Identification of separable cognitive factors in schizophrenia

One of the primary goals in the NIMH initiative to encourage development of new interventions for cognitive deficits in schizophrenia, Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS), has been to develop a reliable and valid consensus cognitive battery for use in clinical trials. Absence of such a battery has hampered standardized evaluation of new treatments and, in the case of pharmacological agents, has been an obstacle to FDA approval of medications targeting cognitive deficits in schizophrenia. A fundamental step in developing such a battery was to identify the major separable cognitive impairments in schizophrenia. As part of this effort, we evaluated the empirical evidence for cognitive performance dimensions in schizophrenia, emphasizing factor analytic studies. We concluded that seven separable cognitive factors were replicable across studies and represent fundamental dimensions of cognitive deficit in schizophrenia: Speed of Processing, Attention/Vigilance, Working Memory, Verbal Learning and Memory, Visual Learning and Memory, Reasoning and Problem Solving, and Verbal Comprehension. An eighth domain, Social Cognition, was added due to recent increased interest in this area and other evidence of its relevance for clinical trials aiming to evaluate the impact of potential cognitive enhancers on cognitive performance and functional outcome. Verbal Comprehension was not considered appropriate for a cognitive battery intended to be sensitive to cognitive change, due to its resistance to change. The remaining seven domains were recommended for inclusion in the MATRICS-NIMH consensus cognitive battery and will serve as the basic structure for that battery. These separable cognitive dimensions also have broader relevance to future research aimed at understanding the nature and structure of core cognitive deficits in schizophrenia.