Scientists who monitored the group noted "measurable changes" in areas of the brain associated with memory, empathy and stress.
The meditators - who practised mindfulness meditation - achieved the changes in just eight weeks, say researchers from the Massachusetts General Hospital.
Images of the group's brains were taken before and after the two-month study. During the study, the meditators practised mindfulness for around 27 minutes a day. At the end of the eight weeks, the researchers noted increased grey-matter density in the hippocampus - an area of the brain associated with learning and memory - and in brain structures that relate to self-awareness, compassion and introspection.
Mindfulness meditation, based on the teachings of the Buddha, is a non-judgemental awareness of sensations, feelings and states of mind.
(Source: Psychiatry Research: Neuroimaging, 2011; 191: 36).