Summary
Childhood disintegrative disorder (cdd), early onset schizophrenia (eos), and late onset autism (loa) often follow a similar course: initially, development is normal, then there is a sudden  neuropsychiatric deterioration of social interaction and communication skills, which is combined with a decline in intelligence and reduction in daily activities. A 9-year-old boy was admitted to the paediatric ward with acute onset of secondary epileptic seizures. It was not long until the boy’s symptoms resembled that of patients with cdd, eos and loa. Intensive tests led to the diagnosis of anti-nmda-receptor encephalitis. Anti-nmda-receptor encephalitis should be regarded as a possible organic cause underlying the syndromal presentation of cdd, eos and loa.