很多自閉症患者有廣泛使用抗生素病史。口服抗生素顯著破壞保護性腸道微生物群，為趁虛而入的病原體創造有利環境。破傷風梭菌是一種普遍存在的的厭氧桿菌，可產生強力的神經毒素(TeNT)。迷走神經能夠將破傷風毒素由腸道運送至中樞神經系統。一旦進入大腦，TeNT破壞了神經遞質的釋放(見下圖)......這種對神經遞質釋放的抑制可以解釋自閉症各種行為缺陷。一些自閉症兒童在使用抗菌藥物時有效對抗腸道梭菌，自閉症典型行為會顯著減少。(但只屬短暫效果)
神經遞質的釋放協助神經細胞傳遞訊息
Image from qbi.uq.edu.au
Autism is a severe developmental disability believed to have multiple reasons. This paper outlines the possibility of a chronic tetanus infection of the gastrointestinal tract (GIT) as the underlying cause for symptoms of autism observed in some individuals.
A significant percentage of individuals with autism have a history of extensive antibiotic use. Oral antibiotics significantly disrupt protective intestinal microbiota, creating a favorable environment for colonization by opportunistic pathogens. Clostridium tetani is a general anaerobic bacillus that produces a potent neurotoxin... The vagus nerve is capable of transporting tetanus neurotoxin (TeNT) and provides a route of ascent from the intestinal tract to the central nervous system (CNS)…Once in the brain, TeNT disrupts the release of neurotransmitters...This inhibition of neurotransmitter release would explain a wide variety of behavioral deficits apparent in autism...Some children with autism have also shown a significant reduction in stereotyped behaviors when treated with antimicrobials effective against intestinal clostridia…
Bolte, E. R. (1998). Autism and Clostridium tetani[Abstract]. Medical Hypotheses, 51(2),133-144. doi.org/10.1016/S0306-9877(98)90107-4
Autism was once exceedingly rare...By the time the first real surveys were done in the 1960s, around 1 in 2500 children were affected...At the time of last count, in 2010, the number stood at 1 in every 68 children...
Mental health and antibiotics
Diarrhea is often a side effect of antibiotics...
Clostridium difficile infections cause severe intractable (難治療的) diarrhea in some people after they have been given antibiotic treatment...
For sufferers of long-term conditions such as irritable bowel syndrome, emotion plays a fearsome role in their symptoms...
Sudo and Chida designed a simple experiment, using mice, that looked at whether the gut microbiota affected the brain's response to stress... in the germ-free (in the gut) mice the (stress) hormone concentrations were twice as high...
...Many microbes were (soon) linked to mental illness, but it is the Toxoplasma parasite that has proved to be the most compelling suspect for many conditions...
...Introducing live bacteria (to the gut) increases levels of tryptophan in the blood. This little molecule is of paramount (首要的) importance of happiness, as it is converted directly into serotonin...the increase in tryptophan that the added bacteria bring about is not because they make it, but rather because they prevent the immune system from destroying the body's supplies of it...
Collen, A. (2015) 10% Human: How Your Body's Microbes Hold the Key to Health and Happiness. London: William Collins.
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