Journal of the International Neuropsychological Society

Research Articles

The contribution of injury severity, executive and implicit functions to awareness of deficits after traumatic brain injury (TBI)

NICHOLAS MORTONa1 c1 and LYNNE BARKERa2

a1 Neurorehabilitation Services Tickhill Road Hospital, Doncaster, South Yorkshire

a2 Department of Psychology, Sheffield Hallam University, Sheffield, South Yorkshire

Abstract

Deficits in self-awareness are commonly seen after Traumatic Brain Injury (TBI) and adversely affect rehabilitative efforts, independence and quality of life (Ponsford, 2004). Awareness models predict that executive and implicit functions are important cognitive components of awareness though the putative relationship between implicit and awareness processes has not been subject to empirical investigation (Crosson et al., 1989; Ownsworth, Clare, & Morris, 2006; Toglia & Kirk, 2000). Severity of injury, also thought to be a crucial determinant of awareness outcome post-insult, is under-explored in awareness studies (Sherer, Boake, Levin, Silver, Ringholz, & Walter, 1998). The present study measured the contribution of injury severity, IQ, mood state, executive and implicit functions to awareness in head-injured patients assigned to moderate/severe head-injured groups using several awareness, executive, and implicit measures. Severe injuries resulted in greater impairments across most awareness, executive and implicit measures compared with moderate injuries, although deficits were still seen in the moderate group. Hierarchical regression results showed that severity of injury, IQ, mood state, executive and implicit functions made significant unique contributions to selective aspects of awareness. Future models of awareness should account for both implicit and executive contributions to awareness and the possibility that both are vulnerable to disruption after neuropathology. (JINS, 2010, 16, 1089–1098.)

(Received November 09 2009)

(Reviewed July 15 2010)

(Accepted July 15 2010)

Correspondence:

c1 Correspondence and reprint requests to: Nicholas Morton, Rotherham, Doncaster and South Humber Mental Health NHS Trust, Tickhill Road Hospital, Doncaster, South Yorkshire, DN4 8QL. E-mail: n.morton@nhs.net