Mindfulness-based interventions improve cognition

A meta-analytic review of randomized-controlled trials evaluating the effects of mindfulness-based interventions on cognition found that these interventions consistently yield small-to-moderate improvements in global cognition and various cognitive subdomains. The improvement levels are practically meaningful. The study was published in Health Psychology Review.

Mindfulness is the practice of paying deliberate and non-judgmental attention to the present moment, cultivating awareness of one’s thoughts, feelings, and surroundings to promote mental clarity, emotional balance, and overall well-being. It is often used in psychotherapy as a therapeutic technique to help individuals manage stress, reduce symptoms of anxiety and depression, enhance self-awareness, and develop healthier coping mechanisms by incorporating mindfulness practices and principles into their treatment.

Mindfulness-based interventions typically involve practices like meditation, deep breathing, and body scans to develop mindfulness skills. These interventions have been used to reduce stress, anxiety, depression, and improve overall mental health, as well as enhance one’s ability to cope with various life challenges. Studies have shown that they can also improve executive functioning by teaching individuals to not react to cognitive and emotional content.

Study authors Nur Hani Zainal and Michelle G. Newman wanted to systematically assess the strength of effects of mindfulness-based interventions on global cognition and the following unique cognitive subdomains: orienting, executive attention, working memory accuracy and latency, inhibition accuracy and latency, shifting accuracy and latency, sustained attention (accuracy or intra-individual coefficient of variation), subjective cognitive functioning, processing speed, verbal fluency, episodic memory, and cognitive error.

These cognitive subdomains encompass various aspects of mental functioning. Orienting involves directing attention to specific sensory stimuli.

Executive attention relates to cognitive control, aiding in planning and decision-making. Working memory measures the accuracy of temporary information storage and manipulation, with latency reflecting processing speed.

Inhibition assesses the ability to suppress irrelevant information. Shifting evaluates task-switching ability, while sustained attention measures focus stability. Subjective cognitive functioning involves self-perception of cognitive abilities. Processing speed gauges how quickly individuals process information. Verbal fluency assesses language-related skills. Episodic memory relates to recalling past experiences, and cognitive error identifies and quantifies thinking mistakes.

The researchers acknowledged a key limitation of prior meta-analyses: the inclusion of studies lacking randomization and adequate experimental control. To address this, they conducted a meta-analysis focusing solely on randomized controlled trials to evaluate the efficacy of mindfulness-based interventions.

The study authors searched for published papers on randomized controlled trials involving participants without prior meditation experience, employing control groups, and including pre-and post-assessment as well as at least two mindfulness-based training sessions. This search in scientific journal databases yielded 111 studies fitting these criteria. In their analysis, the researchers considered various factors: the participants’ characteristics (age, health conditions, etc.), the nature of the treatment, and the overall attributes of the study, including its quality and the presence of fidelity checks.

The combined studies analyzed included 9,538 participants, averaging 34 years in age. However, there was a wide age range among participants, from 4 to 81 years. Females constituted 58% of the study participants. The size of the individual studies varied, ranging from 14 to 424 participants. These studies were conducted across 22 countries, with 41% originating from the United States. Among the studies that reported on participants’ ethnicity, 61% of participants were identified as white.

The analysis of effect sizes revealed that mindfulness-based interventions positively influenced global cognition, executive attention, working memory, accuracy in inhibitory control and cognitive flexibility, sustained attention accuracy, and subjective cognitive functioning, in comparison to control groups. The magnitude of these effects varied across studies, ranging from small to large, with effects on global cognition generally being more substantial.

Effects were weaker on older individuals and females. Studies of better quality tended to report stronger effects of mindfulness-based interventions compared to controls. The size of the effect did not depend on the number of sessions, treatment duration, or on the percentage of participants that completed the study.

Non-standard mindfulness-based interventions had stronger effects than standard ones on global cognition, sustained attention accuracy and subjective cognitive functioning. Treatments delivered face-to-face were substantially more effective than self-guided interventions.

“MBIs [mindfulness-based interventions] showed positive effects on executive attention, inhibition accuracy, WM [working memory] accuracy, shifting accuracy, sustained attention accuracy, intra-individual coefficient of variation, and subjective cognitive functioning,” the study authors concluded.

“However, MBIs did not significantly positively affect orienting, WM latency, inhibition latency, shifting latency, processing speed, verbal fluency, episodic memory, and cognitive error. Overall, MBIs improved EF [executive functioning] and sustained attention accuracy-based rather than latency-based outcomes, likely because mindfulness practices promote present-moment awareness and effective goal attainment over efficiency”.

The study sheds light on the effects of mindfulness-based interventions on cognition. However, it also has limitations that need to be taken into account. Notably, study authors were not able to account for variations in the delivery of the training i.e., the quality of the training and how well it was conducted in practice. Additionally, it remains unknown which components of mindfulness-based interventions produce the observed effects.

The paper, “Mindfulness enhances cognitive functioning: a meta-analysis of 111 randomized controlled trials”, was authored by Nur Hani Zainal and Michelle G. Newman.

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