 Because our sample size will be relatively small, participants will be randomized to minocycline or placebo through a randomization stratification approach. This approach will ensure that both groups will have a similar distribution regarding baseline performance in the cognitive tests. Participants will be gathered into groups strata defined by their performance in the neuropsychological tasks baseline. Participants within each stratum will be randomized to one of two treatment groups - minocycline and placebo - according to a block randomization of four and using a randomization list generated by a computer that will take into account the study entrance order. These groups are defined as follows: 