McLean said he checked himself into a rehab clinic for "personal reasons," according to the magazine.
"With 2011 being a busy year for Backstreet, I want to be healthy and perform and sing for people at my very best and happiest," he said in a statement. "None of this will affect our current tour plans and I look forward to seeing everyone really soon! Thank you for all of your support and respecting my family and friends privacy during this time."
The 33-year-old singer first hinted at his 2011 plans on Jan. 9. "Thank u all for my bday wishes and tweets:)! Its gonna be a great year! I love u all and wish me luck! I start my sober journey tomm," he tweeted.
This is McLean's third stint in rehab. He sought treatment for depression, anxiety and excessive consumption of alcohol in 2001. He returned to rehab a year later for issues including depression and alcohol abuse.
McLean is hitting the road this summer on the Backstreet Boys' joint tour with fellow boy band New Kids on the Block.