Participants will be randomly assigned to either treatment or placebo group. The initial treatment phase will last for 4 weeks. At the end of the first 4 weeks, the treatment will be reversed after a 3 day washout period. During the 2nd intervention period, the study drug will be reversed (those receiving acetaminophen will receive the placebo drug and vice versa). The second treatment phase will last for 4 weeks. At the end of 2nd treatment phase, all study treatments will be discontinued