Migraine: What the science says

2023-11-23 12:05:34

Migraine triggers can include food, environmental factors (heat, atmospheric pressure), stress, emotions, lack of sleep, dehydration, etc. Specific to each individual, they can also vary from one attack to another. But we don’t really know how they act. What is certain : the attack starts with a sudden electrical disturbance, probably in the hypothalamus. This small brain structure integrates information coming from the outside and is involved in sleep cycles, hormonal secretion and pain modulation pathways…

An electrical disturbance

Neuroimaging shows the activation of numerous brain areas, linked to the different symptoms, before (premonitory phase), during (painful phase) and after the attack (postdromal phase). Most likely hypothesis: nerve endings, abnormally excited, release an excess of neuropeptide, CGRP (peptide linked to the calcitonin gene), with effects vasodilators and inflammatory.

In response, the trigemino-vascular complex, connected to the meninges and the trigeminal nerve, is activated. It is linked to vision, taste, smell and facial motor skills. In case of migraine with aura, imaging reveals, before the headache, that neurons in the cortex activate then turn off. This depolarization spreads like a wave in the brain, lasting on average an hour, the areas crossed explaining the different symptoms of the aura. The migraine brain could have a cerebral plumbing problem; MRI reveals, alongside abnormalities in the white matter, enlarged perivascular spaces. This could suggest a dysfunction of the glymphatic system, whose function is to drain cerebrospinal fluid into the brain and evacuate waste from the nervous system.

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The genetic trail is of course being explored because there are entire families of migraine sufferers! Research has identified genetic abnormalities in the ion channels of neurons, which would explain their “ overexcitement “. Others suggest aberrant DNA methylation in the gene that codes for CGRP, linked to the appearance of migraines. Genes regulating the biological clock would also be involved.s: 50% to 70% of patients have attacks mostly during the day, in spring and fall.

A women’s disease?

Migraineurs have higher concentrations of CGRP (peptide linked to the calcitonin gene) in their tears than non-migraineurs. And this rate increases during menstruation, confirming the well-known link between migraines and estrogen fluctuations during the cycle. But it is also higher in migraineurs taking oral contraceptives or in menopause (who therefore no longer experience estrogen fluctuations), which suggests the existence of other factors…

Migraines and intestines

LThe role of the microbiota also seems very important. “ We found that in people with altered microbiota, the prevalence of migraine increased twofold. Some 40% of patients with microbiota alterations experience migraines “, notes the Professor Radhouane Dallel, director of the Neuro-Dol laboratory (Inserm-Université Clermont-Auvergne). We know that the microbiota plays an important role in the metabolism of tryptophan, an amino acid very present in food. Under the influence of certain intestinal bacteria, tryptophan is transformed into various molecules, including serotonin, a neurotransmitter essential for brain function. “ Through laboratory experiments, we have shown [chez l’animal, NDLR] that by disrupting tryptophan metabolism, we aggravate the migraine attack and reduce the effectiveness of treatments “, illustrates the professor. This involvement of the microbiota opens up avenues of treatment for a disease whose precise causes remain uncertain. Thus, a small randomized study against placebo had already shown in 2019 that 14 probiotic strains administered for eight to ten weeks reduced by 45% the frequency of migraine attacks.

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Migraine, histamine et enzyme DAO…

Histamine is a compound naturally produced by the immune system, in cases of allergies and also to regulate brain activity… but many foods contain it. Can foods high in histamine trigger migraines? It’s not so clear: antihistamines have no effect on migraine attacks, and recent findings suggest that low doses of histamine may instead prevent attacks. However, there is a real intolerance to histamine (histaminosis), which is often associated with a migraine condition. According to a Spanish team, which carried out a study on 100 patients, it could be linked to a deficiency in diamine oxidase (DAO), an enzyme present in the intestine and responsible for breaking down excess histamine. After one month of DAO supplementation, the duration of patients’ headaches was significantly reduced.

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