A visit to Japan by the former captain of the USS Greeneville to apologize for last year's fatal collision between the submarine and the Japanese high school fisheries training ship Ehime Maru may worsen the psychological stress of surviving students, their therapist said Saturday.

Masaharu Maeda, a lecturer at Kurume University who is providing psychological support for nine survivors, said, "The apology will make them feel better," but he worries that the visit by retired Cmdr. Scott Waddle may cause depression and worsen posttraumatic stress disorder symptoms.

In December, Waddle will visit the families of those who died in the accident and apologize. Two of the families have requested the apology as a condition of the settlement in compensation negotiations with the U.S. Navy.

When Maeda met Friday with eight of the former students of Uwajima Fisheries High School, in Ehime Prefecture, some said they experienced problems such as difficulty in sleeping after hearing that Waddle would visit.

One student said he "definitely does not want to meet (Waddle)," Maeda said.

Six of the nine surviving students were diagnosed with PTSD symptoms in April.

"It is necessary to discuss a method of apology that takes the students into consideration, such as no direct face-to-face meeting (between Waddle and the students)," Maeda said.

Nine aboard the 499-ton Ehime Maru were killed Feb. 9, 2001, when it was struck from below by the 6,080-ton nuclear-powered submarine, which was conducting a rapid surfacing maneuver as part of a demonstration for civilian guests aboard.