Title: Structure and risk of Internalizing Problems in preschool boys and girls in São Paulo, Brazil
Description: (1) Problem: Research on internalizing problems in young children is scarce despite evidence that children can have problematic internalizing symptoms as early as preschool years 1-3. In preschoolers, it is difficult to observe internalizing problems directly. While they are not overtly socially disruptive behaviors4, they have negative consequences in their daily lives, can continue in adolescence, and potentially develop into disorders in later years 5-7. Studying internalizing problems in preschoolers is of particular importance in Low- and Middle- Income Countries (LIMC) since there may be a higher prevalence of common risk factors (such as parental psychopathology, violence, and neglect) than in High-Income Countries. According to the World Health Organization, in 2015, Brazil (a LMIC) ranked first in the past-year prevalence of anxiety (9.3%) and fifth in the prevalence of depression (5.8%) 8,9 in people aged 15 years or older. Preschoolers in São Paulo, Brazil, have an estimated six-month prevalence of internalizing problems of 25.4%.

There are few estimates in other regions of Brazil, partly due to the lack of validated scales to measure them. In addition, it is unknown if the disparate rates by sex (females have at least twice the rates of males) seen in adolescence and adulthood could be detected at an early age. This dissertation's primary goal is to advance our understanding of internalizing problems in preschoolers in Brazil, a LMIC that is highly affected by psychopathology and associated disability. (2) Methods: First, a systematic literature review on the topic in LMIC was conducted. Second, data from the Preschool Mental Health Survey (the PreK Survey), with a representative sample (n=1,292) of preschoolers aged 4 to 5 years old and their caregivers in the city of Embu das Artes, São Paulo, was used to: (a) do Confirmatory Factor Analysis (CFA) of the internalizing section of a worldwide known assessment tool for problem behaviors in preschoolers (the Child Behavioral Checklist CBCL 1.5-5); and (b) conduct multigroup CFA to examine differences by sex in the structure of internalizing problems.

Finally, Generalized Linear Models for complex data were used to assess the risk of internalizing syndromes by parental depression, severe physical or verbal violence, and low-quality time with parents differentially by sex of the preschoolers. (3) Conclusions: From the literature review, a scarcity of research on internalizing problems of preschoolers was found in LMIC. Hence, (a) only a few risk factors, mainly parental psychopathology, have been explored in most LMIC; and (b) the large majority of studies in LMIC in the Americas use the CBCL 1.5-5 or other scales not validated for their study population. From the multigroup CFA, it was concluded that (a) the construct of internalizing problems in the CBCL 1.5-5 is valid in preschool boys and girls in São Paulo, Brazil, and in similar contexts, supporting previous and future studies on the topic; and (b) the main syndromes of internalization are "Anxiety/Depression" and "Emotionally Reactive." From the assessment of risk, it was concluded that (a) the main risk factor for internalizing problems in preschoolers in Brazil is parental depression; (b) externalizing problems are highly correlated with internalizing problems and are the main source of confounding; (c) there were no significant differences by sex in the prevalence of risky exposures, but they were all significantly associated with internalizing problems; (d) there were significant differences by sex in the mean scores of internalizing syndromes, and in the associations of risky exposures and internalizing problems, highlighting the need of a differential approach to primary prevention and treatment in preschool boys and girls.