Mental health problems and psychopathology in infancy and early childhood. An epidemiological study

The thesis includes seven published papers and an overview concerning the epidemiological aspects of mental health problems and psychopathology in children aged 0-3 years. The research behind the thesis focuses at psychopathology in the first years of life. The aim has been to investigate phenomenology, prevalence, risk factors and predictors, in order to contribute to the knowledge about early developmental psychopathology, and improve the scientific foundation for identification and treatment of mental illness of infants and toddlers, and optimize the foundation for prevention of psychiatric illness in early life. The Copenhagen Child Cohort CCC 2000 was established with inclusion of 6090 children born in year 2000. The cohort was described at baseline with data from Danish National registers and prospective data on mental health and development collected by health nurses at home visits. At 1½ years of age a subpopulation was thoroughly investigated regarding child psychiatric illness, in a random sample prevalence study and a case-control study nested in cohort, with cases being children of health nurse concern in the first ten months of living. Mental health disorders were identified in 18% of 1½ year-old children from the general population. The prevalence and distribution of main diagnostic categories correspond to results from studies of older children. Disorders of neurodevelopment (mental retardation, disorders of psychological development and ADHD) were associated with pre- and perinatal biological risks and predictors were deviant language development and impaired communication, recorded by health nurses in the first ten months of life. The findings correspond to results from studies of older children and adolescents and point to an earlier emergence of neurodevelopmental psychopathology than has been described hitherto. Risk factors of emotional, behavioural and eating and sleeping disorders were psycho-social adversities in parents, and parent-child relationship disturbances seem to be the key mediator in the risk mechanisms. Risk factors of relationship disorders at child age 1.5 years can be identified before the birth of the child, and predictors can be identified by health nurses from birth to 10 months. In the general child health surveillance between birth and ten months, community health nurses are able to identify risk factors and predictors of child mental disorders at 1.5 years, and by a global and unspecific screen, health nurses identify one fourth of children diagnosed with a mental disorders at age 1½ year. The incidence of mental health disorders including mental retardation diagnosed at hospital in the first three years of life was 2%. Sex differences known from studies of older children were demonstrated in children referred to hospitals, with neurodevelopment disorders more often diagnosed in boys, and eating disorders more frequent in girls.

For the first time it is shown in a general population study, that children as young as 1.5 years may suffer from mental illness as older children do. Risk factors and predictors of mental illness can be identified in the first ten months of life, and the association of risks found in studies of older children seem to operate already from birth. The results point to the potentials of mental health screening and intervention in the existing child health surveillance.

The current longitudinal study of CCC 2000 in preschool and school age will expand the present findings and further elucidate the significance of the first years of life regarding child mental health. Future research in this area should include the study of measures to screen and intervene towards mental health problems in infancy within the general child health surveillance.