In Down syndrome epilepsy has two peaks of onset, the first is the development of epilepsy in infancy and the second is associated with the onset of dementia.

Epilepsy in Infancy

Epileptic spasms (sometimes called infantile spasms, West Syndrome or Salaam Attacks) are uncommon epileptic seizures which can occur in infants with Down syndrome. They also occur in infants without Down syndrome, occurring in less than one in every 2000 infants. They are more likely to occur in children who have some difficulties with their development. Epileptic spasms occur in around 5% of children with Down syndrome, making them much more likely to occur than in other children.

Epileptic spasms usually occur in children aged less than 12 months. They most often start between 3 and 6 months old. Families may notice that their child’s head will suddenly nod forwards. Sometimes the arms or legs will also quickly move and their child may become upset. The movements are very brief (lasting less than a second), but may occur in “clusters” where several of these movements occur close together. These clusters may happen after the child wakes from sleep.

Epilepsy in Adulthood

Over 80% of people with Down syndrome and dementia develop seizures and this may be the presenting symptom of the dementia. There may be a change in seizure frequency, pattern or severity associated with the dementia compared with their previous epilepsy characteristics.