Diversity in clinical trials needs work

On May 11, Rep. Lisa Blunt Rochester, Democrat of Delaware, introduced H.R.3035, "to amend the Public Health Service Act to improve the diversity of participants in research on Alzheimer's disease, and for other purposes."  The bill has 23 cosponsors, five Republican and 18 Democrats.  On introduction, the bill was promptly endorsed by the Alzheimer's Association.

I don't know if this is too blunt of an instrument, but initiative is required to improve the diversity of test subjects in Alzheimer's research.  It's well established that African Americans and Hispanics develop Alzheimer's disease at significantly higher rates that Americans of European ancestry, but test subjects in drug trials and other studies have been far too heavily weighted with people like me -- of European ancestry.

There are several reasons why it's important to improve the diversity of the pool of study participants.  The one most troubling to me is that different "flavors" of the disease manifest themselves differently in different populations.  For example, the gene most commonly identified as a risk factor for Alzheimer's disease is the APOE4 gene.  (We discussed this gene and its protein in Beating the Dementia Monster.)  That's an important factor for us of European ancestry where it's been studied, but it's not at all clear that the association is the same in minority populations ... or if the character of the disease is identical in different populations.  I did see one study (which I've lost track of) that found the APOE4 gene to be a significantly lesser factor in development of Alzheimer's disease among African Americans.

While Alzheimer's disease is more prevalent among African Americans, it's actually rare in the population of Nigeria.  But at the same time, Nigerians have the highest observed frequency of APOE4 in the world.  What's going on there?  And does it have any relevance to people of African ancestry living in Europe and the Americas?  This points to more weaknesses in our understanding of the disease, and it merits study focusing on how it manifests in diverse populations.  

So we should remember that the disease sometimes unfolds differently depending on how it appears to have begun.  Some studies associate development of Alzheimer's disease with poor lifestyle choices, especially when young -- poor diet, smoking, lack of exercise, etc.  Then, as we discussed in Beating the Dementia Monster, there are three genes primarily associated with development of young onset Alzheimer's disease and can be considered to cause it outright.  Some studies find distinct differences in how rapidly the disease advances and other characteristics that appear to hinge in part on which conditions appear to be involved in developing the disease in the first place.  My point here is that we have what I call flavors of the disease, and they work differently in different populations.

That the disease begins and unfolds differently in different populations underscores weaknesses in our understanding of the disease and we need more study.  More study means more minority participants.