I am playing a bit with the fire here by starting my blog on boring terminology discussion! But I think it's very important for a constructive discussion to be clear on terminology.
I dont want to use the word "stuttering" or "stammering" to describe the disorder, because
a) stuttering is used both to label the symptom of the disorder and the disorder itself.
b) not all people who stutter have PDS. In fact, everyone has probably stuttered at some point in his/her life!
c) There are at least two classes of disorders that have stuttering as symptom, but it is not PDS. In the first disorder, people (typically over 60) might suddenly start stuttering due to brain damage to specific brain areas e.g. from a stroke. It's called neurogenic stuttering (I think). And the other class is childhood stuttering, where children start stuttering but most of them (more than 60%, probably 80%) recover.
d) There are even some who have PDS who dont stutter!!! Often called covert stuttering, they stutter very rarely, also by substituting difficult words and avoiding many speaking situations, but might still be severely impaired in social interactions.
d) I dont get confused anymore on whether I should write stuttering (US) or stammering (UK), as I am mainly in contact with British people due to my involvement with the British Stammering Association (BSA), and its research committee. :-)
Finally, using Persistent Development Stuttering (PDS) sends a clear signal that the disorder is NOT just about speech, it happens inside the brain. Speech disfluency is only the main symptom of the disorder.