Dyke-Davidoff-Masson syndrome, or cerebral hemiatrophy, is a pre- or perinatally 
acquired entity characterized by predominantly neurologic symptoms, such as 
seizures, facial asymmetry, contralateral hemiplegia, and mental retardation. 
Psychiatric symptoms are rarely reported. We report the first case of left 
cerebral hemiatrophy and a late onset of treatment-resistant schizoaffective 
disorder after a stressful life event. The patient finally responded well to 
clozapine. The clinical history and results from structural neuroimaging are 
highlighted to discuss the possible developmental bias for psychotic disorders.