I don't think so. It could be purely because of this part of the text:

This is because they haven't really picked up the accent. Their speech patterns have changed. Injury to their brain causes them to lengthen syllables, alter their pitch or mispronounce sounds. These changes make it sound like they have picked up an accent. They may lengthen syllables.

wow, that's really interesting. I wonder if linguistic theorists would be interested in that. I don't know enough about it (linguistic theory), but it's just a thought.

Imagine a Swedish person with a stroke ending up with an African-American accent...

Sounds like a definite case of past-life intrusion to me... However, it's also possible that it simply was an accent she was fond of, and her mind simply found that to be the easiest one to speak after the stroke...who knows? Strange phenomenon....thanks for the find! I'm still leaning more towards some past life interference here...