This issue of the Journal of Head Trauma Rehabilitation focuses on the challenges inherent in studying the effectiveness of treatments that are experience- or learning-based. In particular, we explore the ways in which treatment theory-a theory that proposes how a particular treatment exerts its effects-can help to highlight the active ingredients of investigational treatments. Understanding the active ingredients of nonpharmacologic treatments, in turn, can inform many other aspects of treatment study design and advance the state of treatment research.

The articles published in this issue were all stimulated by the Galveston Brain Injury Conference (GBIC), which, like the articles themselves, was supported by the Moody Endowment. The annual GBIC was launched in 2000, in part, to follow up on the NIH Consensus Conference on traumatic brain injury, which had identified important gaps in research on traumatic brain injury treatment efficacy.1 Each year, the meeting organizers have selected a specific theme or topic for the conference's focus and for the 2004 conference, there was considerable interest in addressing issues related to defining rehabilitation treatments. Because of our interest and publishing in this area, Tessa Hart and I were asked to join the program committee and help plan the meeting.

In 2004, we selected specific theories that we thought were broadly relevant to rehabilitation intervention, and asked conference participants to go through the exercise of designing treatment studies in various functional areas, based on these theories. This exercise produced a rich and wide-ranging discussion, and it is safe to say that it forced group participants to confront a number of research design issues that would not have been so evident without the guidance of theory. Yet this was just an exercise, with little likelihood that these studies would actually be conducted. There was sufficient enthusiasm for the topic, however, for us to continue the theme in 2005.

In order to enhance the impact of the conference, we obtained support from the Moody Foundation to commission a set of thematic papers on this topic, and additional support was provided by the Center for Rehabilitation Sciences at the University of Texas Medical Branch. We also obtained agreement from the editors of the Journal of Head Trauma Rehabilitation to publish the resulting papers, pending peer review. We disseminated a call for proposals for these papers in the summer of 2004 and received approximately 50 applications. From these, 6 were selected, along with papers proposed and approved by Dr Hart and myself. The authors of the selected proposals and other leaders in rehabilitation research were invited to the 2005 GBIC and asked to preview the contents of their manuscripts and to engage in discussions with other conference attendees that would further shape their work. Finished manuscripts were then submitted for peer review by the journal.

Importantly, we encouraged submissions from within and outside of mainstream rehabilitation research about theories that have yet to be directly applied to rehabilitation, and about theories that are currently being tested in clinical trials. The focus of this issue and the articles contained in it is not on the empirical results of these treatment trials. Indeed, few of the articles contain any results at all. Rather, the emphasis was on designing treatment interventions with theory in mind-whether that theory is one about neuroplasticity or human goal setting-and in how the use of theory can inform all aspects of study design.

The final contents of this issue convey the breadth and heterogeneity of traumatic brain injury rehabilitation treatments. After an introductory conceptual article about treatment research (Whyte), we hear about several theories that address restoration of specific impairments in frontal executive systems (Chen et al) and explicit memory systems (Lillie and Mateer). Schmitter-Edgecombe addresses theories of implicit memory as they may pertain to compensatory training strategies. Hart and Evans discuss theory at a more meta-cognitive level-the importance of structured goal setting in self-regulatory behavior and how one might test the impact of goal setting as an active ingredient of treatment. Gordon and Manchester discuss approaches to behavioral rehabilitation that highlight the relationship between client and clinician as an important active ingredient of treatment. Finally, Vanderploeg et al and Gordon et al discuss their randomized controlled trials of structured multicomponent rehabilitation treatment systems. These trials highlight the challenge of implementing theory-based treatment concepts in real-world treatment environments. The final article in the issue, by Gonzalez-Rothi, was not one of the original proposals. Rather, Dr Gonzalez-Rothi was invited to the GBIC as a discussant. She agreed to provide a synthesis about the larger problem of advancing treatment research, stimulated by her participation in the conference and interaction with all of the authors.

It is our hope that this collection of articles demonstrates the challenges inherent in defining the active ingredients of nonpharmacologic rehabilitation interventions such that they can be rigorously studied, but also provides some optimism that this complex task can be achieved. We hope that the authors who participated in this issue will continue to move forward with their own treatment research. We also hope that by sharing the lessons learned along the way, they will help others in the field gather the urgently needed evidence about treatment effectiveness.

John Whyte, MD, PhD

Issue Editor, Moss Rehabilitation Research Institute and Thomas Jefferson University, Philadelphia, Pa

Tessa Hart, PhD

Issue Editor, Moss Rehabilitation Research Institute and Department of Rehabilitation Medicine, Jefferson Medical College, Philadelphia, Pa

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