Negative Symptoms and Cognitive Impairments in Schizophrenia: Two Key Symptoms Negatively Influencing Social Functioning.

Schizophrenia is a chronic, disabling disorder, which commonly emerges in adolescence and young adulthood. While pharmacological treatment with currently available second-generation antipsychotics exerts beneficial effects on the positive symptoms of schizophrenia, they have little effect on negative symptoms or cognitive deficits. Because these two types of symptoms are enduring, and negatively impact social functioning throughout the course of the illness, there is an urgent requirement to develop new effective therapeutic approaches to manage them. Negative symptoms have proven difficult to assess accurately because of their complexity, even with commonly used clinical rating scales such as the Scales for Assessment of Negative Symptoms (SANS). In this context, new "next-generation" assessment tools have recently been developed, which include items representing the five domains encompassed by the two established clusters of negative symptoms (diminished expression and avolition), and enable the detection of changes in severity. Despite various therapeutic approaches to alleviating negative symptoms, there are currently no established methods available for clinical practice. Cognitive deficits are also a core feature in the majority of people with schizophrenia, with impaired performance observed across many cognitive domains, including verbal memory, working memory, attention, and executive functions. Such cognitive deficits are likely associated with either reduced or inefficient function of related distributed neural networks. Psychosocial treatments for cognitive impairments in schizophrenia seem promising given the beneficial effects of cognitive remediation therapy on such impairments, as well as on social functioning, as substantiated in several meta-analytic studies with modest effect sizes. Furthermore, using functional neuroimaging techniques, the size of these therapy-induced beneficial changes in neurocognitive performance has been demonstrated to be correlated with the degree of the changes in brain activation during performing some cognitive tasks in the prefrontal and temporal cortices. This suggests neurobiological effects are exerted by psychosocial cognitive remediation treatments.