The components of executive functioning in traumatic brain injury.

Theorists have proposed models of executive functioning, and functional neuroimaging and factor analytic studies have attempted to examine the components of executive functioning. These studies have arrived at different conclusions and many empirical studies are wrought with methodological confounds. The purpose of this exploratory study was to investigate the subcomponents of executive abilities while addressing some of the limitations common in previous studies. Neuropsychological test data were obtained from a sample of individuals with a history of TBI seen at one-year follow-up (n=104). Principal components factor analysis was conducted and yielded three factors that accounted for 52.7% of the variance. The first factor included higher-order executive functions with two components: self-generative behavior and cognitive flexibility/set shifting. The second factor appeared to represent mental control, particularly of ongoing working memory. The third factor consisted of memory errors, representing failure to inhibit reporting of inaccurate information. Although the results are not entirely consistent with any of the current theoretical models of executive function, they appear to be most consistent with the 1986 model of Stuss and Benson.