IndyCar rookie Oliver Askew will not compete in next week's doubleheader at Indianapolis because of concussion-like symptoms that date to his crash in the Indianapolis 500 last month.

Arrow McLaren SP will use Helio Castroneves in the No. 7 Chevrolet at Indianapolis.

Askew told The Associated Press on Thursday he has been experiencing dizziness, sleeping difficulties, irritability, headaches and confusion since he crashed late in the Aug. 23 race. He continued to race and tried to “play through it” until friends and family encouraged him to seek medical treatment.

Askew sought treatment at the University of Pittsburgh Medical Center’s sports medicine concussion program, the same place NASCAR star Dale Earnhardt Jr. received care. He said the injury has a “100% recovery rate” and he believes he will be able to race in the IndyCar season finale next month at St. Petersburg.

His performance had been obviously off in the four races since his crash at Indianapolis. Askew, last year's Indy Lights champion, had finished third and sixth at Iowa — the previous two races before Indianapolis.

The 23-year-old was part of a crash on the start at Gateway the week after the Indy 500 and he has not finished higher than 14th in the four races.

Castroneves, a three-time Indy 500 winner, has made his last 310 starts with Team Penske. He's a full-time driver with Penske's sports car arm, but that program is ending this year. The Brazilian is seeking a full-time return to IndyCar.