Processing speed mediates the relationship between verbal memory, verbal fluency, and functional outcome in chronic schizophrenia Natalia Ojeda a,b, ⁎ , Javier Peña a , Pedro Sánchez b , Edorta Elizagárate b , Jesús Ezcurra b a Department of Psychology, University of Deusto, Avda. Universidades, 24. 48007 Bilbao, Spain b Refractory Psychosis Unit, Hospital Psiquiátrico de Alava, C/ Alava, 43. 01006 Vitoria, Spain Received 4 October 2007; received in revised form 18 December 2007; accepted 20 December 2007 Available online 8 February 2008 Abstract Verbal fluency and verbal memory have been reported to be diminished in patients with schizophrenia. These deficits could partially predict functional disability in this pathology. However, processing speed often mediates the relationship among cognitive processes in the disorder. Our goal was to analyse the influence of processing speed as mediator of the relation between verbal fluency–verbal memory and functional disability in chronic schizophrenia. We examined 90 hospitalized patients and 30 healthy controls (matched for gender, age and years of education). The neuropsychological battery included tests for verbal fluency, verbal memory, motor speed and processing speed. Outcome measures included Disability Assessment Schedule (DAS-WHO) and number of hospitalizations (NH). Results confirmed chronicity on clinical symptoms (PANSS total X = 48.94 + 14.97 PANSS negative X = 27.81 + 10.18, PANSS positive X = 23.51 + 10.81) and impairment on functional disability (DAS-WHO X = 13.62 + 4.28). As expected, verbal fluency was severely impaired in patients and significantly predicted functional outcome. Immediate and Delayed Verbal Memory were also severely impaired and predicted functional outcome. However, when processing speed was entered in the regression analyses the significance of verbal fluency and verbal memory decreased significantly. Sobel's equation was significant, suggesting full mediation. Our findings suggest that processing speed may be a central factor in the relation between cognitive symptoms and functional outcome in chronic schizophrenia. © 2008 Elsevier B.V. All rights reserved. Keywords: Chronic schizophrenia; Neurocognition; Functional disability; Verbal fluency; Verbal memory; Processing speed 1. Introduction The presence of cognitive deficits in schizophrenia has been extensively reported as a core feature of the disorder (Heinrichs and Zakzanis, 1998; Wilk et al., 2005), and the average impairment can reach 2 standard deviations below normal performance (Bilder et al., 2000; Harvey and Keefe, 1997). The suggested evidence of cognition as best predictor of functional outcomes and disability in schizophrenia including work functioning and independent living (Gold et al., 2002; Hofer et al., 2005) provided further relevance to the study of these deficits, specially after the published weak relation with clinical symptoms (Green, 1996). Green additionally characterized the association between specific neurocognitive domains and different measures Available online at www.sciencedirect.com Schizophrenia Research 101 (2008) 225 – 233 www.elsevier.com/locate/schres ⁎ Corresponding author. Department of Psychology, University of Deusto, Avda. Universidades, 24, 48007 Bilbao, Spain. Tel.: +34 94 413 90 00x2671; fax: +34 94 413 90 89. E-mail address: nojeda@fice.deusto.es (N. Ojeda). 0920-9964/$ - see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2007.12.483