Autism and intestinal bacteria
Autism spectrum disorder is a broad diagnostic term, including the whole spectrum from severe autism to high-functioning Asperger's syndrome. The similarity of these diagnoses lies in that patients show three problems: the decline of language ability, social obstacles and repeated stereotyped behavior. Even self-harm is common. Autistic people may slap their faces or bite their hands when they are stressed or happy. Patients with mild autism, such as those with Asperger's syndrome, can have relatively normal conversations, so they are considered normal, even highly functional, but they still find it difficult to understand and use nonverbal communication, such as gestures, facial expressions and eye contact.
Autism is usually associated with children, even if it lasts for a lifetime, because it can only be diagnosed if it shows obvious symptoms of autism before the age of three. In the past two or three decades, the incidence of autism has increased rapidly, and now it is estimated that 1 person in every 68 children has autism. This disease is more common in boys, and the number of confirmed cases is four times that of girls.
What causes autism? Why is the incidence rising so fast? Previously, people thought that heredity played a great role in autism; In addition to genetics, researchers have also studied the destruction of the immune system, inflammation and the effects of environmental toxins. In recent years, more and more studies have regarded intestinal bacteria as one of the most popular candidate factors to solve the mystery of autism, and pushed it to the forefront of research.
The intestinal flora is established in the first three years of life, and it is basically close to the adult level by the age of three. Similarly, the symptoms of autism usually appear before the age of three, that is, in recent years, the brain development of autistic children began to show obvious differences, some of which developed rapidly and some developed slowly. In other words, the time window for the establishment of intestinal flora coincides with the occurrence time of autism. Now we have made it clear that intestinal flora is the decisive factor of brain development, so more and more researchers begin to think that the development of intestinal flora in the first three years of life plays an important role in the occurrence of autism. The most telling thing is the experiment of sterile mice, where the brain shrinks and develops abnormally. When sterile mice are transferred to a normal environment full of bacteria and raised with other normal mice, they will get fecal bacteria from normal mice, bacteria from the environment, restore normal intestinal flora, and their anti-social behavior will return to normal. This can not help but remind people of the antisocial behavior of autistic patients, and also fully shows that intestinal flora may play a role in autism-like behavior.
Autism is usually related to gastrointestinal problems, including flatulence, diarrhea, stomachache or constipation, among which constipation is a common symptom in autistic children. Gastrointestinal problems are very common in autistic patients, so they are classified as symptoms of autism, which is why more and more scientists believe that the interruption of dialogue between the intestine and the brain is related to autism.
In recent years, the number of studies on the relationship between autism and intestinal flora has soared, so what have these studies revealed? First of all, there is a clear connection between abnormal intestinal flora and abnormal brain development; Secondly, various studies show that the intestinal flora of autistic patients is obviously different from that of normal children; Third, preliminary research shows that improving the treatment of intestinal flora can even improve the symptoms of autism, which brings hope to parents of autistic children.
Epidemiological investigation shows that the risk of autism in children with caesarean section is higher than that in children with vaginal delivery. So far, no one really knows the reason, but more and more scientists are beginning to believe that this is related to the fact that children who have caesarean section can't get enough beneficial bacteria from their mothers' birth canal. The early intestinal flora of children with vaginal delivery mainly comes from the mother's vaginal flora, and beneficial bacteria are dominant, including Lactobacillus and Przewalskii. The intestinal flora of children born by caesarean section mainly comes from the mother's skin, such as Staphylococcus, Corynebacterium and Propionibacterium.
We also need to pay attention to the way the baby is fed after birth, and suggest breastfeeding instead of formula milk, because breastfeeding is related to the normal development of the baby's brain. Babies who are fed formula milk powder after caesarean section will have worse intestinal flora, which is related to the higher risk of autism. But if breastfeeding lasts for more than six months, the risk of autism will be reduced. Breast milk contains some probiotics and a variety of breast milk oligosaccharides that promote the growth of beneficial bacteria. Although infant milk powder manufacturers have added prebiotics and probiotics to the formula, they still cannot completely replace breast milk. Other factors affecting children's intestinal flora include stress, children's diet and living environment.
Faecal bacteria transplantation, that is, transplanting faecal bacteria from healthy people into patients' intestines, has also been used in experiments of autistic children. Firstly, the diseased intestinal flora was removed by antibiotics, and then the intestinal flora of healthy donors was reintroduced. In 20 17 years, fecal bacteria transplantation experiment was carried out in 7- 17-year-old autistic children. They took antibiotics 14 days, then fasted 12-24 hours, and then reintroduced the intestinal flora of healthy donors. At the same time, they are required to supplement low-dose probiotics for 7-8 weeks to maintain new intestinal flora. After 8 weeks, the healthy intestinal flora was successfully introduced, and the intestinal flora of autistic children had a positive change. The diversity of intestinal bacteria has increased, and the number of beneficial bacteria such as Bifidobacterium and Przewalskii has also increased. These children's gastrointestinal problems such as constipation, diarrhea and stomachache have also been drastically reduced by 80%; Similarly, typical autism behaviors and symptoms also improved after treatment. Most importantly, this benefit seems to last at least two years after treatment.
Since fecal bacteria transplantation can alleviate the symptoms of autism in children, can taking probiotics through diet or supplements also improve serious neuropsychiatric diseases such as autism? The answer seems to be yes. Some studies have investigated the role of probiotics in autism. In different studies, the exact combination of probiotics is different, and the familiar Bifidobacterium and Lactobacillus are usually used. Among the reported results, the following points are worth mentioning: reducing harmful Clostridium, improving intestinal function, reducing anxiety, reducing anti-social behavior, reducing communication difficulties, improving attention and ability to obey orders, and so on.
A prospective open-label clinical study of 20 17 in Egypt found that after three months of intervention by compound probiotics consisting of Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium longum, the expression/language communication ability, social ability and perception/cognition ability of autistic children were significantly improved, and the symptoms such as constipation, stool characteristics, flatulence and abdominal pain were also significantly improved.
Recently, the research team of Qilu Children's Hospital of Shandong University found that the intervention of probiotics (Bifidobacterium infantis, Lactobacillus rhamnosus, Bifidobacterium lactis and lactobacillus paracasei) and fructooligosaccharides can significantly improve autism and gastrointestinal symptoms of autistic children, increase beneficial bacteria in the intestines of autistic children, reduce harmful bacteria such as Clostridium and restore the level of short-chain fatty acids.
Studies have shown that the diversity of intestinal bacteria in children treated with antibiotics before the age of three is significantly reduced. This is not surprising because we know that antibiotics can kill both beneficial bacteria and harmful bacteria.
Because diversity is a sign of healthy intestinal flora, it is also a prerequisite for a strong immune system and brain health, which is not good news for children who have received too many unnecessary antibiotics. Remember, a person's intestinal flora was established in the first three years, which is a critical period when the development of intestinal flora is closely related to the development of the brain. A study based on a large population shows that the intake of antibiotics by mothers during pregnancy will affect the intestinal flora of newborns, thus increasing the risk of autism in children. However, antibiotics do not always have negative effects. They have been proved to improve gastrointestinal problems (such as diarrhea) or autism behavior in a short time, which may be because antibiotics destroy pathogenic bacteria in the intestine. In other words, antibiotics are a double-edged sword for autism. Antibiotics can kill harmful bacteria in the intestine, which may temporarily relieve the symptoms of autism, but long-term use may cause more serious damage to the intestinal flora, and may lead to the recurrence or even deterioration of symptoms. However, this information tells us that the composition of intestinal bacteria plays a central role in autism, and regulating intestinal flora is helpful to improve the symptoms of autism.
ADHD and intestinal bacteria
ADHD is the most common neuropsychiatric disease in the world, which usually begins at school age. About 30-50% of children diagnosed with ADHD still maintain this diagnosis after adulthood. In the past few years, the number of people diagnosed with ADHD has increased dramatically. Many people think that this may not really increase, but because of newly discovered diagnostic methods, which may have been missed before. Others believe that this increase is too high to be attributed to new diagnostic methods alone. There are also some people who think that ADHD is a feature of the nervous system, not an obstacle. People with ADHD are not suitable for the sedentary lifestyle in modern society. This is why ADHD is usually regarded as a personality trait, not a disorder.
What is ADHD? It stands for attention deficit/hyperactivity disorder and includes three core features: inattention, impulsiveness and hyperactivity. ADHD children's inattention will lead to learning problems, poor academic performance and even aggressive behavior. ADHD is generally considered to be related to the disorder of dopamine and norepinephrine, which are important for attention and impulse control. In ADHD patients, the genes that control these neurotransmitters in the brain are also different. When it comes to the connection with intestinal flora, compared with autism, there is much less research in this area.
Like autism, ADHD is accompanied by gastrointestinal problems and increased inflammation in the blood. Most people with ADHD also suffer from gastrointestinal diseases, which makes the symptoms more serious. A large-scale study of 742,939 children showed that the incidence of constipation in children with ADHD was higher. Studies have also shown that inflammatory products are more common in the blood of children with ADHD. We know that gastrointestinal dysfunction and intestinal flora imbalance will make the body and brain more prone to inflammation. A few studies have found that the intestinal flora composition of ADHD patients is different from that of healthy people. This different intestinal flora may affect the production of dopamine and thus hinder the reward response.
At present, karolinska institutet, Sweden is conducting a research on ADHD. First, researchers are investigating whether using antibiotics in the first few years after birth will increase the risk of ADHD. We know that children's intestinal flora is particularly fragile, and excessive use of antibiotics will destroy intestinal flora, which may lead to ADHD. Secondly, researchers are investigating whether bacterial products that promote inflammation will enter the blood of ADHD children through the intestine, because we know that inflammatory products are more common in the blood of ADHD children. Third, researchers are investigating whether regulating intestinal flora can improve the symptoms of ADHD children.
Although there is not enough evidence to prove that unhealthy intestinal flora can lead to ADHD, healthy intestinal flora may be a protective factor for ADHD genetic susceptibility. As we have seen, probiotics can greatly improve the symptoms of autism, so it may also alleviate ADHD by improving intestinal health and mental symptoms. Probiotics can be used as an effective supplement to other methods to treat ADHD.
Neuropsychiatric diseases are serious problems that plague every stage of our lives. Autism and ADHD in childhood, depression and anxiety in adolescence and adulthood, Alzheimer's disease and Parkinson's disease in old age, all of us may be affected. At present, there is no effective treatment for these diseases, and more and more studies are revealing the role of intestinal flora in brain function and behavior. These breakthrough studies are completely changing our views on neuropsychiatric diseases and providing new hope for the treatment of these diseases.
The pictures are all from the Internet.
References:
Soki Choi。 Kombucha and Kimchi: How Probiotics and Prebiotics Improve Brain Function. Tianma publishing house, 20 18.