The day after he turned 40 – and with no end to his career in a dangerous sport in sight – Tom Brady was vague on whether he had sustained concussions last season.

Concussions in the NFL have been under increased scrutiny in recent years. One of Brady’s former team-mates, Junior Seau, killed himself in 2012 and was found to have the degenerative brain condition CTE, or chronic traumatic encephalopathy. A recent study of the brains of deceased NFL players showed that 110 out of 111 had signs of CTE. The study also claimed that longer careers exposed players to more severe cases of CTE. Brady is preparing to start his 18th season in the NFL.

Earlier this year Brady’s wife, Gisele Bundchen, said the New England Patriots quarterback has a history of concussions, including one suffered last season when he took his team to victory in the Super Bowl.

On Friday, Brady addressed the subject while speaking to reporters at the Patriots’ training facility. “I don’t want to get into things that happened in my past, certainly medical history and so forth. I really don’t think that’s anybody’s business,” Brady said. “What happened last year; I’m focused on this year and improving and working on things I need to get better at.

“So that’s how I approach everything. I’m not sitting here worried about last year, or five years ago. There are other people that do worry about that – my wife, or my parents, or my sisters, people that love me and care about me. But I do the best I can do to be prepared to play – mentally and physically – and I give the game everything I can.”

Brady said he was aware of the dangers football brings. “It’s a contact sport and I think we all understand that,” he said. “There are a lot of great benefits that football brings you but certainly you can be put in harm’s way. So you just do the best you can do as a player and obviously it’s great that there is more awareness for those types of things. That’s been a very important topic, certainly. But you just try to be proactive and take care of your body the best way you can.”

Brady has said he plans to play for at least another five years, although in February he said Bundchen wants him to retire from the game: “If it was up to my wife, she would have me retire today. She told me that last night three times.”