The children within ALSPAC with diagnoses of ASD and ADHD have been identified from 3 independent sources: (a) the clinical records of all children in the cohort investigated for a suspected developmental disorder by a multi-disciplinary assessment (b) the national educational database in England (PLASC) which identified all children in state schools (over 90% of children) who were needing special educational provision in 2003 and c) the Development and Well Being assessment (DAWBA), applied in the ALSPAC 9 yr research clinic. A total of 86 children were identified with ASD and 175 with ADHD by 11 years of age.

ALSPAC has repeatedly asked questions about children's sleep patterns from birth through to adolescence. A multi disciplinary ALSPAC sleep interest group (Alan Emond, Peter Fleming, Pete Blair, Esther Crawley, Raghu Lingam, Paul Gringras, Nicola Scott and John Henderson) have been overseeing the data. Now that the 16 year old data is available, the dataset is complete through childhood and can be used to answer four crucial sleep-related health questions:

1. What are 'normal' sleep patterns of children in the UK?

We will describe sleep patterns from birth to 16, using latent class analyses and trajectory modelling, and then explore the impact of factors such as co-sleeping, social adversity, parental smoking and alcohol use. This will cover areas including:

Are poor sleepers in infancy, still poor sleepers in adolescence? What impact does social adversity have on sleep patterns?

2. What is the association between short-sleepers and ADHD?

The association between decreased sleep time in infancy and later diagnoses of ADHD is unclear.(1) ALSPAC data allows us to define all the short sleepers in infancy including those that drop their daytime nap early, and then follow-up those children that eventually receive a diagnosis of ADHD. This 'chicken and egg' question could help to provide an early marker of ADHD, help understand causes of ADHD and offer a potential target for early treatment.

3. Is there an association between long-term iron stores, sleep disturbance and ADHD?

Low iron stores, as measured by peripheral ferritin levels have been associated with both restless sleep, and symptoms of ADHD.( 2) The extent of this relationship is still unknown. If it is real, then one would expect increased numbers of children with ADHD to have lower levels of ferritin. Sleep, ferritin levels and ADHD have already been measured within ALSPAC offering a chance to explore another potentially treatable cause of ADHD.

4. What is the relationship between sleep disturbance, breast-feeding and autistic spectrum disorders?

Exciting new genetic research has suggested physiological reasons why sleep problems are so much more common in children with autism than in the general population. (3) Dr Gringras has proposed that due to certain hormones related to early brain development, theoretically, it is non-breast fed infants that should be at increased risk for sleep disorders and autism. ALSPAC, through its questions on early feeding, sleep and later diagnoses of autism has already gathered the data necessary to explore this fascinating question with potentially huge public health implications.

Variables required

In addition to the sleep variables to which we already have access , we are requesting questionnaire data:

1.developmental diagnoses from the IDI database-11 yrs

2. DAWBA data- 7,10 yrs

3.SDQ data-4,6,8, 9, 11yrs

4. SCDC data- 4.5, 6.5, 7.5 yrs

5. IQ data- 8 yrs

6. lab data: ferritins from CIF- 8months,18 months

Project team

The analyses will be supervised by Prof Alan Emond and Dr Paul Gringras, supported by the ALSPAC sleep interest group.

The ALSPAC database is huge, and we a will need a considerable amount of statistical support as this will be the first time all ALSPAC sleep data will have been divided into latent classes, to track each individual child's sleep history and find common patterns. Dr Pete Blair, a senior research statistician at Bristol University, has already worked with aspects of the ALSPAC data and been part of many key publications. His familiarity with the data is a huge advantage, as is his interest in childhood sleep. Pete will be undertaking the analyses, assisted by academic F2 trainee Dr Joanna Humphries.

Whilst Prof Emond, Dr Gringras and the rest of the sleep interest group already have enough ring-fenced academic time to carry out the above work without funding, none of them have Dr Blair's statistical expertise or familiarity with the ALSPAC dataset. We are requesting funding from The Guys Hospital Charitble Trust for Dr Blair's salary for 6 months and a small 'data buddy' fee to gain access to all the cleaned ALSPAC variables required. The only non-pay resources requested are the travel costs associated with meetings of the researchers in London and Bristol. No overheads are included.

The interpretation and writing up of the results will be undertaken by the ALSPAC sleep interest group within existing academic sessions.

REFERENCES

1.Gringras P. Sleep disorders and ADHD. In Taylor, E editor. ADHD. Mackeith Press 2007

2.Konofal E, Lecendreux M, Deron J, Marchand M, Cortese S,Zaim M, Mouren MC, Arnulf I. Effects of iron supplementation on attention deficit hyperactivity disorder in children.

Pediatr Neurol 2008;38:20-26.

3.J Melke, H Goubran Botros, P Chaste, C Betancur, G Nygren, H Anckarsa , M Rastam,O Stahlberg, IC Gillberg, R Delorme, N Chabane, M-C Mouren m,Simeoni, F Fauchereau, CM Durand, F Chevalier, Drouot, C Collet,J-M Launay M Leboyer C Gillberg T Bourgeron and the PARIS study. Abnormal melatonin synthesis in autism spectrum Disorders. Molecular Psychiatry (2008) 13, 90-98