Skovgaard et al., Curr Res Current Research in Psychiatry 2021; 1(2):24-26.

Commentary

The epidemiology of mental disorders in very early childhood: What can we learn from recent research?

Anne Mette Skovgaard1, Susanne Vinkel Koch2,3*

1National Institute of Public Health, The significance of the first years of living in determining mental health later in life has been University of Southern Denmark, acknowledged since the early psychoanalytic approaches to the understanding of mental illness Copenhagen, Denmark delivered by Sigmund and , Rene Spitz and John Bowlby [1,2]. Empirical research since 2Department of Child and Adolescent then has documented the early childhood origin of most mental disorders seen in older children Psychiatry, Zealand Region, Denmark and adolescents [3,4]. Birth cohort studies have provided evidence on the interplay of genes and 3Institue of Health Sciences, University environment from early stages of prenatal life [5-7] and the longterm influences of pre-and perinatal of Copenhagen, Denmark risk factors [3,8,9]. Also, studies of general population birth cohorts have identified infancy precursors of mental disorders diagnosed in preschool and school age [10-13].

*Author for correspondence: Epidemiological research from the last decades has documented the public health burden of Email: [email protected] mental health problems and disorders in older children, adolescents and adults [2,14-17], and highlighted the needs of preventive intervention in early childhood [18]. However, the knowledge Received date: April 19, 2021 on the developmental epidemiology of mental disorders in early ages is still limited, and the scientific Accepted date: May 13, 2021 foundation of preventive intervention correspondingly scanty [1,19,20]. Until recently, epidemiological research in mental disorders in younger children has been Copyright: © 2021 Skovgaard AM, hampered by limitations in measures of diagnostic assessment. Over the last decades, however, et al. This is an open-access article validated measures have increasingly been used, both in studies of clinically referred childen (e.g. distributed under the terms of the Lavigne et al. [21]; Frankel et al. [22]) and in community studies (e.g. Skovgaard et al. [23], Creative Commons Attribution License, Skovgaaard et al. [24], Wichstrøm et al. [25]), and the existence of impairing clinical syndromes which permits unrestricted use, distribution, and reproduction in any in children down to the ages of 0-3 years has been established [26], as reflected in the international medium, provided the original author classification schemes: The ICD-10 Classification of Mental and Behavioral Disorders [27]; the and source are credited. Diagnostic Statistical Manual of Mental Disorders, DSM-5 [28] and the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood, DC: 0-3 [29] and DC:0-5 [30]. The first general population study that includes the range of mental disorders in children below the age of two years was based on The Copenhagen Child Cohort CCC2000 [9,24]. In a random sample (N=211) nested in the cohort (N=6090) of 1½ year old children from the general population in Copenhagen County (the suburbs of Copenhagen), the prevalence of any ICD-10 mental disorder was found to be 16.0%, 95% CI (11.9, 22.1). Disorders within the area of emotions, behaviour, eating and sleep were the most common among these children, whereas developmental disorders and disorders of hyperactivity and inattention were found in 2.8 % CI (1.1, 6.1) and 2.4 % CI (0.8, 5.4), respectively [24]. The diagnostic distribution and patterns of risks found in children aged Citation: Skovgaard AM, Koch SV. The 1½ years were found similar to results from community studies of older children [3]. Also, neuro- epidemiology of mental disorders in developmental disorders were found associated to pre-and perinatal biological risk factors, whereas very early childhood: What can we psycho-social risks in the family were highly asociated with emotional, behavioural, eating and sleep learn from recent research?. Curr Res disorders [24]. Within the first years of living, the CCC2000 study identified specific infancy risk Psychiatry. 2021; 1(2):24-26. trajectories of neuro-developmental problems and problems of parent-child relations and emotional and behavioural disorders [31,32], findings in line with results from other recent birth cohorts [11- 13].

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Curr Res Psychiatry 2021; 1(2):24-26. 24 Citation: Skovgaard AM, Koch SV. The epidemiology of mental disorders in very early childhood: What can we learn from recent research?. Curr Res Psychiatry. 2021; 1(2):24-26.

The results from the CCC2000 were included in a recent born small for gestational age were associated with an overall increased research review with a meta-analysis of the international prevalence risk of mental disorders, and in particular developmental disorders, and comorbidity of mental disorders in children between 1 and 7 and so were maternal smoking in pregnancy, young maternal age and years [20]. The review covered the period 2006-2020 and included old paternal age [35]. ten studies from eight countries (USA, Iraq, Brazil, Romania, Spain, Among 0-3 years old referred to hospital, disorders of feeding the Netherlands, Norway, Denmark) with data on a total of 18,282 and eating (FED) were diagnosed with a cummulative incidence of children. The overall pooled prevalence of mental disorders was 0.2% [36]. Premature birth, being born small for gestational age and 20.1%, 95% CI (15.7, 25.4). The review included only diagnoses with congenital malformations were associated with a three to nearly that were reported in at least four studies, which left pervasive five fold increased risk of FED. While boys have a higher risk of developmental disorders/autism-spectrum disorders, specific overall mental disorders, and in particular for neuro-develomental developmental disorders (e.g. disorders of language development) disorders [35], girls showed a higher risk of FED. Also, being born in and general developmental disorders (e.g. intellectual disability) families of immigrant status and being the firstborn were associated out of the analyses. Among the included disorders, oppositional with increased risk of FED in the first years of living [36]. defiant disorder had a pooled prevalence of 4.9%, 95% CI (2.5, 9.5); attention-deficit hyperactivity disorder 4.3%, 95% CI (2.5, 7.2); Conclusions anxiety disorders 8.5%, 95% CI (5.2, 13.5), and depressive disorders 1.1%, 95% CI (0.8, 1.6). Comorbidity, e.g co-ocurrence of two or Research on the developmental epidemiology of mental disorders more of any of the included mental disorders, was estimated at 6.4%, in the first three years of living is still in its infancy. However, the 95% CI (1.3, 54.0). Based on their review, the authors concluded research findings published so far highlight that early emerging that the epidemiology of mental disorders in children younger than psychopathology and impairing mental disorders at ages 0-3 years 7 years is still under-researched [20]. are as frequent as in older ages, showing patterns of comorbidity and risk factors that need to be addressed in clinical settings as well as in Denmark is a country of unique possibilities regarding future research. More research in this field is needed, but so far, the epidemiological research, mainly due to the potentials of population current state of knowledge points to complex causal mechanisms of registries that cover all citizens across life and includes all patient risks and early developmental trajectories involving both perinatal contacts to public hospitals with systematic recordings of diagnoses and psychosocial risk factors that have to be taken into account in [33]. 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