Background: Children younger than 7 years can develop mental disorders that might manifest differently than in older children or adolescents. However, little is known about the prevalence of mental disorders at this early age. Methods: We systematically searched the literature in the databases Web of Science, PsycINFO, PSYNDEX, MEDLINE, and Embase to identify epidemiological studies of community samples published between 2006 and 2020. A series of meta‐analyses was conducted to estimate the pooled worldwide prevalence of mental disorders in general, specific mental disorders, and comorbidity in young children. Results: A total of ten epidemiological studies reporting data on N = 18,282 children (12–83 months old) from eight countries met the inclusion criteria. The pooled prevalence of mental disorders in general was 20.1%, 95% CI [15.7, 25.4]. Most common disorders were oppositional defiant disorder (4.9%, 95% CI [2.5, 9.5]) and attention‐deficit hyperactivity disorder (4.3%, 95% CI [2.5, 7.2]). The prevalence of any anxiety disorders was 8.5%, 95% CI [5.2, 13.5], and of any depressive disorders was 1.1%, 95% CI [0.8, 1.6]. Comorbidity was estimated at 6.4%, 95% CI [1.3, 54.0]. Conclusions: The literature search reveals that the epidemiology of mental disorders in children younger than 7 years is still a neglected area of research. The findings also indicate that there are a significant number of young children suffering from mental disorders who need appropriate age‐adapted treatment.

Culture is a key determinant of children's development both in its own right and as a measure of generalizability of developmental phenomena. Studying the role of culture in development requires information about participants' demographic backgrounds. However, both reporting and treatment of demographic data are limited and inconsistent in child development research. A barrier to reporting demographic data in a consistent fashion is that no standardized tool currently exists to collect these data. Variation in cultural expectations, family structures, and life circumstances across communities make the creation of a unifying instrument challenging. Here, we present a framework to standardize demographic reporting for early child development (birth to 3 years of age), focusing on six core sociodemographic construct categories: biological information, gestational status, health status, community of descent, caregiving environment, and socioeconomic status. For each category, we discuss potential constructs and measurement items and provide guidance for their use and adaptation to diverse contexts. These items are stored in an open repository of context-adapted questionnaires that provide a consistent approach to obtaining and reporting demographic information so that these data can be archived and shared in a more standardized format. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Human milk is considered the most advantageous source of nourishment for infants. Even though there is no ideal composition of human milk, it still contains a unique combination of components that contribute to brain development. The aim of this review is to provide an overview on the possible correlation of human milk with the neurodevelopment of infants, with a special emphasis on myelination and epigenetic modifications. Research in human milk is a rapidly expanding field and cutting-edge technologies might contribute to identify specific mechanisms underlying the beneficial effects on human milk on neurodevelopment.