<prompt> A 70 yr old man presents with ho prosopagnosia, loss of memory, 3rd person hallucination since 1 month. On examination deep Tendon reflexes are increased, the mini-mental examination score is 2030. What is most likely diagnosis -Dissociated dementiaSchizophreniaAlzheimers diseasePsychotic disorder  <response>: Similar to previous question a low MMSE score suggests cognitive impairment, e.g. Dementia.Prosopagnosia, loss of memory and low MMSE score suggest the diagnosis of Alzheimers disease.Only confusion in this question is third person hallucination. Third person hallucination is characteristic of schizophrenia. However, schizophrenia can be excluded, because the MMSE score is not low in schizophrenia. 