Eur J Pediatr (1991) 150: 570-574 034061999100109L EuropeanJournalof Pediatrics 9 Springer-Verlag 1991 Intelligence, motor skills and behaviour at 5 years in early-treated congenital hypothyroidism P. W. Fuggle, D.B. Grant, I. Smith, and G. Murphy* Institute of Child Health, 30, Guildford Street, London WCIN 1 EH, United Kingdom Received August 6, 1990 / Accepted December 13, 1990 Abstract. The cognitive functioning, motor skills and be- haviour of 5-year-old children with early-treated congen- ital hypothyroidism was assessed. The study group was 57 children with congenital hypothyroidism (CH) diag- nosed by neonatal screening in N.E. and N.W. Thames regions between 1978 and 1981 along with 51 non-affect- ed controls matched for age, sex, social class and lan- guage background. Small differences in I.Q. and be- haviour between the patients and the controls were not statistically significant. However, children with CH showed significant deficits in motor skills (M 79.9 SE 3.7) compared to the controls (M 99.8 SE 4.0) (P= 0.0003). Deficits were particularly marked for balance. In addition, children with more severe hypothyroidism at diagnosis (Plasma thyroxine < 20 nmol/l) did signifi- cantly less well in respect to I.Q. and motor skills than those with less severe hypothyroidism (plasma thyroxine > 60nmol/1). These findings provide further evidence for the importance of the severity of hypothyroidism in determining the outcome for intelligence and motor skills in children with early-treated congenital hypo- thyroidism. Deficits in motor skills, particularly in rela- tion to balance, suggest that early impairment of the ves- tibular system may occur despite early treatment. Key words: Hypothyroidism - Intellectual development - Motor skills affected children start treatment within the first few weeks of life. It appears that screening programmes have been successful in reducing the most severe effects of CH on neuro-psychological development [5, 13, 15], however it remains possible that subtle learning difficul- ties, clumsiness and behaviour problems may occur with greater frequency in early-treated CH children than in the general population [5]. This paper represents the results of psychological assessments carried out at 5 years of age on a group of 57 children with early-treated CH, 51 of whom were matched with nonaffected control children. The children with CH were born between 1978 and 1981 and had been identified by neonatal screening in the North Thames Health Regions of the United Kingdom. Details of the diagnosis and early treatment of this group of patients have been reported previously [10]. Assessment of their psychological progress at 3 years of age suggested that cognitive functioning was within the average range but that the children with CH showed a small deficit com- pared with controls. This deficit was more marked for children with more severe hypothyroidism at diagnosis. In addition, the patients were significantly slower than controls at a speeded motor skills task [13]. In the pre- sent study this group of children have been reassessed to see whether these psychological deficits and the relation- ship to severity of hypothyroidism persisted to school age. Introduction Screening programmes for the detection of congenital hypothyroidism (CH) are now well established in the United Kingdom [7] and in most countries with ad- vanced health care systems [1] and the great majority of Offprint requests to: P. W. Fuggle * Current address: Institute of Psychiatry, London Abbreviations: CH = congenital hypothyroidism; T~ = thyrox- ine Methods Patients Of the original sample of 76 children detected by screening, 57 completed full assessments at 5 years of age and 51 of these were matched with a non-hypothyroid control for age, sex, social class and language spoken at home. These controls were either children assessed at 3 years as part of the same study or were selected at 5 years from primary schools in the same area as the children with CH. Of the 57 children with CH assessed in the present study, 44 had been seen at 3 years [13] and 46 at 1 year [10]. Of the 19 CH children not assessed at 5 years, 10 had moved abroad or to a different region in the United Kingdom 6 did not attend repeated assessment appointments and 3 completed only part of the assess- ment.