This small study shows that sustained changes in the brain and immune  function occur after mindfulness meditation training and practice during the study.

Sustained increases in the left frontal region of the brain were detected, on a sustained basis, in the control group.  This has been associated with more optimistic and emotionally positive mental states.

Separately, biomarkers of immune response were checked by evaluating antibody development following flu shots.  The control group had significantly better immune response to flu shots following the mindfulness training and practice period.

University Of Wisconsin-Madison (2003, February 4). University Of Wisconsin Study Reports Sustained Changes In Brain And Immune Function After Meditation. ScienceDaily.­/releases/2003/02/030204074125.htm