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Primary and persistent negative symptoms: Concepts, assessments and neurobiological bases
Primary and persistent negative symptoms (PPNS) represent an unmet need in the care of people with schizophrenia. They have an unfavourable impact on real-life functioning and do not respond to available treatments. Underlying etiopathogenetic mechanisms of PPNS are still unknown. The presence of primary and enduring negative symptoms characterizes deficit schizophrenia (DS), proposed as a separate disease entity with respect to non-deficit schizophrenia (NDS). More recently, to reduce the heterogeneity of negative symptoms by using criteria easily applicable in the context of clinical trials, the concept of persistent negative symptoms (PNS) was developed.
Both PNS and DS constructs include enduring negative symptoms (at least 6months for PNS and 12months for DS) that do not respond to available treatments. PNS exclude secondary negative symptoms based on a cross-sectional evaluation of severity thresholds on commonly used rating scales for positive symptoms, depression and extrapyramidal side effects; the DS diagnosis, instead, excludes all potential sources of secondary negative symptoms based on a clinical longitudinal assessment.
In this paper we review the evolution of concepts and assessment modalities relevant to PPNS, data on prevalence of DS and PNS, as well as studies on clinical, neuropsychological, brain imaging electrophysiological and psychosocial functioning aspects of DS and PNS.
Keywords: Deficit schizophrenia, Persistent negative symptoms, Neuroimaging, Electrophysiology, Neurocognition, Real-life functioning.
a Department of Psychiatry, University of Naples SUN, Naples, Italy
b Department of Psychiatry, Psychotic Disorders Research Program, Istanbul Faculty of Medicine, Istanbul, Turkey
c University of Groningen, University Medical Center Groningen, Department of Neuroscience and Department of Psychology, Groningen, The Netherlands
⁎ Corresponding author at: Department of Psychiatry, Second University of Naples (SUN), L.go Madonna delle Grazie, 1, 80138 Naples, Italy.
© 2016 Elsevier B.V., All rights reserved.