How to distinguish between the neuroleptic-induced deficit syndrome, depression and disease-related negative symptoms in schizophrenia

A major challenge in the clinical assessment of schizophrenia is the differentiation between depressive features, negative symptoms and neuroleptic side effects, including the adverse subjective experiences associated with this medication, The problems include the degree of symptom overlap, and the lack of precise operational definitions, particularly for negative symptoms and the putative, neuroleptic-induced deficit syndrome. The diagnostic process is further confounded by the need to discriminate between primary negative symptoms as persistent, enduring deficits, and social and emotional withdrawal secondary to positive symptoms, or related to depressive features or drug effects such as sedation and the bradykinesia component of parkinsonism. To distinguish between these elements is likely to require careful observation of patients with schizophrenia, over time, by trained raters using appropriate rating scales for depression and negative symptoms that are sensitive to change, Ratings of patients' subjective experiences regarding mood and awareness of behavioural and cognitive deficits should also be included. The associations between the subjective data and the objective ratings of depression, negative symptoms and drug side effects may help with clinical discrimination in these areas of dysfunction and with the refinement of their phenomenological descriptions.