Study offers insight into early developmental risk factors for ADHD

Several early developmental factors are associated with an increased risk of ADHD during childhood and adolescence. Maternal stress during pregnancy and unwanted pregnancy may increase the incidence of ADHD symptoms in children, according to research. The duration of breastfeeding was also found to have an impact on the risk and onset of ADHD symptoms.

ADHD is a neurodevelopmental disorder characterized by hyperactivity, impulsivity and problems in sustaining attention that cause impairment in many areas of life. ADHD is partly a hereditary condition, but recent research has shown that environmental factors also play a role in the risk and onset of the disorder.

Jandeh Jallow, a Licentiate of Medicine at the University of Oulu, Finland, shows in her PhD research that maternal stress during pregnancy and unwanted pregnancy can increase the incidence of ADHD symptoms in children. It is also possible that the shorter duration of breastfeeding among postnatal risk factors increases the prevalence of ADHD symptoms.

Previous studies have shown that early risk factors for ADHD include prematurity and maternal substance abuse during pregnancy. In addition to these, there are prenatal and early childhood factors that have been little studied or have conflicting data in previous studies.

In her population-based doctoral thesis, Jallow examined the understudied risk factors for prenatal and early childhood ADHD in a 1986 Northern Finland birth cohort. She investigated whether maternal prenatal inflammation and stress, duration of breastfeeding, and child´s own personality and comorbid psychopathology or psychiatric illness were associated with increased risk of ADHD in childhood and adolescence.

The study found an association between unwanted pregnancy and less than three months of exclusive ja non-exclusive breastfeeding with hyperactive symptoms at age 8. Maternal stress during pregnancy and partial breastfeeding for less than six months were associated with an increased risk of ADHD symptoms at age 16.

The child's own personality profile was also associated with a diagnosis of ADHD in adolescence. The study revealed differences in temperament and personality traits between a healthy control group and those diagnosed with ADHD. Adolescents diagnosed with ADHD being more likely to be novelty-seeking and less self-directed, cooperative, and persistent than those without a diagnosis of ADHD.

The PhD study is one of the first and most representative studies to date of early risk factors for ADHD. The results will be useful in developing preventive measures, as ADHD is associated with a high level of both individual and societal disadvantage.

The number of ADHD diagnoses in Finland has exploded in recent years. As ADHD is also over- and misdiagnosed in some places, the identification of risk factors may provide new tools for a more accurate diagnosis of ADHD in the future.