Pittsburgh Penguins captain Sidney Crosby will be missing Game 4 in his team’s semifinal series against the Washington Capitals due to yet another concussion -- at least the fourth in the 29-year-old’s nearly 12-year NHL career.

Receiving multiple concussions, experts warn, can lead to severe consequences.

“We’re getting more and more concerned about the relationship between multiple concussions and later degenerative diseases,†neurologist Dr. Carmela Tartaglia of the at Toronto’s University Health Network told Â鶹´«Ã½ Channel. Those can include chronic traumatic encephalopathy and Alzheimer’s disease, Tartaglia said.

Multiple concussions, Tartaglia added, are the biggest risk factor for post-concussion syndrome, which counts headaches, nausea, blurred vision, memory loss and trouble concentrating as its symptoms.

“We don’t have any cures for concussions,†Tartaglia said. Only symptoms, she said, can be treated. “So we ask people to really put themselves out of harm’s way.â€

On Monday, in the first period of Game 3 of the series, Crosby suffered a concussion after being cross-checked in the head by Washington defenseman Matt Niskanen. Niskanen was given a five minute major and a game misconduct. Crosby missed the rest of the game.

This is not the first time the star centre has been floored by a concussion. Since 2011, multiple concussions have seen Crosby miss dozens of games, including much of the 2011-2012 season.

Tartaglia’s advice for Crosby is simple.

“Avoid any situation that could put you at risk for other concussions,†she said. “He needs to be sufficiently better so that he doesn’t place himself at risk of having another brain injury on top of the one that he’s just suffered.â€