Schneider, Grim & Rainforth et al. looked at 201 men and women with coronary heart disease who took part in one of two groups: a transcendental meditation (TM) program or a health education program. After five and a half years, the TM group showed a 48% risk reduction for heart attack and stroke.
Another study by Pagnoni & Cekic compared gray matter in the brains of Zen meditators and non-meditators over a long period of time. Though gray matter ordinarily reduces with age, the gray matter of the Zen meditators did not reduce at all.
In the report, Pagnoni & Cekic stated:
The finding of a reduced rate of decline with age of both global and regional gray matter volume in meditators may in fact indicate the involvement of multiple mechanisms of neuroprotection.
Lazar & Kerr et al. reached a similar conclusion in a study on the impact of meditation on cortical thickness of the brain.
Regular practice of meditation is associated with increased thickness in a subset of cortical regions related to somatosensory, auditory, visual and interoceptive processing. Further, regular meditation practice may slow age-related thinning of the frontal cortex.
Goyal & Singh et al. studied 3515 participants in mindfulness meditation programs and found evidence of decreased anxiety, decreased depression and decreased pain.