A large-scale, long-term study of Attention Deficit Hyperactivity Disorder (ADHD) has prompted experts to re-evaluate how they diagnose and treat the condition. ADHD is a common, chronic, behavioural disorder characterized by inattention, hyperactivity and impulsivity that is though to affect some 5-10% of school-age children worldwide. It has been associated with cognitive defects, particularly with working memory and inhibition which have been linked to overall intelligence and academic achievement. However, the study showed that these deficits were only present in about half of the adolescents diagnosed with ADHD. The study of 457 children in Finland tracked them from the early fetal period to adolescence (16 to 18). Despite the fact that children in Finland are rarely given medicine for the condition its prevalence, symptoms, psychiatric comorbidity (other mental-health problems experienced by the children) and cognition was the same as in the U.S. where children are much more likely to get drug treatment for the condition leading the researchers to pose questions about the effectiveness of pharmacological treatment. Other findings from the study included the fact that hyperactivity and impulsivity declined with age while inattention became more prominent. Two-thirds of the children continued to exhibit significant levels of inattentiveness and impairment into adolescence. ADHD was associated with increased rates of other psychiatric problems such as depression, anxiety, oppositional behaviour and conduct disorders and the rate of post-traumatic stress disorder was also higher in the children with ADHD. The researchers argued that ADHD should be regarded not as a discrete medical condition but as being at one end of a spectrum of behaviour in the same way that variables such as IQ, height and weight vary across a spectrum.
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