PDS in old age

Do older people show less symptoms of PDS or are there fewer to have PDS? I gave a talk at the Oxford Dysfluency Conference, where I showed that the attendance of therapy is declining with age. I argued that the effect is not due to the fact that fewer older people stutter, but due to other reasons: see my post. But a few people said that there is a decline in age. But I havent found any very convincing articles yet. I just looked at the internet and couldnt find anything in 5 minutes. (So it cannot exist. :-)

I also have conceptual problems to believe it as it doesnt fit in well with my understanding of PDS. If it's really a defect somewhere, then how can old age make it better? Or if there are compensationary systems, then shouldnt young people be more likely to stutter less? The only reason I can come up with is that the neurotransmitter balance is changing, which then affects the severity of PDS symptoms. So if there is clear research showing that older people stutter less, then this seems to point to a dependence on the neurotransmitter systems. Well, I guess you can also argue that people calm down and have less energy to stutter!