Developmental delay can be caused by learning disabilities, in which case the delay can usually be overcome with time and support - such as with physiotherapists, occupational therapists, and speech and language therapists. Other causes which may cause a permanent delay in development include genetic disorders such as Down syndrome and Fragile X, childhood infections such as meningitis or encephalitis, and metabolic disorders such as hypothyroidism. Metabolic disorders are more likely to cause delayed development in older children as many congenital metabolic problems which are easily managed are screened for in the neonatal period. The use of toxic substances in pregnancy, particularly alcohol, can lead to developmental delay if they affect the neurological development of the fetus, such as in fetal alcohol syndrome. Even though there are many known causes of delay, some children will never receive a diagnosis.
Investigation
Developmental delay is usually initially noticed by parents or health visitors, and will then need to be assessed in order to ascertain which milestones they are missing. The child may only be delayed in one area of development, such as gross or fine motor, or in more than one. Developmental screening can be done by a trained healthcare professional, in which they will play with the child to see how they speak, move, and respond. If this indicates a delay, the child should then be assessed with a developmental evaluation, done by a highly trained professional such as a developmental psychologist or paediatrician, or a paediatric neurologist. After a thorough history and examination, including the developmental assessment, 1/3 of cases can be diagnosed. If the diagnosis is unclear, or for confirmation, further tests can be done.
Chromosome microarray and karyotyping to look for trisomy, microdeletions, and duplications. It is the most sensitive diagnostic test available and is used first line in all cases, but can miss balanced translocations and low-level mosaicism.
Specific gene testing is available for certain disorders such as Rett syndrome, although these are expensive tests which aren't widely available
Selective metabolic investigations may be useful in the absence of other identifiable causes, and the specific tests done will depend on the presentation. Inborn errors of metabolism causing metabolic disorders are rare and there are limited treatment options even if they are successfully diagnosed.
Neonatal screening is used in the UK and can diagnose certain inborn errors of metabolism before they cause significant developmental problems, with the aim to manage them so that no permanent damage occurs.
Canada, the USA, and the Netherlands offer more extensive newborn screening, encompassing some other amino acid, organic, and urea cycle disorders
Management
The specific management of children with global developmental delay will depend on their individual needs and underlying diagnosis. Early intervention is essential to support the child to reach their full potential. Specialists involved in the management of GDD in children include
As well as involving professionals, parents can support the development of their child by playing with them, reading with them, showing them how to do tasks, and supporting them to participate in activities of daily living such as washing, dressing, and eating.
