Effects of selective serotonin reuptake and dual serotonergic–noradrenergic reuptake treatments on memory and mental processing speed in patients with major depressive disorder Ixchel Herrera-Guzmán a,b,c, * , Esteve Gudayol-Ferré a,b,c , Daniel Herrera-Guzmán d , Joan Guàrdia-Olmos e , Erika Hinojosa-Calvo b , Jorge E. Herrera-Abarca a,c a Clínica de Enfermedades Crónicas y Procedimientos Especiales CECYPE, Morelia, Mich., Mexico b Facultad de Psicología Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich., Mexico c Escuela Superior de Medicina, Sección de Estudios de Postgrado e Investigación, Instituto Politécnico Nacional, I.P.N. Mexico City, Mexico d Centro Michoacano de Salud Mental. Secretaría de Salud. Morelia, Mich., Mexico e Departament de Metodologia, Facutat de Psicologia, Universitat de Barcelona, Barcelona, Spain article info Article history: Received 11 September 2008 Received in revised form 23 October 2008 Accepted 28 October 2008 Keywords: Major depressive disorder Neuropsychology Selective serotonin reuptake inhibitor Serotonin noradrenalin reuptake inhibitor Neuropsychological assessment abstract Patients with major depressive disorder (MDD) usually suffer from altered cognitive functions of episodic memory, working memory, mental processing speed and motor response. Diverse studies suggest that different antidepressant agents may improve cognitive functions in patients with MDD. The aim of this work is to study the effects of serotonergic reuptake inhibitors (SSRIs) and serotonergic–noradrenergic reuptake inhibitors (SNRIs) treatments to improve the performance on memory tasks and mental pro- cessing speed in MDD. Seventy-three subjects meeting criteria for major depressive disorder were assessed with the Hamilton depression rating scale and a neuropsychological battery. The subjects were medicated with escitalopram (n = 36) or duloxetine (n = 37) for 24 weeks. At the end of the trial, the sub- jects were assessed again with the same neuropsychological battery used prior to the treatment. Both treatments improved importantly the episodic memory and to a lesser extent, working memory, mental processing speed and motor performance. Our results suggest that cognition is partially independent from improvement in clinical symptoms. Both groups achieved remission rates in the HAM-D-17 after 24 weeks of treatment, but SNRI was superior to SSRI at improving episodic and working memory. Our work indicates that the superiority of SNRI over the SSRI at episodic memory improvement is clinically relevant. Ó 2008 Published by Elsevier Ltd. 1. Introduction Patients with major depressive disorder (MDD) usually present alterations in various cognitive functions (Rogers et al., 2004; Aus- tin et al., 2001). Neuropsychological deficits in depressed patients may be detected in attention (Porter et al., 2003; Weiland-Fielder et al., 2004), mental processing speed, and motor performance (So- bin and Sackeim, 1997; Gualtieri et al., 2006), memory (Airaksinen et al., 2004; Austin et al., 2001), working memory (Harvey et al., 2004), and executive functions (Rogers et al., 2004; Gualtieri et al., 2006). Other recent studies suggest that MDD may cause mood depending bias in information processing, abnormal re- sponses to negative feedback, and alterations in decision taking (Chamberlain and Sahakian, 2004). The impact of cognitive altera- tions in the patient’s life functioning with MDD has been poorly studied, in spite of a recent report by Jaeger et al. (2006) suggesting that, for at least some depressed patients, the presence of neuro- psychological alterations considerably hinders their functional recovery and that the presence of motor and memory dysfunctions may predict a bad recovery of life functioning. There is also interest in the effects of antidepressant treatments on cognitive functions of depressed patients. It has been demon- strated that antidepressant agents increase the synaptic levels of one or more monoamines (Millan, 2004), and monoaminergic pathways play a crucial role in modulation of affection and cognition (Millan, 2004; Chamberlain et al., 2006). Therefore, antidepressant agents could ameliorate cognitive symptoms of depression such as memory and mental processing deficits. This hypothesis, however, has not been extensively studied. There are some reports describing an improvement in memory and attention skills in a large sample of depressed patients treated with selective 0022-3956/$34.00 Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.jpsychires.2008.10.015 * Corresponding author. Present address: Facultad de Psicología Universidad Michoacana de San Nicolás de Hidalgo, Francisco Villa 450, C.P. 58120, Morelia, Mich., México. Tel.: +443 3129913; tel./fax: +443 3129909. E-mail address: iherrera@zeus.umich.mx (I. Herrera-Guzmán). Journal of Psychiatric Research 43 (2009) 855–863 Contents lists available at ScienceDirect Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/jpsychires