Neurocognition and neuroimaging of persistent negative symptoms of schizophrenia

Negative symptoms have been a conundrum to researchers and clinicians alike since having first been identified by Bleuler and Kraepelin. The term 'negative symptoms' has been scrutinized with regards to what it encompasses. Negative symptomatology has been categorized into distinct subdomains, including primary symptoms, secondary symptoms, deficit syndrome and, more recently, persistent negative symptoms (PNS). Although there have been some theories put forward with regards to negative symptoms, there are still discordant findings regarding PNS. Thus, this article aimed to review the structural, functional and cognitive correlates of PNS in an attempt to better understand these specific negative symptoms in schizophrenia. According to the reviewed literature, deficit syndrome appears to have similar neurocognitive and structural deficits as PNS; however, some minor distinctions may suggest that PNS are a separate subtype of negative symptoms. White matter decrements in the frontal lobe and gray matter reductions in the temporal lobe may be related more specifically to PNS. Furthermore, unlike deficit syndrome, structural abnormalities in the frontal and temporal lobe also appear to be related to PNS in patients with first-episode schizophrenia. Cognitive domains, such as memory, are impaired and appear to be predominantly related to PNS. Hence, PNS do appear to have neuroimaging and neurocognitive correlates and warrant further research.