AJ McLeanBackstreet Boys singer A.J. McLean has checked himself into rehab.

"For personal reasons, I've checked myself into a rehab clinic," McLean says in a statement (via PEOPLE). "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. 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."

While he gave no reason as to why he is seeking treatment, the singer has battled substance abuse issues in the past and went to rehab in 2001 and 2002 for alcohol and cocaine abuse.