Risk factors for ADHD
Worldwide, attention-deficit hyperactivity disorder (ADHD) affects between 5-8% of children and adolescents, and 4% of adults.
Until a few years ago, it was believed that children outgrow ADHD in adolescence. While hyperactivity often does diminish during the teenage years, it’s now known that symptoms of ADHD can continue into adulthood. In fact, up to 65% of children with ADHD will continue to exhibit symptoms in adulthood. In many of these adults, ADHD may still have a negative impact on their functioning in all aspects of life and society.
Males are far more likely to be diagnosed with ADHD, with the ratio of males to females with ADHD about 3:1. However, ADHD tends to be under-diagnosed in girls as they more frequently present with the inattentive type. This type of ADHD is more difficult to identify than the hyperactive/impulsive type because the individuals don’t present with marked behavioural problems.
In certain conditions, i.e. Tourette’s syndrome, certain genetic disorders and foetal alcohol syndrome, a higher incidence of ADHD is found.
Risk factors that have been linked to attention-deficit hyperactivity disorder (ADHD) include:
- Male gender: Boys are three times more likely than girls to develop ADHD.
- Family history: A person has a three to five times increased risk for ADHD if a parent, sibling or child has the condition. Therefore, there seems to be a strong genetic link.
- Smoking during pregnancy: Children whose mothers smoked while they were pregnant are twice as likely to develop ADHD. Alcohol and drug use during pregnancy may also increase a child’s risk for this condition.
- Exposure to environmental toxins: Some studies have linked ADHD to lead, manganese and mercury exposure. Exposure to certain pesticides may also play a role.
- Adverse psychosocial conditions: Stress during pregnancy has been linked to an increased risk for ADHD in offspring. Early childhood trauma has also been linked to ADHD.
- Birth complications: Very preterm, extremely preterm, very low birth weight and extremely low birth weight babies seem to have a higher risk of developing ADHD.
Reviewed by Prof André Venter, Head: Clinical Department of Paediatrics and Child Health, Faculty of Health Sciences at the University of the Free State. MB ChB, MMed, PhD (Canada), DCH, FCP (Paed) SA. July 2018.
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