A patient of Schizophrenia was staed on neuroleptics, his psychotic symptoms began to improve however he developed sadness, would talks less to others, would mostly remain to bed. This presentation could be caused by all of following except:

This question is basically asking for the differential diagnosis of symptoms of ' sadness of mood, talking less and staying on the bed" in a patient of schizophrenia who has been staed on antipsychotics. 1. The sadness of mood and decreased interaction can be of course due to depression 2. Negative symptoms of schizophrenia have a similar presentation where avolition can result in 'staying on the bed' and asociality and alogia may result in decrease interaction 3. Fuher, the use of antipsychotics can cause drug-induced parkinsonism which again looks quite similar to negative symptoms. The fouh option 'responding to external stimuli' doesn't explain the symptoms and hence is the answer