Israel Sánchez/ Agencia Reforma
jueves, 13 april 2023 | 06:39
Mexico City.- If in the collective conscience, Alzheimer’s persists like a disease linked to the brain, the causes of its development seem to be traced back to a place that few would imagine: the intestine.
The least of which is rooted in it, such as the intestinal microbiota, that set of microorganisms with which we subsist in a symbiotic way, and whose link with the brain is investigated by scientists who study the origin of this neurodegenerative disorder.
Such is the case of the neuroscientific Claudia Pérez Cruz (Mexico City, 1976), who even admits that such an association may sound paradoxical and anti-dogmatic, points out that it has already been seen that the brain is not impermeable nor as hermetic as it was believed, this time changes have been found in the microbiota of patients with Alzheimer’s.
Specifically, reports the researcher from the Department of Pharmacología del Cinvestav, a group in Italy that has been suffering for a few years from this pathology that generates dementia has a type of pro-inflammatory bacteria, whose presence in the body promotes the release of cytokines as part of a Aggressive potentially harmful immune response.
This is relevant, because among the causes of Alzheimer’s the accumulation of two proteins -the beta amyloid and the tau proteins- has been studied, it is clear that the disease is also accompanied by an inflammation in the brain from very early stages.
“Then, the idea arose: if we have an inflammatory environment due to the bacteria of the intestine, which eventually want to move to the brain, this would cause inflammation and lead to all protein changes, and generate damage to cognition”, elaborates Pérez Cruz in phone interview.
In addition to this, continues the researcher, something interesting is that metabolic alterations such as diabetes and obesity are risk factors for the development of this disease, from which the Health Department reports about a million 300 thousand patients in Mexico. Although it is predicted that there will be an increase in its incidence in the coming years.
“As everything becomes linked: metabolism -diabetes and obesity, which are metabolic diseases-; microbiota, which depends on the diet. So, try to link both concepts together. If we eat healthy food and change the microbiota, there will be some benefit en el cerebro?”, he planted himself.
That’s how he started a study with transgenic rats, that is, genetically modified to develop Alzheimer’s, to which they provided a specific diet to change the state of their microbiota.
“We saw that the pro-inflammatory microbiota was radically reduced, communities of anti-inflammatory bacteria began to grow.
“So, this first premise is being fulfilled: If we can modulate the microbiota, then we can prevent the bacteria from releasing harmful substances, and eventually prevent this from reaching the brain”, points out Pérez Cruz.
Deciphering the prevalence in women
Next in the investigation, and thinking that the women are more diagnosed with this disease, since today the full knowledge of the biological mechanisms that underlie this greater vulnerability was carried out, it was necessary to carry out a protocol with rats of females.
“If there is much proposed, by many research groups, that perhaps this lack of estrogens that happens when we enter menopause could be linked with the dysfunction at the level of the brain”, points out the neuroscientific.
The role of estrogen became fundamental in carrying out the protocol with female rats, with those who had to take into account the so-called estrous cycle -the set of physiological events that took place between a cycle or estrus and the following one-, which was altered to supply the diet to modulate the microbiota.
“And it was like: What do you have to do with the diet and the estrous cycle?”, the question arose among researchers, who wanted to inquire about the concept of stroboloma, the capacity of some intestinal bacteria that express an enzyme to metabolize the estrogen destined to descharse the body, and thus increase its concentration in the blood.
“We’re already desechando, but these bacteria say: ‘No, wait, let this group quit and I’ll send the hormone back to circulation'”, illustrates Pérez Cruz. “So, if we have a lot of these bacteria, increase the estrogen levels; if we have few, bajan, because it is excreted”.
This seems to be observed by researchers with female rats, whose estrogen levels increased through a diet rich in fructans, which led to positive behavioral changes. “I never expected that the diet with fiber modulate the estrous cycle”, acknowledges the neuroscientific.
In the end, this is the guideline on the preventive impact that a microbiota modulated by a certain diet, but the optimal levels of estrogen, could have in women.
“If this could happen to women, we could prevent this decline in estrogens that happens in menopause, which is something normal, it’s something physiological that we all have to go through and therefore it will give us all Alzheimer’s. But perhaps in some women when they don’t have so many of these bacteria, which is the steepest estrogen decline, and so does not protect the brain.
“Because estrogen is a hormone that we use a lot for good communication between the neurons”, he explains. “If it hurts too much, then it could be that we leave our brain very vulnerable in this period (from transition to menopause) which is from five to seven years”.
This is how a clinical study emerged in collaboration between Cinvestav and the national institutes of Medical Sciences and Nutrition, as well as Neurology and Neurosurgery, with the objective of determining the relationship between the microbiota, the levels of sexual hormones and cognitive deterioration in women, currently in development and open to those who wish to participate.
According to Pérez Cruz, volunteers from 30 to 65 years old in perimenopausal, premenopausal and menopausal or postmenopausal periods are recruited, to compare their conditions with those of women with Alzheimer’s, as well as with a control group without alterations related to estrogen, it is decided , cognitively healthy men aged 30 to 60 years
“We want to see how your microbiota is in relation to the levels of hormones, and how is the relationship between hormones and the microbiota with your cognitive function”, says the Cinvestav researcher about the protocol that includes taking a blood sample, body and have a tomography for some of the participants.
“So, we are doing cognitive tests to see if there is a relationship between the type of bacteria we have, the amount of estrogen and progesterone, and our (brain) function”, he adds. “We want to try to understand if this really is if it is (s) as in the rats, which could be linked to the presence of these bacteria that have the enzyme that regulates estrogen”.
Those interested in participating in this study, from which Pérez Cruz estimates that the first results will tend towards the third quarter of this year, can consult the requirements and answer a brief questionnaire on this site www.estroboloma.cinvestav.mx.
Participate in the studio and receive advice
In addition to contributing to science for the understanding of an illness such as Alzheimer’s, those who participate in the “Study of the dysfunction of stroboloma during perimenopause as an associated factor for the development of dementia” can have access to its results and know, for example , your hormonal profile and the state of your microbiota.
And with this you also have some recommendations on how to improve it if, for example, it is above the normal parameters of a microbiota that is considered pro-inflammatory.
Asked about what kind of food to follow to counteract this, Claudia Pérez Cruz tells that with rats a diet with functional foods was followed, that is to say, those that do not only nourish but have bioactive compounds.
“For example, the chia seed, which in addition to having essential oil and proteins, has these bioactive compounds, such as genistein, antioxidants.
“Les we say fructans, which are soluble fiber that in this case we take from the bunch of agave tequilero, and it is fiber like the one that has the nopal, like the one that would tend, for example, the garlic and the onion”, añade.
A type of food, neuroscientific explains, of which the organism does not benefit directly by consuming them, but the intention is that they are used by the bacteria; “we are feeding the bacteria, a type of bacteria that are good for us”.
“So, if there is a deficit of this type of bacteria, and we give this fiber, it starts to grow, to reproduce, to be more abundant. And that’s not just it, but they start to compete for space, land and food with those who are bad , say, and empiezan a disminuir las malas o proinflamatorias.
“This type of recommendation would be available to people who see a microbiota that is not optimal”, he adds.
