ABSTRACT
The importance of cognitive impairment in people with schizophrenia has been established since Emil Kraepelin’s first description of the illness as dementia praecox (Kraepelin 1919). Nowadays, cognitive deficits are considered a core feature of schizophrenia, detectable at the onset of the illness (Gopal and Variend 2005), in neuroleptic-naïve patients (Saykin et al. 1994; Hill et al. 2004), and even in the prodromal phase of the disease (Simon et al. 2007; Fusar-Poli et al. 2012), and such impairment persists with the progression of the illness (Heaton et al. 2001; Morrison et al. 2006). Almost all patients demonstrate some decline in measures of neurocognitive functioning and the global cognitive deficit in schizophrenia averages between one and two standard deviations below the mean of healthy control subjects (Green et al. 2004), with prominent impairment in psychomotor speed, attention, verbal and working memory, and executive functions (Lee and Park 2005; Dickinson et al. 2007; Knowles et al. 2010). These deficits have been demonstrated to underlie part of the functional disability associated with the disorder (Jaeger et al. 2006; Niendam et al. 2006). Several studies have also shown that cognitive deficits are related to poorer outcome in different functional domains (Bowie et al. 2006, 2008), quality of life and psychosocial rehabilitation interventions (Evans et al. 2004; Green et al. 2004; Milev et al. 2005, Raffard et al. 2009).
