Holzel et al (Mindfulness and Brain scans) Flashcards
AIM:
🔹Holzel et al. planned their study to overcome the potential problem experienced in earlier cross-sectional studies by using a longitudinal design.
🔹The aim was to identify changes in specific brain regions, and the whole brain, by comparing grey matter concentration before and after a mindfulness course.
SAMPLE:
Participants were recruited from people already enrolled on MBSR courses at the University of Massachusetts.
The initial experimental sample of 8 males and 10 females fell to 16 as 2 males left after the first MRI session due to discomfort. The remaining sample had a mean age of 38 years and included 13 Caucasian, 1 Asian, 1 African American and 1 multi-ethnic participant.
The Control sample consisted of seven males and ten females with a mean age of 39 years and included 13 Caucasian, 2 Asian, 2 African American and 1 Hispanic participant.
These two groups did not differ in terms of their educational level.
BACKGROUND:
Mindfulness involves thinking and sensations, and this information is processed by the brain. It could therefore be possible to study what parts or part of the brain are involved in the changes in attention and thinking associated with mindfulness.
🔹Early studies studies of mindfulness and the brain used the EEG (as used by Dement and Kleitman in core study 1) but it is now possible to use the more detailed process of MRI. This neuroimaging procedure enables precise measurement to be taken of the brain. For example, the size of different structures can be calculated and the amount of grey matter (the cell bodies of neurons) compared to white matter (the axons of neurons). MRI is able to detect small structural changes in the concentration of grey matter over time, and such changes are apparent in different kinds of training, including the learning of physical skills, and cognitive skills such as juggling, medical students revising for their exams and mirror reading.
PROCEDURE: 1
The experimental and control groups both completed the Five Facet Mindfulness Questionnaire (FFMQ), which has 39 items that measure :
🔹Observing: noticing internal and external stimuli, such as thoughts, feelings and sensations, including sights, sounds and smells.
🔹Describing: mentally labelling these observations with words.
🔹Acting with awareness: being attentive to current actions rather than responding automatically or absentmindedly.
🔹Non-judging (of inner experience): not evaluating sensations, cognitions or emotions.
🔹Non-reactivity (to inner experience): allowing thoughts and feelings to drift in and out.
PROCEDURE: 2
Each item on the FFMQ is a statement and is responded to on a five-point Likert-type scale. The questionnaire was completed by the experimental group before and after the MBSR course. The control group also completed the questionnaire twice. In each group, 14 participants provided usable data at both time points.
PROCEDURE: 3
Participants in both the experimental and control groups had MRI scans of their brains on two occasions. For the experimental group, these were during the two weeks before and two weeks after the eight-week MBSR intervention (an average gap of approximately 56 days). Participants in the control group had an average gap of approximately 66 days between their two scans. These are called the ‘pre’ and ‘post’ tests.
The data from the MRI scans was used in two ways: to produce a ‘region of interest’ analysis, of particular brain areas, and to provide a ‘whole-brain analysis’. The whole-brain analysis was used to explore other regions potentially affected by the mindfulness intervention.
Finally, participants reported the time they spent on formal homework exercises over the eight weeks, and the amount of time spent on each of the three exercises (body scan, yoga and sitting meditation).
RESEARCH DESIGN:
This was an experiment using a longitudinal design, as a group of participants was tested before and after an intervention.
EXPERIMENTAL DESIGN and VARIABLES:
🔹The experiment had an independent measures design as there was an MBSR group and a control group of participants who had not experienced mindfulness intervention.
🔹The IV was exposure to an eight-week mindfulness-based intervention course (MBSR).
🔹The DV was the change in grey matter assessed using MRI scans and the participants completed questionnaires to measure 5 mindfulness scales (both before and after intervention).
RESULTS: 1
Participants in the experimental group spent an average of 27 minutes per day on mindfulness homework during the course. None of the three samples were significantly correlated. For eg: the correlation coefficient between body scan and sitting meditation was r = - 0.26.
RESULTS: 2
Useable FFMQ data from both time points was obtained from 14 MBSR and 14 control participants. Participants in the MBSR group significantly increased their mindfulness scores on three of the subscales between the pre and post questionnaires (acting with awareness, observing and non-judging). Furthermore, when this change was compared to that of the control group which was not expected to change at all - the changes in mindfulness scores of the MBSR group were significantly greater on all three subscales.
In the test of grey matter concentration in the left hippocampus, no differences were detected between the MBSR and control groups at the start of the study. Nor were there any changes in grey matter concentrations in the control group between the two test points. Importantly, changes in this region of interest were detected in the MBSR group between the pre- and post-tests, based on a group size of 16. This change did not, however, correlate with either the amount of homework completed by the participant or changes in their FFMQ scores. The grey matter concentration in other regions of interest did not show significant changes between the pre- and post- intervention tests.
RESULTS: 3
The results from the whole-brain analysis also revealed changes. Four clusters in the brains of participants in the MBSR group were found to have significantly increased in grey matter concentration between the pre- and post-tests. These clusters were in the posterior cingulate cortex, the left temporo-parietal junction and in two parts of the cerebellum (the lateral cerebellum and the cerebellar vermis/brainstem). These differences were also significantly greater than changes in corresponding areas of the brains of participants in the control group. As with the regions of interest findings, there were no correlations between the changes in these four areas and the amount of homework completed by the participant or changes in their FFMQ scores. In the MBSR group, no parts of the brain were found to have significant decreases in grey matter concentration after the MBSR intervention although there were some small reductions in grey matter concentration in the control group over the study period.
CONCLUSION:
🔹Structural changes in the ROI such as the left hippocampus shows an increase in grey matter concentration after an eight-week participation in MBSR course. (This finding suggests that localized increases or decreases in hippocampal volume that have been demonstrated in other situations may happen in response to mindfulness meditation. Since the hippocampus plays a role in learning and memory, this suggests that during the MBSR course participants had learning experiences that changed the hippocampal grey matter.)
🔹Furthermore, increases in grey matter concentration are also observed in the left temporo-parietal junction (TJP), posterior cingulate cortex (PCC), and cerebellum of the MBSR group but not the control group also suggest that participation in an eight-week mindfulness course causes structural changes in these brain regions.
🔹The TJP is important in the way we see ourselves or ‘self-referential processing’, for example the unity of our sense of self and our physical body. When processing in the TJP is impaired, this self-referential system can become faulty and can lead to out-of-body experiences. This links to the role of mindfulness training in learning to perceive the body as a ‘complete whole’.
🔹Similarly, the PCC has a role in the way we judge the relevance of stimuli to ourselves, for example assessing how important an experience is to our emotional or autobiographical context. These functions arise in mindfulness too, for example in noticing internal and external stimuli and being attentive to moment-to- moment experiences of such stimuli.
In addition, one of the key areas of the cerebellum identified as changing due to the mindfulness practice has a role in regulating emotions and cognition for healthy psychological functioning.
🔹The areas of the hippocampus, TPJ and PCC were found to change in response to the mindfulness intervention is interesting as they, together with parts of the prefrontal cortex, form a brain network with many related functions, such as recalling the past, thinking about the future, and considering others’ viewpoints such as in turn-taking. Together, these areas contribute to the way that autobiographical information enables the individual to consider alternative perspectives. This is a crucial step in achieving a mindful state.
EVALUATION (STRENGTHS):
🔹High Validity -
Using MRI scanners to measure brain structure gives quantitative and objective data as the recorded volumes themselves do not need the researcher to interpret any results, which in turn increases validity.
🔹High Reliability -
The study has high levels of controls, for example, the duration of the MBSR training was the same (eight-week long course), and all participants administered the same FFMQ, and were scanned through the same MRI scanner, which makes the procedure standardized and easy to replicate and achieve the same results, which increase the reliability of the study.
EVALUATION (WEAKNESSES):
🔹Low Generalizability - participant attrition
As this is a longitudinal study, there is a possibility of participant attrition, which is when participants withdraw from a study, as it is at times not practical or possible for all participants to remain in a study over a long time period, which can lower the generalizability. In this study, two participants exercised their right to withdraw.
🔹Low Validity - social desirability bias
Since the FFMQ was a self-report measure, there is a possibility of participants providing socially desirable responses which can lower validity. Furthermore, the responses were close ended, and this would restrict participants from providing more detailed, open-ended responses, and as a result, lowers validity.
ETHICAL ISSUES:
The study raised a few ethical issues:
🔹To ensure the participants were protected during scanning, none accepted for the study had any metal implants, which could present a risk of physical harm, or claustrophobia, which could present a risk of psychological harm.
🔹Also, following the right to withdraw, two participants left the study after the first MRI scan as they found the procedure uncomfortable.
🔹All of the participants were experiencing stress, identified through doctor or self-referral.
🔹The participants allocated to the control group had to wait for at least eight weeks before they could receive assistance. This delay in help risks a failure to protect participants from harm. However, it is unknown whether there was a capacity for people to begin the course in advance of this time, so this may have been an issue beyond the researcher’s control.
