Episodes of time-limited acute psychosis, with full recovery in between, are categorized as acute polymorphic psychotic or brief psychotic disorders. Leonhard described the three forms of cycloid psychosis (CP). Perry considers it a separate entity.

We report the case of a 54-year-old male, with a 9-year history of brief psychotic disorders. He was admitted to an inpatient unit after a 4-day episode of persecutory delusion, leading to high emotional repercussions and isolation at home. Euthymia was present. Previous admissions, 9 and 5 years before, presented similar clinical pictures. Treatment with low dose paliperidone during 6-month periods had led to the complete resolution of the episodes (restitutio ad integrum: no psychotic manifestations and the ability to run his business). In this episode, 8 days after the reintroduction of 12 mg of paliperidone per day, cessation of the symptoms took place. Careful reconstruction of the clinical history showed no stressors or drug consumption. And immediately previous 5-day phase of insomnia, hyperactivity and expenditure was described by the patient's wife.

Three inpatient admissions, a careful clinical history and a thorough review of the evidence regarding Perris criteria led to a diagnosis of CP.

CP, a classical nosological approach, is helpful in a clinical setting, as it might imply different prognosis and treatment. Recognition of CP, not included as an entity by the major diagnostic systems, requires a high index of suspicion.

The authors have not supplied their declaration of competing interest.