NEW YORK (AP) - Troy Aikman says he has no symptoms from his 10 concussions during his Hall of Fame career with the Dallas Cowboys.

Defensive players, he thinks, are more at risk than quarterbacks.

Aikman does get migraine headaches.

But he's had them all his life and he says they're not related to football.

Last week, a study of more than 2,500 retired NFL players found that those who had at least three concussions during their careers had triple the risk of clinical depression as those who had none.

"I think people got the impression that Steve Young and I were forced out by concussions. For me, it was more my back," said the 40-year-old Aikman who retired six years ago.

"I've had no problems since," he added, saying he hasn't suffered from depression. "From my perspective, I think I got off relatively lightly.

I think defensive players are far more at risk than quarterbacks they get hit on every play and may often have concussions they don't know about."

Aikman said his migraines are triggered by cigarette smoke and airline travel, which he does more now in his capacity as a broadcaster than he did as a player.

He said his headaches were diagnosed as migraines only after he consulted a doctor last year.

Aikman said that while migraines have been thought to effect mostly women, studies show that 7 million males 6 percent of the population get them.

"I think a lot of men think they can tough it out," Aikman said. "My advice to them is to see their doctors."

Aikman praised the NFL for its recent decision to run baseline tests on all players in training camp so the league can later determine if their brains have been damaged from hits to the head.

"The fact that doctors will now have a record of how much change there has been is a huge step forward," he said.