<prompt> A patient of schizophrenia on neuroleptics, his psychotic symptoms get relieved but developed sadness, talks less to others, remain on the bed, all of following are likely causes except -ParkinsonismMajor depressionNegative symptoms are still persistingHe is reacting to external stimuli  <response>: In post-schizophrenic depression, the depressive symptoms become florid as an outcome of schizophrenic illness and not as a reaction to it. Schizophrenia resolves to a great extent but some symptoms still persist. For diagnosis, there should be a positive history of schizophrenia within the previous year. If schizophrenic symptoms are not present, a depressive episode is to be considered.Differential diagnosis of post-schizophrenic depression includes residual phase negative symptoms of schizophrenia, Schizoaffective disorder Depressive type, adverse effects of antipsychotics Parkinsonism, akathisia. 