Is there any strong empirical support that "casual" (10-20 minutes per day) mindfulness meditation leads to lasting cognitive improvements? I want to emphasize that I'm not referring to the intense mindfulness-based cognitive therapy (MBCT), but instead just 10-20 minutes of daily mindfulness meditation (MM), perhaps guided by a smartphone app.

It's usually claimed that MM leads to improvements in the prefrontal cortex (enhanced focus, working memory etc.) and the amygdala (reduced depression, anxiety, stress etc.).  

I have read recent studies claiming that mindfulness meditation is no more effective than watching a documentary, is counterproductive at work etc. (Some of these studies may have been context-specific.) Anecdotally, I've done MM myself on-and-off for several years and didn't notice any significant improvements in the areas listed above.  

Due to publication bias, p-hacking, the reproducibility crisis etc. and my own personal experience, I'm skeptical that MM does anything significant (noticeable changes) and/or lasting (after the meditation, during the day).  

Is there a large-scale, pre-registered replication effort to support the benefits of 'casual' MM (i.e., not the more intense MBCT)?
The following is the empirical support I can find

Beauchemin, J., Hutchins, T. L., &amp; Patterson, F. (2008). Mindfulness meditation may lessen anxiety, promote social skills, and improve academic performance among adolescents with learning disabilities. Complementary Health Practice Review, 13(1), 34-45. DOI: 10.1177/1533210107311624
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All outcome measures showed significant improvement, with participants who completed the program demonstrating decreased state and trait anxiety, enhanced social skills, and improved academic performance. Although not directly assessed, the outcomes are consistent with a cognitive-interference model of learning disability and suggest that mindfulness meditation decreases anxiety and detrimental self-focus of attention, which, in turn, promotes social skills and academic outcomes.

 

Moore, A., &amp; Malinowski, P. (2009). Meditation, mindfulness and cognitive flexibility. Consciousness and cognition, 18(1), 176-186. DOI: 10.1016/j.concog.2008.12.008
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Overall the results suggest that attentional performance and cognitive flexibility are positively related to meditation practice and levels of mindfulness. Meditators performed significantly better than non-meditators on all measures of attention. Furthermore, self-reported mindfulness was higher in meditators than non-meditators and correlations with all attention measures were of moderate to high strength. This pattern of results suggests that mindfulness is intimately linked to improvements of attentional functions and cognitive flexibility. The relevance of these findings for mental balance and well-being are discussed.

 

Zeidan, F., Johnson, S. K., Diamond, B. J., David, Z., &amp; Goolkasian, P. (2010). Mindfulness meditation improves cognition: Evidence of brief mental training. Consciousness and cognition, 19(2), 597-605. DOI: 10.1016/j.concog.2010.03.014
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Our findings, with naïve participants learning mindfulness techniques by means of a brief training format, are consistent with those that have been reported for adept meditators. Four days (20 min/day) of MM training was effective in signifi- cantly increasing mindfulness scores in comparison to an active control group. Our brief MM training protocol promoted sig- nificant effects on several cognitive tasks that require sustained attention and executive processing efficiency (Symbol Digit Modalities Test, verbal fluency, and the hit runs on n-back task). However, no specific benefits from MM training were found with many of the mood scales, the forward and backward digit span or speed on the n-back task. It is important to note that the groups did not differ at baseline on any of the measures and had no prior meditative experience.

 

Chiesa, A., Calati, R., &amp; Serretti, A. (2011). Does mindfulness training improve cognitive abilities? A systematic review of neuropsychological findings. Clinical psychology review, 31(3), 449-464. DOI: 10.1016/j.cpr.2010.11.003
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[T]he results of the present review provide preliminary support for the notion that MMPs could provide significant benefits on several measures of cognition which seem specific for the phase of meditation training under investigation. However, further higher quality studies focusing on more standardized MMPs are needed to replicate available findings, to more deeply explore the effects of mindfulness training on further domains of cognition and to reduce discrepancies of findings deriving from systematic differences in mindfulness protocols.