One in four Lisbon preschoolers shows signs of mental health difficulties

A study of children in the Lisbon metropolitan area links early emotional and behavioural difficulties to socioeconomic conditions, family structure and lack of sports participation.

Nearly one in four preschool children in the Lisbon metropolitan area shows signs of early mental health difficulties, according to research published in BMC Public Health that adds rare community-based evidence to a field where Portugal has had little data. The study, led by Rita Gonçalves of the National School of Public Health at NOVA University Lisbon, found that 23.6% of children aged four and older scored in the borderline or abnormal range on a widely used parent-completed screening tool. The findings suggest that psychological strain can be visible well before children enter formal schooling.

The research drew on 760 children recruited through primary health care centres between May 2022 and December 2024, with analysis focused on 453 children aged at least four whose caregivers completed a valid Strengths and Difficulties Questionnaire. The SDQ is a longstanding screening instrument that asks parents about emotional symptoms, conduct problems, hyperactivity, peer difficulties and prosocial behaviour. Previous research published in Pediatrics has shown that the questionnaire can be a valid way to identify psychosocial problems in preschool children, although some subscales are not reliable enough to guide treatment decisions on their own.

Beyond the headline prevalence figure, the study points to clear social and behavioural patterns. After adjusting for other factors, children in households with monthly income of roughly €750 to €1,500 had higher odds of elevated difficulty scores than those in households earning more than €1,500, while children living in extended or other non-nuclear family arrangements also faced increased odds. The strongest association was with physical activity: children who did not take part in sports were far more likely to score in the concerning range than those who did.

The data also showed that children with an immigrant background were more likely to experience socioeconomic disadvantage, greater screen exposure and less sports participation, and they were more often reported to have peer relationship problems. But once the researchers accounted for income, family structure and other social factors, the apparent gap in overall mental health difficulties largely disappeared. That suggests the disadvantage is driven less by migrant status itself than by the circumstances in which these children are growing up.

For public health practitioners, the findings strengthen the case for early identification in primary care. The study authors argue that routine paediatric visits could be used to flag families needing extra help and to connect them with mental health and social support services. That matters because the research was based on a general community sample, not on children already in treatment, indicating that the concerns are present in the broader preschool population rather than only among those already known to services.

The study, like all cross-sectional research, cannot prove cause and effect. It captures one point in time, so it cannot show whether low income, family structure or lack of sport leads to mental health difficulties, or whether those factors simply cluster together around the same families. Even so, the message is clear: emotional and behavioural difficulties are already visible at age four for many children in Lisbon, and the conditions most closely linked to them are social and modifiable.