Original article
Postrecovery Cognitive Decline in Adults With Traumatic Brain Injury

https://doi.org/10.1016/j.apmr.2008.07.004Get rights and content

Abstract

Till C, Colella B, Verwegen J, Green RE. Postrecovery cognitive decline in adults with traumatic brain injury.

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.

Section snippets

Participants

The study sample comprised 33 patients with moderate to severe TBI. All participants were part of a larger, longitudinal study on cognitive and motor recovery that was undertaken in the inpatient neurorehabilitation program at the Toronto Rehabilitation Institute.

This study was approved by the Research Ethics Board of the Toronto Rehabilitation Institute.

Participants in the larger study underwent neuropsychological testing at 2, 5, and 12 months postinjury and met the following inclusion

Group Data

Descriptive statistics for the standardized neuropsychological measures for the TBI sample are displayed in table 2. Means at the 12-month baseline and follow-up assessments fell within the normative range across all tests. The only statistically significant change across time, after adjusting for multiple comparisons, was an improvement on the TMT Part A (t30=3.50, P=.001). The magnitude of change was one half an SD, and showed a medium effect size. Cohen d45effect size differences for all

Discussion

In some settings, there is a tacit assumption that cognitive gains made over the early recovery period are maintained into the long-term or may even increase. However, using the RCI, we showed that 27% of our sample (9 of 33) manifested cognitive decline on at least 2 subtests (of a 12 subtest neuropsychological battery) between a 12-month baseline evaluation and a follow-up evaluation conducted 1 to 4 years later. Although most individuals in the current study remained stable or showed ongoing

Conclusions

The results of this study suggest that postrecovery decline does occur in a considerable proportion of individuals with moderate to severe TBI and may affect an array of cognitive functions. These findings are important clinically because they demonstrate that a normalized early recovery does not necessarily predict maintenance of recovery, let alone continued recovery. Our findings also provide some clues about the risk factors that may contribute to late decline. The strongest correlate of

Acknowledgments

The authors wish to thank Leslie Miller, MA, for her assistance with patient testing and Kadeen Johns, BA, for her ongoing administrative support. The authors acknowledge the support of Toronto Rehabilitation Institute who receives funding under the Provincial Rehabilitation Research Program from the Ministry of Health and Long-Term Care in Ontario. The views expressed do not necessarily reflect those of the Ministry.

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  • Cited by (0)

    Supported by the Canadian Institutes of Health Research (grant no. MOP-67072), Physicians' Services Incorporated (grant no. 05-50), and the Ontario Mental Health Foundation.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

    Reprints not available from the author.

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