Schizophrenia is characterized by positive and negative symptoms and by cognitive and affective deficits. While positive symptoms have traditionally been the focus of investigation, others and we documented neurobiological abnormalities related to negative symptoms and social-emotional deficits. Negative symptoms are a central feature of schizophrenia (American Psychiatric Association, 2013; Kirkpatrick et al., 2006), with clinical significance demonstrated by independence of other symptoms (Blanchard and Cohen, 2006, Harvey et al., 2006; Keefe et al., 2006), relation to functional impairment (Milev et al. 2005; Fenton and McGlashan, 1991; Lyne et al., 2015; Bellack et al., 1990; Mueser et al., 1990; Horan and Blanchard, 2003) and presence in neuroleptic naïve patients (Shtasel et al., 1992; Siegel et al., 2006; Lyne et al., 2015). Longitudinal studies show limited improvement with first- or second-generation antipsychotics (Murphy et al., 2006; Subotnik et al., 2015; Üçok and Ergül, 2015) or even an optimized early intervention program by a 10-year followup (Secher et al., 2015).
