It is difficult to establish whether a patient has late onset schizophrenia or frontotemporal dementia. The object of the following case report is to point out the difficulty of making a differential diagnosis between these two entities.

A 49-year-old female patient was admitted to our hospital after presenting with auditory and visual hallucinations, formal thought disorder, persecutory delusions, ideas of reference, insomnia. Memory, executive function and attentional tasks were severely compromised. Computerized tomography showed incipient frontal lobe atrophy. There were no significant abnormalities found in blood and urine samples or physical and neurological examinations. After showing no response to olanzapine, and extrapyramidal side effects to fluphenazine, risperidone was initiated which subsequently led to complete withdrawal of positive symptoms.

Patients presenting with psychotic symptoms after the age of 40 presented a diagnostic quandary, as they were less likely to present with negative symptoms, formal thought disorder or affective blunting, and more likely to have systematised delusions and visual hallucinations. Frontotemporal dementia is a disorder that can present itself with cognitive decline and a large range of psychiatric symptoms. The risk of late onset schizophrenia is greater in women, possibly implicating a causative role of female sex hormones. Atypical antipsychotics risperidone and olanzapine seem to be an adequate treatment.

Schizophrenia is a heterogeneous disease with a large variety of clinical manifestations. Special care should be given to patients with age over 40, including neurocognitive assessment, laboratory and hormone tests, and a long-term follow-up.

The authors have not supplied their declaration of competing interest.