Attention Deficit Hyperactivity Disorder (ADHD) otherwise known as Hyperkinetic disorder (ICD 10) is an extremely disabling condition, affecting 1.4-6% of children. It is now the commonest reason for follow-up in Child and Adolescent Mental Health Services as well as being seen in Community Child Health Services. Behavioural, social and educational problems as well as increased rates of adult difficulties including criminality and drug misuse are associated with ADHD in children with normal intelligence. In contrast, virtually nothing is known about ADHD in children with learning disability (LD/mental retardation) as sub average intelligence (IQless than 70) has traditionally been used as an exclusion criterion in studies of ADHD. Neither the DSM-IV nor the ICD-10 gives detailed consideration to the diagnosis of ADHD/Hyperkinetic disorder among children with LD.

At one time, clinical lore suggested that ADHD did not occur in children with LD, and any inappropriate behaviour children with LD showed was secondary to mental impairment. That view is not supported by current evidence. More recent studies have shown that ADHD occurs more commonly in these children but may be underdiagnosed due to issues such as '' diagnostic overshadowing'', the tendency by which clinicians tend to overlook additional psychiatric diagnosis once a diagnosis of learning disability is made; or ''masking'' in which the clinical characteristics of a mental disorder are masked by a cognitive, language or speech deficit.While available evidence suggests that ADHD may be more common among children with learning disability, research has been hindered as most studies of ADHD in children with LD do not use standardised diagnostic interviews and criteria. Also this sub-group of children with ADHD and learning disability are excluded from virtually all aetiological and treatment studies. Thus it is not known whether the clinical presentation, pattern of correlates and aetiology of ADHD differs in children with learning disability. This may have ethical implications as not much is known about the diagnosis and treatment in this group of children and hence they are frequently undiagnosed and untreated.

Although there is evidence that ADHD does occur in those with LD a crucial clinical issue is whether or not ADHD in this group is the same entity as that found in those without learning disability; that is can those with both ADHD and LD be viewed as having "true" ADHD. As this sub-group is almost always excluded from research, it remains unknown whether they are similar to children with ADHD and normal IQ in terms of clinical and aetiological correlates. Our preliminary pilot study analyses using a sample of children with ADHD with low IQ test scores showed that lower IQ, is associated with increased ADHD symptom severity and conduct disorder symptoms. This suggests that ADHD and LD may represent a clinically more severe variant of ADHD.On the basis of pilot data, we hypothesise that children with ADHD and LD will show a similar clinical presentation and pattern of genetic and psychosocial correlates to those found in children with ADHD and IQ within the normal range. If our hypothesis is correct, then children with ADHD and LD are likely to benefit from stimulant and other treatments that are known to be effective in those with ADHD without LD and our work will provide impetus for therapeutic trials in this important and disadvantaged group. Moreover, the findings will further highlight that children with ADHD and learning disability should not necessarily be excluded from aetiological and other clinical studies.

AIMS OF THE STUDY:

The aim of this study is to

1) Collect and comprehensively assess a sample of 100 children with ADHD and learning disability.

2) Compare this group with two other groups-a well-characterised sample of children with ADHD who have normal intelligence (IQgreater than 70) that has already been collected and a control group of children with low IQ alone on a) clinical characteristics b) genetic and psychosocial correlates that are known to be associated with ADHD.

The control group of children with low IQ and no clinical comordity have been difficult to recruit from a clinical setting and the ALSPAC would be ideally placed to provide the clinical and cognitive data required for this group of children.

Current data requested:

ADHD -

DAWBA data on Attention & Activity from parent questionnaires at ages 91mths and 128 months

DAWBA data on Attention, Activity and Impulsiveness from teacher questionnaires at Yr 3 & Yr 6

Antisocial Behaviour -

DAWBA data on Awkward & Troublesome Behaviour from parent questionnaires at ages 91mths and 128 mths

DAWBA data on Awkwardness & Troublesome Behaviour from teacher questionnaires at Yr 3 & Yr 6

Antisocial Behaviour questions from Focus@8 and Focus@10 from the child

Cognitive measures -

WISC IQ measure from Focus@8, including digit span subtest, full scale IQ, pe rformance IQ and verbal IQ measure

Other Measures:

Demographic measures -

Sex,

Age at each assessment,

whether from a multiple birth

Social class (maternal education and housing type),

Ethnicity.