Review A meta-analysis of cognitive deficits in first-episode Major Depressive Disorder Rico S.C. Lee a, b, ⁎, Daniel F. Hermens b , Melanie A. Porter a , M. Antoinette Redoblado-Hodge c a Department of Psychology, Macquarie University, NSW, Australia b Clinical Research Unit, Brain and Mind Research Institute, University of Sydney, NSW, Australia c Child Development Unit, The Children's Hospital at Westmead, NSW, Australia article info abstract Article history: Received 16 June 2011 Received in revised form 18 October 2011 Accepted 18 October 2011 Available online 15 November 2011 Background: Recurrent-episode Major Depressive Disorder (MDD) is associated with a number of neuropsychological deficits. To date, less is known about whether these are present in the first- episode. The current aim was to systematically evaluate the literature on first-episode MDD to determine whether cognition may be a feasible target for early identification and intervention. Methods: Electronic database searches were conducted to examine neuropsychological studies in adults (mean age greater than 18 years old) with a first-episode of MDD. Effect sizes were pooled by cognitive domain. Using meta-regression techniques, demographic and clinical factors poten- tially influencing heterogeneity of neuropsychological outcome were also investigated. Results: The 15 independent samples reviewed yielded data for 644 patients with a mean age of 39.36 years (SD=10.21). Significant cognitive deficits were identified (small to medium effect sizes) for psychomotor speed, attention, visual learning and memory, and all aspects of executive functioning. Symptom remission, inpatient status, antidepressant use, age and educational attainment, each significantly contributed to heterogeneity in effect sizes in at least one cognitive domain. Limitations: Reviewed studies were limited by small sample sizes and often did not report impor- tant demographic and clinical characteristics of patients. Conclusions: The current meta-analysis was the first to systematically demonstrate reduced neu- ropsychological functioning in first-episode MDD. Psychomotor speed and memory functioning were associated with clinical state, whereas attention and executive functioning were more like- ly trait-markers. Demographic factors were also associated with heterogeneity across studies. Overall, cognitive deficits appear to be feasible early markers and targets for early intervention in MDD. © 2011 Elsevier B.V. All rights reserved. Keywords: Neuropsychology Cognitive impairment First-episode Major Depressive Disorder Depression Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 1.1. Early identification and intervention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 1.2. Cognitive functioning in Major Depressive Disorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 2. Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 2.1. Search criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 2.2. Statistical analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Journal of Affective Disorders 140 (2012) 113–124 ⁎ Corresponding author at: Clinical Research Unit, Brain and Mind Research Institute, 100 Mallett St, Camperdown, NSW 2050, Australia. Tel.: +61 2 9351 0763. E-mail address: sze.lee@sydney.edu.au (R.S.C. Lee). 0165-0327/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2011.10.023 Contents lists available at SciVerse ScienceDirect Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad