- This pilot study investigated changes in hippocampal gray matter volume in young adults who self-reported a history of childhood maltreatment and underwent mindfulness training or remained on a waiting list
- The mindfulness group showed an increase in gray matter volume in a 130-voxel cluster in the right hippocampus, whereas the control group showed a decrease
- Two other hippocampal clusters were significantly associated with reductions in symptoms of stress and depression
- In the mindfulness group, two small hippocampal clusters showed positive associations between pre- and post-intervention changes in gray matter volume and changes in performance on a computer task of episodic memory
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Childhood maltreatment, including emotional abuse and neglect, increases the risk of psychopathology. This may be due to its impact on neural development, notably reduction of the gray matter volume of the hippocampus. Besides being important to learning and memory, the hippocampus has a key role in regulating stress, which is thought to be a primary predictor of anatomic changes in the hippocampus among maltreated children.
In a previously reported pilot study published in Frontiers of Psychology, researchers at Massachusetts General Hospital observed a beneficial effect of a mindfulness-based behavioral intervention on the psychological condition of young adults who self-reported childhood maltreatment. Among the 43 subjects, the greater the number of intervention sessions attended, the greater the reductions in stress, anxiety and depression, after controlling for severity of maltreatment.
Reporting on the same cohort, Diane Joss, PhD, researcher at McLean Hospital and Massachusetts General Hospital, Sara W. Lazar, PhD, research associate in the Department of Psychiatry at Massachusetts General Hospital, and Martin H. Teicher, MD, PhD, at McLean Hospital, add that the mindfulness program was associated with increased gray matter volume in the hippocampus and improved performance on a test of episodic memory. They published their results in Psychiatry Research: Neuroimaging.
During each of the three waves of recruitment, participants were assigned to an eight-week mindfulness intervention (n=21) or waiting list (n=21). Subjects on the waiting list were offered the mindfulness intervention in the following wave, and six of them completed it.
The mindfulness intervention covered topics such as mindfulness meditation, attention and awareness, responding versus reacting to stress, coping strategies and handling difficult emotions and communications.
Within a month before the start of the mindfulness intervention or waiting period, all participants underwent an MRI anatomic scan and completed a computerized episodic memory task outside the scanner. Within a month after the intervention was finished, all participants repeated the scan and computer test.
Improvement in Memory
Pre- and post-intervention testing showed that both groups improved their accuracy on the episodic memory task. In the mindfulness group, two small clusters in the left hippocampus (80 and 53 voxels, respectively) showed positive associations between changes in gray matter volume and changes in accuracy on the memory task.
Increase in Hippocampal Volume
At a 130-voxel cluster in the right hippocampus, the mindfulness group showed a 0.76% increase in gray matter volume after the intervention, compared with a 0.78% decrease in the control group after the waiting period. The between-group difference was statistically significant.
Increases in two other hippocampal clusters were significantly associated with improvement on the Perceived Stress Scale and the Beck Depression Inventory.
Hope for the Future
In previous studies, antidepressant therapy led to increased hippocampal volume among patients with post-traumatic stress disorder, and environmental enrichment and physical exercise reversed stress-related reductions in neurogenesis. Although the mechanism is unclear, this study suggests mindfulness training has similarly beneficial effects on the hippocampus that are accompanied by clinical improvement.
Learn more about the Lazar Lab for Meditation Research
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