title: Developmental dyslexia: predicting individual risk.
abstract: BACKGROUND
  Causal theories of dyslexia suggest that it is a heritable disorder, which is the outcome of multiple risk factors. However, whether early screening for dyslexia is viable is not yet known.
  
  
  METHODS
  The study followed children at high risk of dyslexia from preschool through the early primary years assessing them from age 3 years and 6 months (T1) at approximately annual intervals on tasks tapping cognitive, language, and executive-motor skills. The children were recruited to three groups: children at family risk of dyslexia, children with concerns regarding speech, and language development at 3;06 years and controls considered to be typically developing. At 8 years, children were classified as 'dyslexic' or not. Logistic regression models were used to predict the individual risk of dyslexia and to investigate how risk factors accumulate to predict poor literacy outcomes.
  
  
  RESULTS
  Family-risk status was a stronger predictor of dyslexia at 8 years than low language in preschool. Additional predictors in the preschool years include letter knowledge, phonological awareness, rapid automatized naming, and executive skills. At the time of school entry, language skills become significant predictors, and motor skills add a small but significant increase to the prediction probability. We present classification accuracy using different probability cutoffs for logistic regression models and ROC curves to highlight the accumulation of risk factors at the individual level.
  
  
  CONCLUSIONS
  Dyslexia is the outcome of multiple risk factors and children with language difficulties at school entry are at high risk. Family history of dyslexia is a predictor of literacy outcome from the preschool years. However, screening does not reach an acceptable clinical level until close to school entry when letter knowledge, phonological awareness, and RAN, rather than family risk, together provide good sensitivity and specificity as a screening battery.
authors.affiliation: University of Oxford, Oxford, UK.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Thompson
authors.affiliation: University College London, London, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Hulme
authors.affiliation: University of Leeds, Leeds, UK.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Nash
authors.affiliation: Royal Holloway, London, UK.
authors.forename: Debbie
authors.initials: D
authors.lastname: Gooch
authors.affiliation: University of York, York, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Hayiou-Thomas
authors.affiliation: University of Oxford, Oxford, UK.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Snowling
mesh_terms: D002648:Child; D002675:Child, Preschool; D004410:Dyslexia / Q000175:diagnosis*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D007802:Language; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D011379:Prognosis; D012307:Risk Factors
keywords: Familial (family) risk; dyslexia; early identification; executive motor; language skills; reading disability
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