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 -
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).
Parkinsonism
Major depression
Negative symptoms are still persisting
He is reacting to external stimuli