Plateauing (a complete lack of progress or stasis) or regression (loss of previously acquired skills) of developmental abilities should raise serious concerns and lead to a referral for a detailed assessment, a medical opinion and appropriate investigations.
Conditions that may present with developmental regression
- Epileptic encephalopathy
- Rett syndrome
- Childhood disintegrative disorder
- Degenerative neurological disorders
About 1/3rd of children with autism have a history of regression; the onset of regression is during the first three years, features of autism are also present and there is no loss of motor skills.
Later onset of regression (after the age of 3 years), associated loss of bowel and bladder control and behaviour symptoms of distress and hyperactivity are indicative of a rare condition – childhood disintegrative disorder.
Epileptic encephalopathies are rare but remain a clinical concern if there is a history of regression of developmental skills. Epileptic encephalopathy appearing before the age of two years is often associated with ataxia. Medical opinion should be sought if there are physical signs or a history suggestive of seizures or epilepsy. Children with autism and regression also have a higher chance of developing epilepsy.
Epilepsy is a relatively common condition in children affecting about 1in 200 children. Usually, it has no severe impact on children’s development. Landau–Kleffner syndrome is a very rare type of epileptic encephalopathy that appears after the age of 3 years. It appears after a period of normal development with severe language loss and, sometimes, with hyperactivity, loss of social skills and behaviour problems. The child may not have overt epilepsy. Only an abnormal EEG, particularly during sleep, may confirm the diagnosis. See here for further information.
Continuing severe progressive regression of all skills and abilities with profound motor changes is seen in some rare degenerative neurological conditions.
For related information see: Differential diagnosis and coexisting conditions