Study: NCT02079948

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Methotrexate + Folic Acid
Description: Participants in the methotrexate + folic acid condition will have a~* Blood draw at each monthly visit~* Cognitive performance testing to assess memory performance~* Physical function testing to assess walking speed and measure muscle endurance~* Pain assessment testing to assess the presence and location of daily pain~* Self-reported function and quality of life to measure disability and mobility limitations, and~* Depression assessment testing to assess participants' level of depression.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Placebo + Folic Acid
Description: Participants in the placebo + folic acid condition will have a~* Blood draw at each monthly visit~* Cognitive performance testing to assess memory performance~* Physical function testing to assess walking speed and measure muscle endurance~* Pain assessment testing to assess the presence and location of daily pain~* Self-reported function and quality of life to measure disability and mobility limitations, and~* Depression assessment testing to assess participants' level of depression

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Placebo + Folic Acid
Description: Participants in the placebo + folic acid condition will have a~* Blood draw at each monthly visit~* Cognitive performance testing to assess memory performance~* Physical function testing to assess walking speed and measure muscle endurance~* Pain assessment testing to assess the presence and location of daily pain~* Self-reported function and quality of life to measure disability and mobility limitations, and~* Depression assessment testing to assess participants' level of depression

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Functional MRI Experimental Tasks
Description: Participants who are randomly assigned to the fMRI scan wil receive their study drugs at the the Baseline fMRI visit. Participants who are randomly assigned to the fMRI will also attend complete their last visit at the 6 month period.

Intervention type: PROCEDURE
Group type: PLACEBO_COMPARATOR
Intervention: Functional MRI Experimental Tasks
Description: Participants who are randomly assigned to the fMRI scan wil receive their study drugs at the the Baseline fMRI visit. Participants who are randomly assigned to the fMRI will also attend complete their last visit at the 6 month period.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Muscle Biopsy
Description: Participants who are randomly assigned to the muscle biopsy assessment of the study will receive their study drugs at the Baseline muscle biopsy visit. Participants who are randomly assigned to the muscle biopsy portion of the study will also complete their last visit at the 6 month period.

Intervention type: PROCEDURE
Group type: PLACEBO_COMPARATOR
Intervention: Muscle Biopsy
Description: Participants who are randomly assigned to the muscle biopsy assessment of the study will receive their study drugs at the Baseline muscle biopsy visit. Participants who are randomly assigned to the muscle biopsy portion of the study will also complete their last visit at the 6 month period.