revision

You don't want to say 'stresses out'. That is a term that means you have too much stress in your life. 'Stresses' means emphasizes, which is what you want to say here.

This can be made simpler.

Ponterotto stresses the fact that participants sixty-five years of age and older are more vulnerable to misinterpretations and miscommunications.

I think that says the same thing you wrote. I'm only a year shy of sixty five, and I might have misinterpreted it.

Lewis has been making me smile today with his comments.  He's made me think, though, about how you have worded this sentence.  It sounds like Ponterotto has stated that when one turns 65, he suddenly becomes more vulnerable to misinterpretation and miscommunication.  I don't know Mr. Ponterotto and haven't read his works, but is he really stating (and stressing) that as a fact?  I'll venture a guess that a study (or more than one) shows that people in the age group of 65 and older are more likely to be vulnerable.  That is a different meaning from how I interpret your sentence.  (I'm not 65, but I am old enough to be Lewis's (much) younger sister.)  When paraphrasing, it is important to keep the same meaning.