What if it wasn’t just the act of meditating that mattered for the brain, but the way you breathe during the session? An American team has just shown that a simple change in breathing rate during meditation is accompanied by measurable variations in proteins linked to
Alzheimer’s disease in the blood.
Published in the journal Psychophysiologytheir randomized study suggests that combining a slow breathing to a mindfulness meditation brings down some blood biomarkers of Alzheimer’s, while the same meditation without breathing instructions would do the opposite. Enough to arouse a lot of curiosity.
Meditation can prevent Alzheimer’s disease
Alzheimer’s disease is characterized by the accumulation of beta amyloid plaques in the brain. These plaques are formed by the aggregation of amyloid beta peptides, proteins normally produced during cellular activity. But when these peptides are produced in large quantities or are not eliminated, they can stick together, form plaques and disrupt brain function. To prevent disease, different strategies attempt to reduce the production or accumulation of these proteins.
Previous research has suggested that meditation may reduce the risk of dementia. But which elements of this relaxation are the most important? “Slow breathing is an important part of some meditative practices, but not others.explains Mather. “We were interested in whether slow breathing during meditation reduced plasma amyloid beta levels more than meditation without slow breathing..
Slow breathing more essential than meditation alone
The researchers recruited 94 volunteers, including 89 young adults aged 18 to 35, who did not regularly practice meditation. They were randomly divided into three groups for one week: mindfulness meditation centered on the stomach with slow breathing (inhale for 5 seconds, exhale for 5 seconds, approximately 6 breaths per minute), identical meditation with natural breathing, and a control group without intervention, for 20 minutes twice a day.
Before and after the experiment, the researchers collected blood samples to analyze plasma from participants in both groups, focusing on amyloid beta peptides (specifically amyloid beta peptides 40 and 42). In healthy adults, a meta-analysis found that high levels of amyloid beta 40 and 42 in the blood are linked to an increased risk of developing Alzheimer’s disease.
The results showed that only the group practicing meditation with slow breathing saw a decrease in plasma levels of amyloid beta 40 and 42. In contrast, the group meditating without slowing breathing experienced an increase, while the control group remained stable. The researchers also measured tau proteins, another indicator of Alzheimer’s disease, but observed no significant changes in their levels or in the ratio of amyloid types. According to them, this result was predictable, because these markers generally evolve more slowly or are more relevant in older people who are already affected. Participants’ levels of stress, anxiety, or depression did not show significant changes between the different groups.
“We found that daily sessions of slow breathing intended to increase heart rate oscillations tend to decrease levels of amyloid beta in the blood.” said Mara Mather, a professor at the University of Southern California.
What happens in the body when breathing slowly
On a physiological level, breathing more slowly amplifies the natural oscillations of the heart rate between inspiration and expiration, a sign of increased activation of the parasympathetic system and the vagus nerve.
The authors hypothesize that this vagal stimulation could direct the amyloid precursor protein (APP) towards a non-amyloidogenic form, which does not produce amyloid beta.
Conversely, meditation requiring strong concentration without slowing down the breath could, in novices, increase noradrenergic activation linked to the effort of attention, which the literature rather associates with increased production of amyloid beta.
These results echo another trial, published in
Scientific Reportswhere 54 young adults and 54 older adults who practiced 5 weeks of slow breathing guided by biofeedback saw their levels of amyloid beta 40 and 42 decrease, while they increased in the control group. “Heart rate variability biofeedback may decrease amyloid beta levels in the blood“, said Mara Mather.
A promising avenue, but still very preliminary
Work is being prepared to verify whether longer protocols of slow breathing also modify amyloid beta in the cerebrospinal fluid, much closer to cerebral reality. While waiting for these data, these studies show above all that all forms of meditation do not have the same physiological profile, and that the simple choice of slowing down one’s breathing or not could be enough to orient biological markers associated with Alzheimer’s differently.
The authors nevertheless point out that a drop in amyloid beta in the blood does not automatically mean a drop in the risk of Alzheimer’s disease. Plasma biomarkers remain indirect indicators, only correlated with what is happening in the brain. In addition, the participants were young, in good health, followed over a very short period of time, without measurement of cognitive performance, which strongly limits clinical extrapolations.