6. Functional difficulties associated with ADHD.
Studies for example, have shown that ~50% of children with ADHD have Developmental Co-ordination Disorder (DCD) as well (Gillberg, 1998). In a study of seven-year old Swedish schoolchildren, 1.2% were found to present with a combination of severe pervasive hyperactivity and various motor control and perceptual dysfunction (Gillberg et al, 1982). All these children were said to have 'deficits of attention, motor control and perception' or DAMP. This is a definition adopted by researchers and clinicians in certain countries and is not an official ICD-10 or DSM-IV diagnosis.
The overlap of difficulties found in children with ADHD also extends to other functional areas for example impairments in socialisation and communication. Greene et al (1996) investigated the rate of 'social disability' in children with ADHD and described 22% of their sample as 'socially disabled'. They suggested that most children with ADHD had some social disability and that there was a subgroup in whom these problems were particularly severe. Ehlers and Gillberg (1993) point out that children who meet criteria for ADHD may also met the full criteria for Asperger syndrome. In another study, 21% of children with severe ADHD met the full criteria for Asperger syndrome and 36% showed 'autistic traits' (Fitzgerald and Corvin, 2001). Children with Asperger's syndrome are more likely than autistic children to have co-morbid ADHD and from clinical experience are also quite likely to present with early features which can lead to an initial diagnosis of ADHD (Baird et al, 2001). Gillberg and Gillberg state that not only do most of the children diagnosed with Asperger's syndrome meet criteria for DAMP (1989b) but children with attention disorders often have mild autistic symptoms (Gillberg, 1992) and autistic features are present in at least half the cases with severe DAMP (Gillberg, 1995; Gillberg and Gillberg, 1989a).
Learning difficulties, in particular specific reading difficulties, are common in children with ADHD (Cantwell and Scatterfield, 1978; Lambert and Sandoval, 1980). Approximately one third have specific problems in spelling, reading and mathematics, unaccounted for by low intelligence (Szatmari et al, 1989). In addition to this there may be poor handwriting, general problems with organization and developmental delays in language.
