New England Patriots running back Brandon Bolden was suspended for four games for using performance-enhancing drugs, the National Football League said.

The NFL declined to identify the substance that violated the league’s drug policy.

The 22-year-old’s suspension is effective immediately, the league said. He will be eligible to return to the roster Dec. 3 after the team’s game against the Miami Dolphins.

Bolden, who has missed the Patriots’ last two games with a knee injury, set career-highs in rushing attempts and yards against the Buffalo Bills on Sept. 30, finishing with 16 carries for 137 yards and a touchdown.

For the season, Bolden has totaled 43 rushes for 234 yards and two touchdowns.

The Patriots are 5-3 to lead the American Football Conference East. They host the Bills tomorrow.

To contact the reporter on this story: Nancy Kercheval in Washington at nkercheval@bloomberg.net

To contact the editor responsible for this story: Michael Sillup at msillup@bloomberg.net