The Dodo website reports the roughness and cruelty of capturing dolphins for a life in captivity, often seperating a calf from its mother. The Dodo comments 'A cost for an entertainment dolphin can be between $28,000 and $285,000'. The Dodo comments:
'An excellent example is dolphin-assisted therapy. Some parents report that their sexually abused children were no longer suicidal, while many other families say that they did not see immediate results while starting the treatment. Yet, therapists told them to keep going back. Many claim that dolphin assisted therapy can help people enhance their motor skills and increase attention span. Needless to say, scientists have been unable to explain how the therapy exactly works. If anything, dolphin assisted therapy is extremely expensive and can increases the possibility of the animal causing an injury on the patient.'
Whilst there may be some therapeutic benefits for the humans, there is far less reason to believe that captive dolphins also benefit.
Read more at the Dodo