Developing concepts in negative symptoms: primary vs secondary and apathy vs expression.

Negative symptoms in schizophrenia, such as blunted affect, alogia, asociality, anhedonia, and avolition, remain challenging to treat in many patients, but new concepts may lead to a better understanding of the definition and treatment of these symptoms. The most widely used rating scales for negative symptoms (the Scale for the Assessment of Negative Symptoms and the Positive and Negative Syndrome Scale) were developed in the 1980s, but more recent findings, such as insight into aspects of anhedonia, have led to the creation of new rating scales (the Clinical Assessment Interview for Negative Symptoms and the Brief Negative Symptom Scale). Clinicians should differentiate between primary and secondary negative symptoms in order to select the best treatment option. Secondary negative symptoms may be caused by comorbid conditions, psychotic symptoms, medication side effects, and substance abuse. On most rating scales, negative symptoms have also been found to load onto 1 of 2 domains, apathy/anhedonia/asociality or diminished expression (blunted affect and alogia). This distinction may facilitate the development of new treatments.