For more than a decade, the former heavyweight champion has suffered from the disease that slowed his reflexes and made it difficult for him to talk. Ali had received five days of treatments at the clinic before deciding to quit.

Ali criticized Jerry Jacobson, a retired dentist and oral surgeon with whom Ali began treatments July 28, for not respecting his privacy.

"I feel I was used to promote their clinic," Ali said in a statement.

Jacobson, who said he has invented a breakthrough technology for regenerating nerve cells, said he was both hurt and saddened by Ali's reaction.

"I feel really awful. ... it's just that the media came on too strong and I guess he felt swamped and (Ali's wife, Lonnie) felt set up, which was not the case," Jacobson said Tuesday.

Jacobson, who lives in Jupiter, defended the decision to confirm to the media that Ali was being treated at his clinic. Jacobson said it was not an effort to capitalize on the champion's fame.

"This had nothing to do with business," Jacobson said. "All I wanted from Ali was two weeks to show the efficacy of this treatment."

Ali has returned to his home in Berrien Springs, Mich., assistant Kim Vidt said.