It just read kind of awkwardly. This says exactly the same thing. Would this say it less awkwardly? I'm not hung up on this, but it could say, “representatives of advocacy groups for Alzheimer's and other dementias”. It just makes for a grammatically better sentence. I'm not hung up on it, as I say. If you prefer the original wording, I'll accept that.
On November 24th, 2016. See this statement in context.