Postrecovery cognitive decline in adults with traumatic brain injury

Abstract

Objective: To assess prospectively the degree of postrecovery long-term cognitive decline after moderate to severe traumatic brain injury (TBI).

Design: Observational cohort.

Setting: Inpatient rehabilitation hospital.

Participants: Adults (N=33) with moderate and severe TBI from a well characterized sample with low attrition.

Interventions: Not applicable.

Main outcome measures: Recovery of functioning was ascertained through repeat neuropsychological assessments over the first 5 years postinjury. Cognitive decline from a baseline of 12 months postinjury to a follow-up evaluation conducted on average +/- SD 2.1+/-0.99 years later. Change was calculated using the reliable change index (RCI) for 12 neuropsychological tests commonly used in the assessment of TBI.

Results: At the group level, negligible changes in cognitive function were observed over time. However, application of the RCI using 90% confidence intervals showed statistically significant cognitive decline on at least 2 neuropsychological measures in 27.3% of study participants. Decline was most commonly observed on a test of verbal fluency and the delayed recall portion of a test of verbal list learning (Rey Auditory Verbal Learning Test), although substantial variability existed across patients. Decline was significantly correlated with hours of therapy received at 5 months postinjury (P<.02).

Conclusions: Consistent with a small number of previous studies, cognitive deterioration may follow an initial period of recovery. Overall, the pattern of decline across tests varied across individuals. Possible mechanisms of decline are discussed. Further research is needed to understand the stability of this finding and its functional implications.