CHICAGO — Patriots rookie linebacker Brandon Spikes tested positive for a substance typically found in medications used to treat attention-deficit hyperactivity disorder, according to multiple reports yesterday.

While the specific drug is not known, according to Comcast SportsNet New England, it is believed to have contained amphetamines, which are banned by the NFL.

Terry Watson, Spikes’s agent, declined to comment on the reports.

Spikes, a second-round draft pick out of Florida, was suspended for four games Friday for violating the league’s policy on performance-enhancing substances and will not be eligible to return until the playoffs.

In a statement released on Friday, Spikes said the substance was “a medication that I should have gotten clarification on before taking. It was not a performance enhancer or an illegal drug.’’

The suspension will not be appealed, Watson said Friday.

In place of Spikes, Gary Guyton and rookie Dane Fletcher figure to get more playing time this afternoon against the Bears.

Spikes is not allowed to be at the Patriots facility during the suspension and will not be paid.

Three outs The Patriots downgraded cornerback Jonathan Wilhite (hip) and defensive linemen Myron Pryor (back) and Mike Wright (concussion) to “out’’ for today’s game. The three have been out for some time. Wilhite is going to miss his fourth consecutive week, Pryor has missed five straight games, and Wright will be out for third straight week.

Weather is frightful A Midwest storm that canceled some flights and delayed many others should make conditions interesting today.

The forecast is calling for a combination of snow and rain along with wind gusts of more than 40 miles per hour. Temperatures are expected to be in the teens, with windchills in the single digits.

Patriots kicker Shayne Graham, who played eight seasons in Cincinnati, said cold air can affect the distance of kicks. He said the fields at Gillette Stadium get a fair amount of wind, which allows him to practice in a variety of situations.

“That’s always something you deal with,’’ Graham said. “It’s going to be different each time. You don’t really do anything different with the ball when it’s cold. You just do your best to focus on what your technique is and your execution.’’

Graham also will check the condition of the playing surface at Soldier Field, which was resodded last week.

“You try to adapt the best you can,’’ said Graham. “Sometimes it can be really bad, but I’m sure they’ve taken care of it and I’m sure it will be in the best possible shape.’’

North stars The Patriots are 2-0 against NFC North opponents, with wins over the Vikings and Lions. After the Bears, the Patriots also must play the Packers. Since 2002, the Patriots are 9-1 against the NFC North . . . Tom Brady will play in Soldier Field for the first time. He faced the Bears in 2002, but the game was in Champaign, Ill. When the Patriots last played at Soldier Field, in 2000, Brady was with the team but didn’t play. “I was eating nachos, I think,’’ he said.

Monique Walker can be reached at mwalker@globe.com.

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