<prompt> Ramu, a 22 year old single unmarried man is suffering from sudden onset of 3rd person hallucination for the past 2 weeks. He is suspicious of his family members and had decreased sleep and appetite. The diagnosis is:SchizophreniaAcute PsychosisAcute maniaAcute delirium  <response>: B i.e. Acute psychosis As you know 3rd person hallucination are very much characteristic of schizophrenia; but for making a diagnosis of schizophrenia, atleast 6 months duration is required. So this cant be schizophrenia. The consciousness orientation recognizes family members is normal, so acute delirium is ruled out. Now if we concentrate upon symptoms- 3rd person hallucination is a characteristic feature of schizophrenia; but decreased appetite sleep are not the essential criteria of mania essential criteria is persistently abnormally elated mood. Last but not the least you should know that diagnostic criteria of schizophrenia, schizophreniform disorder, acute psychosis delusional, brief psychotic disorder are same only differentiation is duration of symptoms In Brief psychotic disorder 1 monthQ duration of disturbance In Acute delusional psychosis 3 monthsQ In Schizophreniform disorder 6 months 1 duration of disorder In Schizophrenia 6 monthsQ 