Neural correlates of mindfulness meditation-related anxiety relief

Abstract

Anxiety is the cognitive state related to the inability to control emotional responses to perceived threats. Anxiety is inversely related to brain activity associated with the cognitive regulation of emotions. Mindfulness meditation has been found to regulate anxiety. However, the brain mechanisms involved in meditation-related anxiety relief are largely unknown. We employed pulsed arterial spin labeling MRI to compare the effects of distraction in the form of attending to the breath (ATB; before meditation training) to mindfulness meditation (after meditation training) on state anxiety across the same subjects. Fifteen healthy subjects, with no prior meditation experience, participated in 4 d of mindfulness meditation training. ATB did not reduce state anxiety, but state anxiety was significantly reduced in every session that subjects meditated. Meditation-related anxiety relief was associated with activation of the anterior cingulate cortex, ventromedial prefrontal cortex and anterior insula. Meditation-related activation in these regions exhibited a strong relationship to anxiety relief when compared to ATB. During meditation, those who exhibited greater default-related activity (i.e. posterior cingulate cortex) reported greater anxiety, possibly reflecting an inability to control self-referential thoughts. These findings provide evidence that mindfulness meditation attenuates anxiety through mechanisms involved in the regulation of self-referential thought processes.

Keywords: anxiety; arterial spin labeling; fMRI; mindfulness meditation.

© The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Figures

Fig. 1

The SAI was administered before and after each MRI session. In first half of MRI session one, 1 heat (49°C) and 1 neutral (35°) series was randomly presented in each fMRI block. Furthermore, subjects were instructed to close their eyes and reduce movement (rest), which served as the no-distraction condition. In the second half of MRI session one, 1 heat (49°C) and neutral (35°) series was randomly presented in each fMRI block. Before anatomical acquisition, subjects were instructed to ‘meditate by focusing on the changing sensations of the breath (ATB).’ ATB served as the self-distraction condition when compared to rest and mindfulness meditation after training. Subjects then participated in 4 days of mindfulness meditation training (see Mindfulness-Based Mental Training for more detail). After successful completion of meditation training, subjects returned for MRI session 2. In first half of MRI session 2, two heat (49°C) and two neutral (35°) series was randomly presented in each fMRI block. Similar to MRI session 1, in the first half of MRI session 2, subjects were instructed to close their eyes (rest). Afterwards, subjects were instructed to ‘begin meditating by focusing on the changing sensations of the breath (‘mindfulness-based attention to breath’—meditation). In the second half of MRI session 2, 2 heat (49°C) and 2 neutral (35°) series was randomly presented in each fMRI block. The presentation of noxious vs neutral scans was counterbalanced across subjects to minimize potential order effects.

Fig. 2

State anxiety was significantly reduced in every session in which subjects meditated. ATB did not significantly reduce state anxiety. * = P < 0.05. MRI = MRI session, MT = Meditation Training.

Fig. 3

Figure 3 illustrates the individual percent state anxiety changes in MRI sessions 1 and 2. Subject numbers in MRI session 1 correspond with subject numbers in MRI session 2. Four subjects reported decreases in state anxiety in MRI session 1. There were nine subjects that reported decreases in state anxiety in MRI session 2.

Fig. 4

Anxiety relief during ATB was associated with greater activity in areas such as the left putamen (1st row). Meditation-related anxiety relief was associated with greater activity in areas such as the anterior insula, ACC and the ventro-medial medial prefrontal cortex (vmPFC; 2nd row). Increases in state anxiety were associated with increased PCC activation (2nd row). ATB-related anxiety changes were associated with activation in PCC, middle frontal gyrus, hippocampus, lateral occipital lobe and the right putamen when compared to meditation-related anxiety changes (3rd row). When contrasted to brain regions involved in ATB-related anxiety changes, brain regions involved in meditation-related anxiety alterations were found in the ACC, anterior insula, putamen and SII (4th row). Note: fMRI series with noxious stimulation were not included in analyses corresponding to the first two rows. One noxious stimulation series, per condition (3rd row: rest + neutral, rest + heat, ATB + neutral, ATB + heat; 4th row: rest + neutral, rest + heat, meditation + neutral, meditation + heat), was included for the analyses corresponding with the last two rows of the figure.