New study assesses impact of early detection of hearing impairment on children's language skills
The early detection of hearing impairment in babies significantly improves the language ability of affected children in later childhood, a new study led by Dr Colin Kennedy of the University of Southampton has revealed.
The study of 120 children with permanent hearing impairment in the south of England shows that their language skills were stronger at eight years of age if their hearing difficulties had been confirmed before they were nine months old than if they had been confirmed later. However, the study also showed that a hearing impaired child's speech is not greatly benefited by early detection.
One in 750 children in the UK is born with moderate, severe or profound bilateral permanent hearing impairment, which is present at birth in more than 80 per cent of affected children. Such impairments are associated with impeded language acquisition, learning and speech development.
Previous work in Southampton, also led by Dr Kennedy, established that screening of all newborn babies for this condition with a simple bedside screening was effective in increasing the proportion of babies with permanent hearing impairment who were referred before the age of six months for audiological evaluation and treatment from 31 per cent to 74 per cent.
Following the publication of this finding in The Lancet, a universal newborn screening service was introduced across the UK and, as of this year, is available in every UK district. The justification for this screening is that early detection would be followed by benefits to the child's acquisition of language but hitherto the evidence to support this assumption has been weak and inconclusive.
The same team at the University of Southampton, with funding from the Wellcome Trust, has now assessed expressive and receptive language skills of primary school age children, including those that were involved in the previous study on universal newborn screening.
'Receptive language' is the ability to understand communication through gestures, facial expressions and words, while 'expressive language' is the ability to express needs with the use of gestures, vocalisation, facial expressions and words. Other characteristics of the hearing impaired child and family, including the severity of the hearing impairment, the non-verbal ability of the child and the education of the mother, were also taken into account.
Those children in the study whose hearing problems were identified by the time they were nine months of age had significantly better receptive and expressive language skills than those whose problems were confirmed later. Children who were screened as newborns had higher scores for receptive language ability than those who were not screened. However, in contrast to the higher language scores observed among children whose hearing impairment was confirmed early, measures of speech did not differ significantly between groups.
Dr Kennedy, Reader in Child Health at Southampton, said: "Our study extends findings from previous studies of the relationship between early identification of hearing impairment and later outcomes. Until now it has not been certain whether universal screening of newborn babies for hearing impairment and the confirmation of hearing impairment by nine months of age has any effect on the child's subsequent verbal abilities.
"Screening and early confirmation of permanent childhood hearing impairment clearly do have clinically important benefits to the language abilities of children at primary school age. However a longer follow-up with these children is needed to establish whether at secondary school age they continue to show superior language skills and have higher academic achievement," he continued.
This new study therefore vindicates the decision to introduce universal newborn screening in the UK. It also provides indirect support for the idea that there is a 'sensitive period' during infancy when exposure to the sounds of language is particularly important for the brain development that underlies the subsequent acquisition of language.
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Notes for editors
- 'Language ability after early detection of permanent childhood hearing impairment' is published in the New England Journal of Medicine on 18 May 2006. The study was led by Dr Colin Kennedy of the University of Southampton. The study involved the Departments of Child Health, Southampton RDSU, Public Health Sciences and Medical Statistics and Psychology, University of Southampton (Dr Donna McCann, Dr Mark Mullee, Sarah Worsfold, Ho Ming Yuen and Jim Stevenson); the Institute of Primary Care and General Practice, University of Sheffield (Professor Mike Campbell); the Institute of Child Health, University College, London (Catherine Law); the National Perinatal Epidemiology Unit, University of Oxford (Stavros Petrou); and the Department of Audiology, Whips Cross University Hospital, London (Pete Watkin).
- The University of Southampton is one of the UK's top 10 research universities, with a global reputation for excellence in both teaching and research. With first-rate opportunities and facilities across a wide range of subjects in science and engineering, health, arts and humanities, the University has around 20,000 students and 5000 staff at its campuses in Southampton and Winchester. Its annual turnover is in the region of £287 million.
Southampton is recognised internationally for its leading-edge research in engineering, science, computer science and medicine, and for its strong enterprise agenda. It is home to world-leading research centres, including the National Oceanography Centre, Southampton; the Institute of Sound and Vibration Research; the Optoelectronics Research Centre; the Textile Conservation Centre; the Centre for the Developmental Origins of Health and Disease; and the Mountbatten Centre for International Studies.
- The Wellcome Trust is the most diverse biomedical research charity in the world, spending about £450 million every year both in the UK and internationally to support and promote research that will improve the health of humans and animals. The Trust was established under the will of Sir Henry Wellcome, and is funded from a private endowment, which is managed with long-term stability and growth in mind.