Sex-divergent findings re hippocampal dimensions

Luders, E., Thompson, P. M., & Kurth, F. (2015). Larger Hippocampal Dimensions in Meditation Practitioners: Differential Effects in Women and Men. Frontiers in Psychology, 6, 186. To access full text, go to Abstract and retrieve provisional PDF.

hippopotamus-baby-beautiful-164-1On average, the human hippocampus shows structural differences between meditators and non-meditators as well as between men and women. However, there is a lack of research exploring possible sex effects on hippocampal anatomy in the framework of meditation.

Thus, we obtained high-resolution magnetic resonance imaging data from 30 long-term meditation practitioners (15 men / 15 women) and 30 well-matched control subjects (15 men / 15 women) to assess if hippocampus-specific effects manifest differently in male and female brains.

Hippocampal dimensions were enlarged both in male and in female meditators when compared to sex- and age-matched controls. However, meditation effects differed between men and women in magnitude, laterality, and location on the hippocampal surface. Such sex-divergent findings may be due to genetic (innate) or acquired differences between male and female brains in the areas involved in meditation and/or suggest that male and female hippocampi are differently receptive to mindfulness practices.

Increases gray matter concentration

Hölzel, B.K., et al. (2011). Mindfulness practice leads to increases in regional brain gray matter density. Psychiatry Research, 191 (1), 36-43. Full text (unedited manuscript).

From the Abstract: Therapeutic interventions that incorporate training in mindfulness meditation have become increasingly popular, but to date little is known about neural mechanisms associated with these interventions. Mindfulness-Based Stress Reduction (MBSR), one of the most widely used mindfulness training programs, has been reported to produce positive effects on psychological well-being and to ameliorate symptoms of a number of disorders.

Here, we report a controlled longitudinal study to investigate pre-post changes in brain gray matter concentration attributable to participation in an MBSR program. Anatomical magnetic resonance (MR) images from 16 healthy, meditation-naïve participants were obtained before and after they underwent the 8-week program.

Changes in gray matter concentration were investigated using voxel-based morphometry, and compared with a waiting list control group of 17 individuals. Analyses in a priori regions of interest confirmed increases in gray matter concentration within the left hippocampus. Whole brain analyses identified increases in the posterior cingulate cortex, the temporo-parietal junction, and the cerebellum in the MBSR group compared with the controls.

The results suggest that participation in MBSR is associated with changes in gray matter concentration in brain regions involved in learning and memory processes, emotion regulation, self-referential processing, and perspective taking.