Backstreet Boy AJ in Rehab

July 10 -- Is this the end of the Backstreet Boys? Teen heartthrob AJ McLean, a member of the harmonizing boy band, is in rehab for depression and alcohol abuse, his choked-up bandmates confessed on MTV's Total Request Live yesterday.

According to his publicist, McLean's depression, ascribed to the recent death of his grandmother, has led to anxiety attacks and alcohol abuse. The 23-year-old singer "will immediately undergo a 30-day treatment," according to the statement from MSO Public Relations.

McLean's absence is forcing the quintet to cancel all shows from July 9 (Boston) through Aug. 4 (Edmonton, Alberta). The tour will pick up on Aug. 7 in Vancouver, British Columbia, with the dozen affected cities rescheduled in the following month.

The other four Backstreeters — Kevin Richardson, Howie Dorough, Nick Carter, and Brian Littrell — appeared deeply concerned for their bandmate on yesterday's appearance on MTV.

His Alcoholism Is 'Pretty Bad,' Says RichardsonAccording to the 29-year-old Richardson, McLean was depressed even before the death of his grandmother: "He's been burning the candle at both ends and partying quite a bit to escape it," he said. "His alcoholism is — it's pretty bad. And we're worried about him."

McLean alluded to psychological problems in an interview with Rolling Stone magazine last year, describing how he once took a baseball bat to a radio that was playing a Backstreet Boys tune after he had broken up with a girlfriend.

"When I get stressed out, I get really violent toward myself and just say, 'Screw the group! To hell with everything!' There have been times when I wake up like that and think I don't want to do this anymore," he told the magazine.

Earlier Monday, the Backstreet Boys announced they were postponing remaining sold-out concerts at Boston's FleetCenter this week after Carter, 21, injured his hands on Saturday.

Group Not Breaking UpCarter said McLean's illness doesn't mean the group is breaking up. "I don't think there is an end to this group until one of us dies," he said.