New England Patriots rookie linebacker Brandon Spikes has been suspended for four games for violating the NFL's policy on performance-enhancing drugs, the team announced Friday.

"The substance was a medication that I should have gotten clarification on before taking," Spikes said in a statement. "It was not a performance enhancer or an illegal drug. The integrity of the game is very important to me. I understand the league's ruling and apologize to my teammates, the fans and the Patriots organization for this mistake."

Medication designed to treat attention deficit disorder, which included amphetamines, caused Spikes to test positive for performance enhancers, according to a report from Comcast Sports New England.

Spikes' suspension begins immediately, with Spikes eligible to return after the Patriots' final regular-season game Jan. 2.

When reached by ESPNBoston.com for comment, Spikes' agent, Terry Watson, said, "I support Brandon's statement from yesterday."

Asked specifically about reports that the medication that caused the positive test was designed to treat attention deficit disorder, Watson said, "No comment."

Spikes does not plan to appeal the suspension. He will serve it immediately to return in time for the playoffs.

The rookie from Florida is a first- and second-down player in the team's 3-4 alignment, a strong downhill player against the run. The second-leading tackler on the team, his presence will be missed against teams that feature a physical running game.