The body's pH level is often stated to become slightly more acidic (below pH 7) as we age, but studies are inconsistent. Ideally, blood pH remains tightly regulated within a narrow range (around 7.4). This is crucial for many bodily functions. It's less clear how the brain's PH is modified with aging and disease. A collaborative research group comprising 131 researchers from 105 laboratories mostly from Japan has published an impressive paper in eLife on the influence of brain pH and lactate levels in neurological disorders. The research group's previous findings in a 2018 small study, suggest that the brain's PH alteration is a consequence of diseases. This conclusion was drawn from five animal models of schizophrenia/developmental disorders, bipolar disorder, and autism.

The recent study, suggests that changes in brain pH and lactate levels are a common feature in a diverse range of animal models of diseases, including schizophrenia/developmental disorders, bipolar disorder, autism, as well as models of depression, epilepsy, and Alzheimer's disease. What could be the mechanism between increased lactate and decreased pH? Lactate is a byproduct of metabolism and it is an acid, hence the acidification of pH. Neuronal activity relies heavily on glucose for energy. Under normal conditions, oxygen is readily available, and glucose is broken down through aerobic respiration, producing ATP (energy) with minimal lactate as a byproduct. However, during periods of high neuronal activity or limited oxygen supply, cells shift to anaerobic metabolism, relying more on glycolysis. This process produces more lactate as a byproduct.

These changes were observed in the postmortem brains of patients deceased of several neurological diseases, including Alzheimer's disease. However, the observed phenomena are potentially confounded by secondary factors such as the administration of antipsychotic drugs. In addition, the brains of deceased patients have undergone multiple changes during the transition between life and death, and the conservation process, and these postmortem brains may not reflect the condition of living patients.

This time the authors included autism, epilepsy, bipolar disorder, autism, models of depression, epilepsy, and Alzheimer's disease, as well as peripheral diseases or conditions comorbid with psychiatric disorders (e.g. diabetes mellitus [DM], colitis, and peripheral nerve injury). These animal models included 109 mice, rats, and chick animal models with genetic modifications, drug treatments, and other experimental manipulations such as exposure to physical and psychological stressors. More than 2200 animals were used in a hundred laboratories.

First, this large-scale animal model study revealed that alterations in brain pH/lactate levels can be found in approximately 30% of the animal models examined. 30% is not 100% so more studies are needed to understand this result.

The authors observed no significant correlation between brain pH and age in the wild-type/control rodents. In human studies, inconsistent results have been obtained regarding the correlation between brain pH and age. There isn't necessarily a direct cause-and-effect relationship between aging and altered pH, but rather a decline in the body's efficiency to maintain homeostasis (stable internal environment).

• Reduced Kidney Function: Kidneys play a key role in balancing blood pH by filtering out acids. As kidney function declines with age, the body may struggle to eliminate excess acid: Drink more, and quality water with low minerals!
• Decreased Metabolic Activity: A lower metabolic rate can lead to the buildup of acidic byproducts in the body. Decreased Metabolic Activity manifests itself in slower digestion, heart rate, and breathing, lower body temperature, and reduced strength.

So the authors conclude that if this correlation between brain pH and age, is a feature of disease and not aging, then brain diseases might be instrumental in the appearance of these changes in pH in the brain, but the mechanism of action is far from clear.

Their analysis found that poorer working memory performance in animal models of neuropsychiatric disorders may be predominantly associated with higher lactate levels, which was confirmed in an independent cohort. They found the same result for anxiety, probably because it causes a large increase in brain activity.

In conclusion, this is an excellent study, there are too few studies of that caliber. In the future research will improve the brain's ability to remove lactate. This might involve stimulating transporters that clear lactate from the CNS or potentially using enzyme therapies to convert lactate into other metabolites. Another possibility is with therapies that encourage the brain to rely more on aerobic respiration (oxygen-dependent energy production) as they could minimize lactate production as a byproduct. This could involve optimizing blood flow to the brain or exploring potential metabolic drugs.

Here is another study that announces exceptional results "A daily fiber supplement improved brain function in people over 60 in just 12 weeks!"

The scientists are raving in the press kit: "We are excited to see these changes in just 12 weeks. This holds huge promise for enhancing brain health and memory in our aging population." says first author Dr. Mary Ni Lochlainn from the Department of Twin Research.

Yet other studies have previously shown limited evidence that probiotics may improve cognition in older people with pre-existing cognitive impairment but no clear evidence of the benefit on physical function, frailty, mood, length of hospitalization, and mortality. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7515554/ Improving cognition using a simple probiotic would be an extraordinary result due to its simplicity of implementation.

In this study, as in almost all studies, we do not know what led the scientists to test the effect of a molecule. Here the authors wanted to boost the muscle mass of elderly twins (over 60 years old).

Both twins consumed a protein (BCAA) supplement powder, and in one twin from each pair, this was combined with a prebiotic supplement 7.5 g of prebiotic (Darmocare Pre®, Bonsuvan), which consists of inulin (3.375 mg) and fructo-oligosaccharides (FOS) (3,488 mg) and in the other twin from each pair, it was combined with a placebo (maltodextrin). As the products were sent by postal service, it is not known to what extent the treatment was correctly administered. Similarly, it was the patients measured by themselves their performance on the tests. The gender of the patients was not collected but it is assumed as they were elderly patients, that the cohort is majority female.

Stool samples were collected by the participants themselves using the sample collection kits provided. Twins were asked to collect a “pea-sized” stool sample into a DNA/RNA Shield Faecal Collection Tube (Zymo Research), and these were posted to the laboratory.

There is a strong recruitment bias (as usual): Participants were eligible for inclusion if they were aged 60 years or older and had previously reported low dietary protein intake (<1 g/kg body weight/day).

However, when we look at the results, it seems they are very different from what is advertised (as usual).

The results are generally the same in the two groups, with even an improvement in the chair rise test, contrary to what is announced. This improvement is even greater in the placebo group! Could this be attributed to the administration of maltodextrin in the placebo group?

Reviews have concluded that digestion-resistant maltodextrin is classified as a type 5 resistant starch (RS5), a prebiotic dietary fiber having properties that may improve the management of diabetes and other disorders of metabolic syndrome. The action of maltodextrin could be quite similar to that of the BCAAs used in the treatment group.

For the CANTAB test, there is improvement in both groups, but the improvement is greater in the treatment group. However, a standard deviation of 0.83 indicates that the results were indeed highly variable from one patient to the next, highlighting the heterogeneity of responses within the study population.

Furthermore, at the start of the study, the treatment group did not seem to be already impacted by cognitive problems while this was already the case for the placebo group, which raises questions about the objectivity of the random distribution between the two groups.

• For the latency test (response speed) both groups progressed, but the treatment group progressed more.

• For the Spatial working memory test, it is the placebo group that progresses the most!

• For the PAL test: first attempt memory score, it is the treatment group which progresses the most (but as for the previous test both groups progress)

• For the Pattern recognition memory test, both groups progressed, but the treatment group progressed more.

• For the Spatial span (forward span length) test, the treatment group progressed, but the placebo group regressed.

In conclusion, the study announces exceptional results, but the results are minimal, and above all, they may be because the investigators supplemented a group of patients who had been selected as being undernourished with protein. Both groups received compounds that are sugars in the broad sense.

Here is a quick analysis of two recently published papers. One is about the controversial role of 40Hz signals in Parkinson's and Alzheimer's disease, the other is about brain clearance during sleep. Intriguing connections suggest that VIP signaling pathways and EEG activity patterns may contribute to the regulation of brain waste clearance mechanisms during sleep. Indeed further research is needed to explore these interactions comprehensively. The first text discusses the paradoxical activity observed in the brain during sleep, where the brain remains highly active despite the body's restful state.

Scientists from Washington University School of Medicine in St. Louis have discovered that during sleep, brain waves play a crucial role in flushing waste out of the brain. These brain waves, generated by coordinated neural activity, facilitate the movement of fluid through dense brain tissue, effectively cleansing it.

The research indicates that sleep serves as a critical time for the brain to initiate a cleaning process, eliminating metabolic waste and toxins that accumulate during wakefulness. This cleansing mechanism is essential for preventing neurological diseases such as Alzheimer's and Parkinson's, where excess waste buildup leads to neurodegeneration.

The authors demonstrated that neural networks synchronize individual action potentials to create large amplitude, rhythmic, and self-perpetuating ionic waves in the interstitial fluid of the brain. These waves are a plausible mechanism to explain the correlated potentiation of the glymphatic flow through the brain parenchyma. To demonstrate that the scientists showed that flattening these high-energy ionic waves largely impeded cerebrospinal fluid infiltration into and clearance of molecules from the brain parenchyma. Notably, synthesized waves generated through transcranial stimulation substantially potentiated cerebrospinal fluid-to-interstitial fluid perfusion. So their study demonstrates that neurons serve as master organizers for brain clearance.

This reminds us of the "40hz" publications that many scientists find controversial.

Funnily another article is published by some of the MIT scientists who told a few years ago that gamma stimulation at a frequency of 40 Hz can reduce Alzheimer's disease progression. The authors of The Picower Institute for Learning and Memory of MIT have now discovered that this stimulation prompts a specific type of neuron to release peptides, which in turn drive processes promoting amyloid clearance via the brain's glymphatic system. This mechanism suggests a potential avenue for treating neurological disorders through sensory stimulation.

The authors from MIT say the relation between the 40hz signals and brain clearance is through interneurons in the brain that express the VIP protein. While named Vasoactive Intestinal Peptide (VIP) because it is first was found to be an intestinal peptide that influences blood pressure and heart rate, it is also expressed in other tissues such as the brain's cortex and hypothalamus.

Brain Clearance and VIP

Vasoactive Intestinal Peptide (VIP) plays a role in modulating various physiological functions in the brain, including neurotransmission and circadian rhythm regulation. Similarly to its action in the intestine on heart and blood flow, studies suggest that VIP is involved in the regulation of cerebral blood flow and may have implications for brain waste clearance mechanisms.

VIP and EEG Brain Waves

VIP-expressing neurons are involved in the regulation of circadian rhythms and are particularly abundant in the suprachiasmatic nucleus (SCN) in the hypothalamus. The SCN exhibits rhythmic electrical activity, which influences sleep-wake cycles and may indirectly affect EEG brain wave patterns during sleep. So VIP-mediated signaling pathways may intersect with mechanisms regulating EEG brain waves and brain clearance processes during sleep. VIP's role in modulating neural activity and circadian rhythms may influence the generation of EEG patterns associated with sleep stages, which, in turn, could impact glymphatic clearance and waste removal in the brain.

As usual, don't expect fast progress if this therapy hits the market, months of chronic sensory gamma stimulation may be needed to have sustained effects on cognition.

This post is about an interesting hypothesis. Hypotheses abound, yet few a convincing.

Half of patients with Alzheimer's disease, Parkinson's disease, or ALS have insulin resistance. Obesity and diabetes have been linked to neurodegenerative diseases like multiple sclerosis (MS), Alzheimer's (AD), and Parkinson's (PD). This means the cells of their body cannot let the glucose enter them. Glucose is the main energy source as it is converted into ATP. Glucose is for short-term (day) energy needs. Another source of energy is lipids (fat). Lipids are even more dense than glucose energy-wise.

The body needs an enormous amount of energy. With all the lipids in the body of a healthy person, you could charge two Tesla cars! The brain (a part of the CNS) needs 20% of all energy intake.

A new paper argues that cells shift their metabolism from glucose to lipids under stressors. It tells that one notable distinction between glucose and lipid metabolism is in the quantity of oxygen required to generate each ATP molecule. Lipid metabolism needs two times more oxygen than glucose metabolism. The result is two times more damaging ROS (a by-product of metabolism). Studies have shown that oxidative stress and endoplasmic reticulum stress are correlated and can lead to protein misfolding (Abramov et al., 2020). Accumulation of misfolded proteins causes cellular damage and mitochondrial dysfunction and is associated with a range of neurodegenerative diseases, including ALS (misfolded SOD1, TDP-43, C9orf72) (McAlary et al., 2020), Parkinson's disease (misfolded α-synuclein) and Alzheimer disease (misfolded Aβ and Tau) (Abramov et al., 2020).

It explains also the accumulation of iron in patients' brains: To transport oxygen the blood cells need iron, and as the glucose in the blood is not absorbed in cells, it induces a change in microbiota.

It's also well known that SCFAs (including butyrate) have a positive effect on neurodegenerative diseases by their action on microbiota. SCFAs help to restore glucose as the preferred energy substrate. Authors say there are other means to restore glucose as the main source of energy.

What to think about this paper? First, some authors belong to a biotech so we can expect they want to promote their drug: Mitometin. Second, this is a review, this is not even a pre-clinical study, yet some of the authors were involved in pre-clinical studies on this topic. Other groups have written on this topic. What to make of this? Acetyl-CoA carboxylase might be of interest as they produce malonyl-CoA which inhibits the CPT1 gene that regulates lipid metabolism. B7 vitamin is known to convert acetyl-CoA to malonyl-CoA for fatty acid synthesis.

Scientists are never short of new hypotheses about the cause and even the nature of diseases. For example, some of them now believe that “inflammation” is the underlying cause of many neurodegenerative diseases.

The human immune system is made up of different subsets of extreme complexity. The main mode of action is quite brutal, as the cells renew themselves quite quickly (from a few days to a few weeks), any slightly suspicious cell is deliberately killed by one of the agents of the immune system.

The central nervous system is composed of cells that have a probable lifespan of a hundred years or more, and they do not renew themselves through division, so this mode of operation is impossible. Therefore the central nervous system is kept isolated from the rest of the body through the blood-brain barrier and it has its own immune system.

Breaks in this barrier and the invasion of the CNS by the body's immune cells have sometimes been suggested as being able to cause diseases such as ALS, and now Alzheimer's. A new article aims to show that in the case of Zika viruses, the terrible consequences that an infection causes are not due to the infection of cells by the virus, but by the invasion of the CNS by immune cells from the rest of the body.

The article incriminates CD8+ T cells which function like NK cells, formidable killers.

Antibody depletion of CD8 or blockade of NKG2D prevented ZIKV-associated paralysis.

Of course, this article is based on an experiment with mouse models of a disease, so it is quite risky to draw conclusions for humans.

In any case, once the damage is done, it is too late, as the neurons do not reproduce. Yet it is possible to have a form of damage mitigation, either thanks to neurogenesis in certain rare cases, or even to a sort of mutual aid mechanism between neurons, which causes a surviving neuron to try to take over the work of the dead neurons. This is what causes us to become clumsy as we age.

Therapy is therefore not to be expected quickly, the best is to maintain a healthy blood-brain barrier, that is to say, to follow the precautions recommended for cardiovascular diseases.

The TCA cycle (Krebs cycle) is the primary mechanism for ATP synthesis in brain cells, operating within the mitochondria's matrix. Additionally, glycolysis contributes to ATP production, particularly during heightened energy demands or glucose scarcity. Insulin plays a crucial role in regulating glucose metabolism and maintaining neuronal function.

Mitochondria, akin to tiny microbe-like structures, are strategically located within cells to provide energy where needed, including neuronal terminals. Synthesized primarily in the soma, the central part of the neuron, mitochondria must undergo transport to distant neuronal terminals. Maintenance of mitochondrial health is crucial as damaged mitochondria can induce oxidative stress, necessitating fusion with healthy counterparts for repair or elimination. Thus, ensuring mitochondrial integrity is paramount for neuronal function.

In both processes -glycolysis and the citric acid cycle- during oxidative phosphorylation (OXPHOS) glucose and other substrates are metabolized, generating the synthesis of ATP.

A new text using the detrimental effects of S-nitrosylation on TCA cycle function, provides insights into potential therapeutic interventions.

The scientists compared in-vitro isogenic wild-type and Alzheimer's disease mutant human induced pluripotent stem cell (hiPSC)-derived cerebrocortical neurons (hiN) and found evidence of dysfunctional processes in mitochondria. This aberrant S-nitrosylation is documented not only in hiN cells but also in postmortem human Alzheimer's disease brains versus controls

Detailed analyses showed significant inhibition of metabolic flux at various steps of the TCA cycle in hiN. It suggests that deficiencies in TCA cycle function were associated with a shift towards compensatory glycolysis, suggesting an adaptive response to impaired oxidative phosphorylation. In particular, supplementation with dimethyl succinate, a substrate bypassing the inhibited step in the TCA cycle, suggests a potential therapeutic strategy to mitigate mitochondrial dysfunction in Alzheimer's disease. Dimethyl succinate (DMS), a membrane-permeant form of succinate, could serve as a pro-drug to provide substrate to the next enzymatic step in the TCA cycle, succinate dehydrogenase (SDH).

Those findings are not entirely surprising and the motivation of the scientists seems more to test a new mass spectroscopy technique than finding a drug. Anyway, it may add to the incentive to make pre-clinical trials of dimethyl succinate in rat Alzheimer's disease models.

Usually, Dimethyl succinate is sometimes used as a solvent. Yet dimethyl succinate is an irritant and an explosive product.

Unfortunately, after decades of research and hundreds of unsuccessful phase III clinical trials, it's clear that the pharmacological industry and a cohort of academic laboratories are unable to create drugs that slow significantly the progression of neurodegenerative diseases.

Some courageous scientists interrogate basic hypotheses or design longer, more complex better clinical trials. For example, Alzheimer's disease can't seriously be attributed to any molecular dysfunction, as it would mean that a lot of cerebral functions would be affected, not only memory issues, and anyway, memory issues in Alzheimer's are much more complex than described in textbooks: They did not simply vanish: The patient looks to be living today in the context of the past. Sometimes the patient can discuss simultaneously at two levels: In the context of the past (when they were infants) and in the context of today.

Others are currently busy breaking the thermometer. If the clinical diagnosis makes it impossible to validate current clinical trials, then change the way success is defined: Abandon clinical criteria and use molecular criteria. They did it recently for Alzheimer's disease and now they propose it for Parkinson's disease..

The immediate consequence will be a flurry of successful clinical trials, even if patients get no improvements, as they did for Aducanumab.

There will also be false positives, people will be diagnosed sick because of the presence of a molecule but without any clinical signs.

Quelques jours avant que mon père décède, j'ai demandé à son médecin quelles pouvaient être les actions médicales à mener pour améliorer son état. Le médecin m'a répondu "si on arrive à améliorer ses constantes, il ira mieux".

Outre le fait que le médecin ne me répondait pas vraiment en terme d'actions à mener, cette lapalissade enseigne quelque chose de fondamental au sujet de l'approche de la santé par la médecine.

Les médecins sont conscients qu'en fait ils ne peuvent peuvent pas vraiment soigner, ils ne peuvent qu'améliorer un dysfonctionnement d'un corps qui autrement doit être en bonne santé. Ce corps, si on l'aide, va retrouver sa bonne santé.

Au contraire, une personne atteinte de comorbiditées a une chance de survie très faible, c'est de la statistique élémentaire. Si un malade a trois problèmes de santé ayant chacun une chance de survie de l'ordre de 80%, la résultante n'est que de 51%. Il est donc illusoire de penser que quand la physiologie est sévèrement compromise, on pourra restituer la santé avec une pilule ou une injection miracle.

Cette limitation de la médecine actuelle, n'est pas compris par les scientifiques. Ceux-ci s'obstinent à penser qu'en agissant sur une composante infinitésimale de notre physiologie, la santé sera, comme par magie, restituée. Cet aveuglement s'explique par le fait que la quasi totalité des scientifiques oeuvrant dans la recherche médicale, n'ont qu'une notion vague de la physiologie humaine et des interactions entre ses multiples systèmes.

Cela explique pourquoi je ne présente pas les multiples articles qui apparaissent tous les jours et qui annoncent une découverte majeure, alors que le plus souvent il s'agit de travaux mineures sur une souris, ou pire encore sur une lignée de cellules dénaturées immortelles.

Outre le fait qu'un scientifique doit publier pour être crédible, et donc qu'on a une avalanche de papiers au style ampoulé mais sans valeur, beaucoup se demandent pourquoi les souris semblent si bien répondre aux traitements, alors que quand ces traitements sont testés sur des humains, ils échouent à améliorer l'état des malades.

La réponse est complexe, mais un point essentiel est celui-ci: La tenue de l'expérience est soit confiée à des étudiants (masters, doctorants), des salariés (postdocs) ou à un organisme de sous-traitance de la recherche (CRO). Dans ces différents cas de figure, les personnes à qui sont confiées ces souris ont intérêt à ce que l'hypothèse faite par le professeur donneur d'ordre soit avérée. or on sait que la santé d'une souris est fortement dépendante à des caresses ou à un nettoyage de la litière (ce qui d'ailleurs influence le microbiome intestinal)...

La moralité de tout ceci est que pour un patient il faut essayer de faire fonctionner normalement son corps et son esprit autant que possible: Conserver une certaine activité physique, conserver une activité intellectuelle, s'informer à des sources fiables, avoir une sécurité financière, combattre les problèmes cardio-vasculaires, notamment l'hypertension artérielle, et lutter contre le diabète notamment en limitant la plage horaire où l'on ingère de la nourriture, conserver des contact sociaux notamment parce que celà oblige à faire attention à soit-même, combattre le tabagisme et dormir convenablement.

Cela est plus facile à écrire qu'à mettre en oeuvre.