Heterogeneity Is a Hallmark of Traumatic Brain Injury, Not a Limitation: A New Perspective on Study Design in Rehabilitation Research

Natalie V. Covington, Melissa C. Duff

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Purpose In both basic science and intervention research in traumatic brain injury (TBI), heterogeneity in the patient population is frequently cited as a limitation and is often interpreted as a factor reducing certainty in the generalizability of research findings and as a source of conflicting findings across studies. Historically, much of TBI research in rehabilitation and cognition has relied upon case-control studies, with small to modest sample sizes. In this context, heterogeneity is indeed a significant limitation. Here, however, we argue that heterogeneity in patient profiles is a hallmark characteristic of TBI and therefore cannot be avoided or ignored. We argue that this inherent heterogeneity must be acknowledged and accounted for prior to study design. Fortunately, advances in statistical methods and computing power allow researchers to leverage heterogeneity, rather than be constrained by it. Method In this article, we review sources of heterogeneity that contribute to challenges in TBI research, highlight methodological advances in statistical analysis and in other fields with high degrees of heterogeneity (e.g., psychiatry) that may be fruitfully applied to decomposing heterogeneity in TBI, and offer an example from our research group incorporating this approach. Conclusion Only by adopting new methodological approaches can we advance the science of rehabilitation following TBI in ways that will impact clinical practice and inform decision making, allowing us to understand and respond to the range of individual differences that are a hallmark in this population.

Original languageEnglish (US)
Pages (from-to)974-985
Number of pages12
JournalAmerican journal of speech-language pathology
Issue number2S
StatePublished - Apr 16 2021

Bibliographical note

Funding Information:
Work described in this article was funded by an ASHFoundation Clinical Research Grant awarded to N. V. C. and an National Institute on Disability, Independent Living, and Rehabilitation Research Grant 90SFGE0012 awarded to M. C. D. The authors thank the attendees of the International Cognitive-Communication Disorders Conference for discussions that prompted this article.

Publisher Copyright:
© 2021, American Speech-Language-Hearing Association. All rights reserved.

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Review


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