Can meditation slow cognitive decline?

Might mindfulness meditation be used to slow brain ageing by regulating connectivity between brain networks?

The relationship between brain networks can be enhanced with meditation

As we get older, we experience an inevitable decline in physical and mental functions. However, the rate of this reduction is dependent on several factors, both genetic and environmental.  It has long been contended that there is a relationship between how we use our brains and mental capacity loss. Mind-training, particularly in the form of meditation, has the potential to mediate how we age. There is a great deal of anecdotal evidence that long term meditators retain good mental function throughout their lives; I have even researched the possible link between meditation and resilience to neurodegeneration (dementia). However, progress in this area is limited by two main problems; poor understanding of the mental processes underpinning meditation and the presence of confounding variables.

Despite over eighty years of meditation research, we know relatively little about how long term meditation changes our brain. This problem is compounded because most long-term meditators are found in spiritual traditions; their lifestyles tend to be atypical. For example, committed Buddhists generally eat healthier diets, take less alcohol and are less likely to be found in stressful occupations than the general population; all factors likely to influence health. Despite these problems, some preliminary research suggests that meditation might slow ‘mental ageing’ (age-related mental decline).

One of the more convincing hypotheses is that meditation plays a role in regulating the brain’s intrinsic and extrinsic networks (I-ENs). The scientific understanding of the I-ENs is still pretty basic. But neuroscience has illustrated that two main brain networks are responsible for our internal perspectives (intrinsic) and external task-based capacities (extrinsic). These are overarching structures connected to anatomically separate parts of the brain. The default mode network (DMN) is a significant component of the intrinsic network. It includes all of those ‘default’ functions that are more active when we’re not undertaking demanding tasks, for example, daydreaming about the past or thinking about our values. The extrinsic network encompasses the task-positive network (TPN). As the name implies, it includes task-oriented and performance systems that allow us to coordinate and carry out attention-demanding activities. But the point I want to make here is that these networks are negatively correlated. Significant activity in the intrinsic network may lead to less activity in the extrinsic, and vice versa. Thus these networks are heavily interdependent; what happens in one is linked to the other.

We can be reasonably confident that abnormally low levels of activity in either the intrinsic or the extrinsic networks leads to problems with our mental functioning and mental health. Meditation research often focuses on attenuating or augmenting function or structure in one of these networks, but typically fails to take into account any relational effect in the other network. For example, meditation and mindfulness experiments have illustrated improvement in cognitive tasks linked to meditation practice. But the increased TPN functionality may also be reducing activity in the DFN; unfortunately, this is an underresearched area.

“While more clinical and basic research is needed to establish the modulation of the DMN and TPN through meditation, and to understand the impact of modulation on ageing and mental disease, the data indicate that meditation may influence different cognitive processes, thus increasing attentional focus and cognitive flexibility.”

Ricardo Ramírez-Barrantes et al.1

Ricardo Ramírez-Barrantes and colleagues published a paper in 2019 that drew attention to the relationship between mental training and meta-awareness.1 Meta-awareness, also known as metaconsciousness or metacognitive awareness, can mediate activity across the I-ENs. That by using meditation to integrate functions in these networks, the rate of cognitive decline in middle and old age might be reduced.

Because of the limitations in meditation and mindfulness research, claims about the regulation of I-ENs through mind-training are still speculative. However, there is a good deal of data,  some presented in this paper, that suggests meditation may have an essential role in maintaining brain function and structure through the lifecycle.

Notes

1 Ramírez-Barrantes, R., Arancibia, M., Stojanova, J., Aspé-Sánchez, M., Córdova, C., & Henríquez-Ch, R. A. (2019). Default mode network, meditation, and age-associated brain changes: what can we learn from the impact of mental training on well-being as a psychotherapeutic approach?. Neural plasticity.

Memory improvements possible from meditation in middle and old age

There are strong indications that meditation and mindfulness practice may have a positive impact on dementia and cognitive decline.

man hands waiting senior
Meditation appears able to help improve memory even in people suffering from cognitive decline?

Authors: Russell-Williams, J., Jaroudi, W., Perich, T., Hoscheidt, S., El Haj, M., & Moustafa, A. A.

Year: 2018

Title: Mindfulness and meditation: treating cognitive impairment and reducing stress in dementia

Summary: Mental health concerns linked to an ageing population include, Alzheimer’s disease (AD), dementia, mild cognitive impairment and subjective cognitive decline. We should say at the outset that when people are diagnosed with early-stage dementia, increased stress levels leading to poorer health more generally may follow close behind. This notion was reflected in the aims of this review.

There is evidence that meditation technologies can boost brain function and structure, but there is a lack of research investigating the benefits to populations already suffering from declining cognitive performance. This narrative review examined ten studies that explored the benefits of meditation on dementia-related memory conditions. The study looked across a range of scientific papers to identify trends and patterns. This should not be confused with experimental replication (the repetition of experiments to confirm scientific reliability).

The reviewed studies were seeking to understand if meditation could influence the cognitive performance, quality of life and perceived stress of people already experiencing different degrees of memory-related cognitive decline. The good news is that all of the studies demonstrated significant or ‘moving towards significant’ results. Collectively, these findings indicated that meditation could lead to

  • a reduction in cognitive decline
  • an increase in functional connectivity in the brain
  • a reduction in perceived stress
  • an increase in quality of life

The bottom line is that meditation appears able to improve brain function in people already suffering cognitive decline. Observed changes are likely to be linked to structural alterations in the brain. These positive developments can, in turn, lead to reduced levels of stress and improved quality of life.

“These preliminary findings offer causes for optimism in the treatment of cognitive decline. However caution must be expressed until results have been reliably replicated.”

Stephen Gene Morris

Link: www.degruyter.com

Intelligence linked to brain size

Not a surprising headline until you consider that Dr Erhan Genç and Christoph Fraenz at Ruhr-Universität Bochum are reported as suggesting that people with higher scores on an intelligence test were found to have smaller brain structures. […]

Meditation changes brain size?
Meditation can change brain size, but not only in one direction

Not a surprising headline until you consider that Dr Erhan Genç and Christoph Fraenz at Ruhr-Universität Bochum are reported as suggesting that people with higher scores on an intelligence test were found to have smaller brain structures.

Brains are extremely complex organs and many aspects of their function and structure are not yet fully understood. However, we do know that neurons usually gather data from adjacent (presynaptic) neurons through complex tree-like structures containing many dendrites. The dendrites communicate with their own neuron’s cell body. Based on the messages received through the dendrites, a cell may fire (create an action potential) or not. When an action potential is generated, a message is then sent out to other neurons (postsynaptic) through the axon terminal. The reports of this study (I haven’t read the actual paper yet) is suggestive that people with fewer dendrites feeding into certain neurons in the cerebral cortex had higher IQ scores.

Dendrite (PSF)There are typically large numbers of dendrites communicating with each neuron in the cerebral cortex. There is a putative logic which could argue that smaller dendrite trees could be more efficient. Leading to a greater number of relevant action potentials being created more quickly. Given our limitations in understanding the mechanisms that lead to the generation and maintenance of dendrites, some caution needs to be expressed here. Without an appreciation of what the extra dendrites (in the participants with lower IQ scores) do, and why they are there, the picture is incomplete. Intelligence tests in general and IQ tests, in particular, are regarded by many experts as being reductive. It is possible that people with a history of IQ testing could have developed dendritic structures able to support this activity. But has anything been lost in the process? Are the extra dendrites in the lower IQ scored participants simply inefficient, and of no real benefit?

So what has this got to do with meditation? I wrote recently about structural changes in the brains of meditators. A conclusion from my own investigations was that increases and decreases in brain structures are likely to be the result of intense and sustained meditation practice. So the demonstration that neurological structures become bigger or smaller is probably an unhelpful oversimplification. The relationship between the alteration in structural size in different (interrelated) regions of the brain needs to be understood and then correlated to cognitive functionality if the understanding of the significance of changes is to be approached.

Rather than increasing or decreasing brain structures, meditators should probably think about their practice in terms of its deliverable goals in relation to behaviour. Brain imaging technology is still in its infancy and there are many significant problems still to overcome. We are probably decades away for being certain of the impact of complex human behaviours (like meditation) on brain structure, but we have for centuries been able to relate certain practices with behavioural changes. There are two obvious exceptions to these generalizations, age-related structural decline and changes due to neurodegeneration.

It should reiterate that I haven’t seen the full report of the Genç and Fraenz paper but a report is available at Eureka Alert.