by Jennifer Phillips, Ph.D.
Here’s my somewhat belated follow up to Mark’s last post regarding the unanswered questions about Vitamin A as a potential treatment for Usher syndrome. I regret that in doing so, I may be igniting another Summer Debate conflagration, but I would be remiss if I didn’t attempt some response to Mark’s complaints that the ‘scientific community’ (that’s right, Large Hadron Collider people, you’re on the hook for this too) has ‘dropped the ball’ by failing to produce research that would definitively support or reject the use of Vitamin A in Usher patients.
Mark’s main specific query is on the subject of why there have been no additional studies to clarify the original research by Berson et al. I think the answer is multifaceted, but boils down to the fact that our resources for addressing these kinds of research questions are not limitless. Studies of this magnitude (the 1993 Berson study had over 600 participants who were followed clinically for over 4 years) are expensive. Is it worth spending money to address such questions? Generally speaking, yes. However, recall that this particular study was lauded--even by its critics--for its excellent methodology. It was the strength of the conclusions that were questioned, not the study design. This raises the question, at least in my mind, that if a study of this admirable magnitude and quality could not arrive at a more convincing conclusion, how could further studies be expected to add much more?
I think it would be a hard sell to get institutional support for such a study. “Resources” doesn’t just mean money. One is also committing laboratory and clinical space, equipment and personnel to work on this research, thereby limiting the extent to which they can be used for other projects. Moreover, one is committing subjects—patients with Usher, or at least a mixed cohort of RP patients—to participate in this study rather than another. Should we be willing to expend all of these extremely valuable resources—years of people’s lives, millions of dollars—to readdress the question of vitamin A rather at the expense of studying another potentially more promising compound (like, for example, Valproic Acid, or TUDCA)? I don’t think that’s an easy choice to make, by any means.
The more general complaint that Mark shared in his previous post, though, is one of frustration with the fact that science is failing to find solutions fast enough. More than once on this blog, Mark has lamented that there aren’t more concrete answers about so many aspects of Usher syndrome. I am truly sympathetic to the frustration that such uncertainty engenders, and I fully understand that the clock is ticking here. While ‘science’ takes its sweet time pondering these pressing matters, more Usher patients and their families are coping with vision loss and other life-changing aspects of the disease. That said, and at the risk of sounding callous, if you’re looking to science to provide ‘proof’ and illuminate the ‘truth’ of any given situation, you’re thinking about science all wrong.
Science is the best way humans have ever devised to ask questions about the natural world. However, both the complexity of the questions and the completeness of the answers we obtain from this method are heavily dependent on how much we already understand. There is always more to learn; we are never finished. When you ask for proof, the best we can offer in return is evidence. What some might describe as ‘truth’, a committed scientist would qualify as ‘our most informed opinion based on the current data’.
The amount of data we have about Usher syndrome has grown exponentially in the past few decades. We are now engaged in targeted research of interventions to improve all aspects of the pathology. Thousands of people are working very hard on these questions right this minute, and in doing so we have to remain focused and specific about our goals. There are more questions to answer than we have hours in the day, and more potential lines of inquiry than we can possibly pursue in a lifetime.
Choices about what particular research to engage in, whether basic or clinical in nature, are made based on a huge array of variables. Is there enough time, space, money, and need for another study on Vitamin A? I don’t know—but I do know that if the clinical researchers actively studying Usher at the present time choose not to follow up on the original findings with another study to address the efficacy of Vitamin A on forestalling vision loss, it will NOT be due to a lack of enthusiasm for helping RP patients, or incompetence, or callous disregard for the need to provide families with satisfying answers. Rather, it will simply be due to the decision to put valuable resources, both material and human, toward what are judged to be more promising lines of inquiry.