Persinger. M.A. (1992). Enhanced incidence of 'the sensed presence' in people who have learned to meditate: Support for the right hemispheric intrusion hypothesis. Perceptual and Motor Skills, 75, 1308-1310. * [PubMed]
“The effect size suggests that learning a meditation technique is contraindicated for subpopulations, such as borderline, schizotypal, or dissociative personalities who display very fragile self-concepts.”
This survey of TM meditators indicated significantly higher scores in religiosity and paranormal phenomena reporting (e.g., depersonalization, auditory hallucinosis) than in nonmeditating controls. in Lansky & St. Louis, 2006.