COLUMBIA, Mo. (AP) — In the middle of a circle of veterans, Dave Dunklee slowly pronounced the vowels of "Mississippi." With each vowel, he strummed the guitar, creating a rhythm for the beginners in the room.

The 14 veterans around him started following his lead carefully. Once they were all in sync, they all started playing "Johnny B. Goode," in honor of Chuck Berry, and smiles grew on every face.

One ear-to-ear grin belonged to Barry Jordan, a noncombat veteran diagnosed with post-traumatic stress disorder. Before the music lesson, Jordan cried while talking about his struggle to readjust t...