Title: Increased diagnosis of developmental disorders: Are there really more children with Autism, Dyslexia, or ADHD?
Funder: Economic and Social Research Council

Abstract: Studies have shown that the number of children diagnosed with childhood developmental disorders, which include dyslexia, autism spectrum disorders, and attention deficit hyperactivity disorders (ADHD) has risen sharply in the western world over the last twenty years. Most experts, clinicians and epidemiologists, largely attribute this to changes in diagnosis rates and greater awareness of the conditions. They argue that the number of children with symptoms of these conditions has remained largely stable, it is just that more children are identified and diagnosed today than ever before. This is due to shifts in diagnostic criteria so that more children are included in the categories, and the changing cultural context which emphasises differences. On the other hand, many lay people affected by, caring for, or working with children with developmental disorders, and some researchers, believe that such explanations may not tell the whole story. They have argued that the rising prevalence may reflect a real increase in the number of children with difficulties symptomatic of the disorders. Many have suggested that rising prevalence could be underpinned by changes in environmental causal factors. Our analysis will examine whether increases in the numbers of children diagnosed have been accompanied by increases in behaviours and impairments symptomatic of these conditions, or whether symptom levels have remained constant with diagnosis increasing, (so the labels are simply applied to more children). All three conditions are relevant because all are classed as developmental disorders, with debate over the boundaries of the disorder, and even the existence of a "disorder" at all. The children in our studies will be from the Avon Longitudinal Study of Parents and Children, (ALSPAC), where children were born in 1990 or 1991, and the Millennium Cohort Study (MCS), where the children were born ten years later, in 2000 or 2001. As we expect, there are far more children diagnosed autism and ADHD in the later MCS study. Data from these two studies will allow us to compare the number of seven year old children with symptoms of each disorder in 1998 to the number with symptoms in 2007. This will show whether the rises in diagnosis are reflected by a rise in number of children with underlying symptoms Crucially, both studies have recorded similar diagnostic, cognitive and behavioural measures, making a direct comparison possible. It is important to determine whether there is an underlying increase in symptoms, because if so, environmental or social factors are probably responsible and could become targets for intervention and or prevention. Boys are more likely than girls to suffer from autism, dyslexia and ADHD. But if girls and boys are suffering from an equal level of difficulties (the same symptom levels) our previous work suggests that the boys' difficulties are more likely to be recognised than the girls'. Are boys are more likely to be diagnosed, even when girls we compare them to have similar levels of symptoms? Our second aim is to establish whether boys are more likely than girls to receive an ASD or ADHD diagnosis, or be identified as dyslexic, regardless of symptom levels. This should provide clinicians and educators with important information about which children are missing out on services designed to help them. Our final aim is to explore overlap in symptoms between the conditions. Much research suggests that some children share symptoms of autism, dyslexia and ADHD. This had led scholars to question the diagnostic criteria for developmental disorders in their current configuration. We will look at which disorders children with co-occuring symptoms are likely to be labelled with. This is extremely important because the diagnostic label may determine the interventions children receive. .


Research activity codes: 2.4 SURVEILLANCE AND DISTRIBUTION
Health categories: MENTAL HEALTH