Consolidation deficits in traumatic brain injury: The core and residual verbal memory defect

Abstract

While memory deficits are consistently found to be a salient problem in individuals with moderate to severe traumatic brain injury (TBI), the specific memory processes (i.e., encoding, consolidation, and retrieval) underlying the verbal memory deficit are disputed in the literature. The current study evaluated the recovery of these verbal memory processes over time. A TBI patient group evaluated acutely after the injury (baseline) and again at 6 months and 1 year post injury was compared to a demographically similar control group evaluated only once. The current results replicated previous findings in support of an impaired consolidation hypothesis as the primary deficit underlying memory impairment in TBI. These deficits are reflected in relatively more rapid forgetting through 1 year post injury and relatively less proactive interference up to 6 months post injury.

Keywords:

• Traumatic brain injury
• Memory
• Neuropsychological tests
• Closed head injury
• Longitudinal studies
• Veterans health.

The views expressed herein are those of the authors and do not necessarily reflect the views or the official policy of the Department of Veterans Affairs, Department of the Army, or U.S. Government. No author has any financial or other conflicts of interest that might bias this work. The authors are grateful to Dean C. Delis and Joel H. Kramer for their comments and suggestions on earlier versions of this manuscript.

The research reported here was supported by the Department of Veterans Affairs, Veterans Health Administration (VHA), and the Defense and Veterans Brain Injury Center (DVBIC) through the U.S. Army Medical Research and Materiel Command under Contract No. W81XWH-09-C-0026. Further support was provided by the James A. Haley Veterans’ Hospital.

Notes

¹ An analysis was also conducted using long-delay free recall versus the discriminability index with both measures converted to standard scores. The results did not differ from the aforementioned analysis.

² These reliability coefficients are from the CVLT–II Manual (Delis et al., 2000), because they are not reported in the original CVLT manual (Delis et al., 1987).