Unfortunately, these problems can occur at any age. In the absence of a genetic reason for the speech problem or onset of neurodegenerative disease, there could be other more common reasons. When confronted with this problem in CFS and Fibromyalgia patients, we found that chronic central nervous system infections were present that could explain the problem. Such infections often go along with short-term memory loss, so-called brain fog, intermitent confusion, depression, fatigue and other other symptoms.
I would try to assess whether this is only a speech problem, or whether the speech problem is just one of many other problems not expressed in your question.
Prof. Garth Nicolson
I am intrigued by your post. Back in November 2010 I experienced the same thing. I'm 21 years old and prior to november I was a fluent speaker. But gradually my speech became labored and I had rapid onset of stuttering. The hospital diagnosed me with a speech disorder called dysarthria however they have not been able to find a reason for my rapid onset speech disorder. All of my MRI's came back normal as well. Have you found a diagnosis yet?