该疾病, and fewer externalizing, hyperactivity, and inattention behaviors — a more favorable picture than the INMA results suggest. The authors of the current study emphasize that their observational design permits only speculation about the mechanisms behind the associations observed.