Reduced interference in working memory following mindfulness training is associated with increases in hippocampal volume

Proactive interference—when old information disrupts learning new material—can be reduced by mindfulness training. In a randomized trial, 79 participants completed either a 4-week web-based mindfulness program or a creative writing control. The mindfulness group showed lower proactive interference error rates after training. No group differences in hippocampal volume emerged, but improvements in proactive interference were linked to volume increases in the left hippocampus. These findings suggest mindfulness training protects against proactive interference, with benefits tied to hippocampal structural changes, and may have implications for conditions like aging, depression, PTSD, and childhood adversity where working memory and hippocampal volume are compromised.

Study at a glance

Abstract

Proactive interference occurs when previously relevant information interferes with retaining newer material. Overcoming proactive interference has been linked to the hippocampus and deemed critical for cognitive functioning. However, little is known about whether and how this ability can be improved or about the neural correlates of such improvement. Mindfulness training emphasizes focusing on the present moment and minimizing distraction from competing thoughts and memories. It improves working memory and increases hippocampal density. The current study examined whether mindfulness training reduces proactive interference in working memory and whether such improvements are associated with changes in hippocampal volume. 79 participants were randomized to a 4-week web-based mindfulness training program or a similarly structured creative writing active control program. The mindfulness group exhibited lower proactive interference error rates compared to the active control group following training. No group differences were found in hippocampal volume, yet proactive interference improvements following mindfulness training were significantly associated with volume increases in the left hippocampus. These results provide the first evidence to suggest that (1) mindfulness training can protect against proactive interference, and (2) that these benefits are related to hippocampal volumetric increases. Clinical implications regarding the application of mindfulness training in conditions characterized by impairments to working memory and reduced hippocampal volume such as aging, depression, PTSD, and childhood adversity are discussed.