自闭研究的突破性进展

杰赋

加州大学洛杉矶分校的最新研究发现自闭/多动症与myelin(神经周围包围的绝缘层) 生成受损有关。 此研究是基于回顾以往大脑扫瞄和尸检脑组织的研究结果。(http://www.upi.com/ConsumerHealthDaily/view.php?StoryID=20060316-091132-9736r)

Dr Bartzokis的研究还发现女童的myelin生成要好于男童，这可解释为何自闭症的男女性比会大于4:1.
如自闭真与myelin (神经周围包围的绝缘层) 有关，则许多自闭症状都可解释了。
如疼觉不敏感，撞头等可能是因为疼觉信号中途流失太多，以至不感到疼痛。(正常状态下，也有大于90%的神经信号会流失。)
如某些感觉太敏感，可能是因为神经感觉信号的阈值太小，而神经感觉信号的阈值是与神经感觉信号的大小及神经联系有关。(感统训练的一结果是调整感觉信号的阈值)
如斜眼看人，可能是因为双眼神经输入信号流失不平衡。
如注意力不集中， 可能是因为大脑内部的神经控制信号流失有关。
如前不久报道的脑内灰物质少， 是因为大脑内外的联系和刺激少， 当然会影响大脑皮质的发育生成。
鱼油对myelin 的生成有益。 Dr Bartzokis认为， 欧米各-3是生成酶(membrane)的必须物质，而myelin 基本上是纯酶。但究竟是如何起作用的还是一个谜。


我个人以为，在此研究的基础上一两年内自闭成因会有决定性的结论。

杰赋

Ped Med: The skinny on ADHD contributors
By LIDIA WASOWICZ (UPI Senior Science Writer )
SAN FRANCISCO, March 17 (UPI) -- Nutritionists are convinced that, just like everyone else, children with attention-deficit/hyperactivity disorder are what they eat.
Specifically, the specialists have their eye on so-called omega-3 fatty acids as playing some role in the condition that, in general, is marked by trouble keeping still, difficulty in maintaining attention, propensity toward acting impulsively or some combination of the three.
Omega-3 fatty acids are plentiful in cold-water fish, such as salmon, herring, tuna, clams, crab, cod, flounder, sole, halibut, catfish, trout and shrimp. They also abound in nuts; soybeans; walnut, olive and flaxseed oil; seeds; whole grains and dark leafy greens.
The fatty acids comprise a hefty component of the brain, which weighs in at about 60-percent fat.
The compounds, which studies indicate are essential for forming and maintaining the dopamine system, have been found in short supply in some, though not all, children diagnosed with ADHD.
Many researchers see ADHD as a hereditary imbalance of brain chemicals, such as dopamine -- which regulates movement, emotion, motivation and sensations of pleasure.
That view is strongly contested by critics who point to a dearth of physical evidence for such a notion.
Whatever their connection to the "feel-good" chemical in the brain, the omega-3 fatty acids appear to have an impact on a child's behavior, portending problems in youngsters who don't have enough of the compounds.
As one example, a recent Duke University study of 96 boys ages 6 to 12 indicated those with low blood levels of omega-3 fatty acids face increased risk of ADHD-like behavior, learning and health challenges.
There is also some evidence the compounds may play a benevolent role in the production of myelin, a protective insulation that coats the brain's internal wiring,
A novel model of human brain development and degeneration proposed by researchers at the University of California, Los Angeles implicates disruption of myelin production in such childhood developmental disorders as autism and ADHD.
From a review of scanned and autopsied brain tissue, the investigators unraveled the role of myelin in these conditions.
Laden with more cholesterol than any other brain component, the sheet of fat surrounds the spindly nerve-cell extensions called axons, permitting them to carry messages to their neighbors in the safety and security of their armor.
The thicker and heavier the cells' coat, the faster and more effective their communication, said team leader Dr. George Bartzokis, professor of neurology at the David Geffen School of Medicine and director of the UCLA Memory Disorders and Alzheimer's Disease Clinic and the Clinical Core of the UCLA Alzheimer's Disease Research Center.
The pioneering neuroscientist discovered that myelin production continues unabated throughout the first four decades of life before peaking and plummeting at age 45. His latest research portrays the protective shield as the neural system's Achilles' heel, vulnerable to a host of environmental assaults.
"Myelination, a process uniquely elaborated in humans, arguably is the most important and most vulnerable process of brain development as we mature and age," Bartzokis said.
Without adequate insulation, cells won't connect properly, he has found in a series of experiments that showed a breakdown in the sheath can expose the naked wiring beneath and open the gates to an array of neurological and behavioral problems.
Bartzokis's theory holds that humans "myelinate" different circuits at various points in life, which could explain the sizeable differences between brain diseases of the young and old.
An early disruption of the process, for instance, may throw for a loop the development of the basic circuits that govern language and social communication, two key impairments in autism.
A glitch during the early school years could hamper the ability to process information efficiently and effectively, leading to deficits in attention that characterize ADHD. Later in life, the result of a malfunction could be Alzheimer's disease.
To Bartzokis, the human brain is akin to high-speed Internet.
"The speed, quality and bandwidth of the connections determine the brain's ability to process information, and all these depend in large part on the insulation that coats the brain's connecting wires," he said.
The findings may explain why developmental disorders leave no calling card in the brain. "There's no dead anything on autopsy," Bartzokis said. "Those brain connections just never developed normally."
Bartzokis's studies also show female brains make better myelin, which could explain why boys are at much greater risk for autism, ADHD and other problems.
"On the positive side, there are some interesting things to consider," Bartzokis said. "For example, essential fatty acids are fats that are necessary for membrane production, and myelin is essentially pure membrane."
"They are called 'essential' because the human body cannot produce them, and, therefore, they are like 'vitamins' -- they need come from a good diet," he added. "Thus, nutrition is very important because the brain is very busy trying to build the myelin sheaths."
Still, researchers don't have the skinny on the exact relationship between the fats and ADHD.
Although alternative medicine practitioners report some success in ameliorating symptoms with the use of fatty acid, mineral, vitamin B and other supplements, none of these has been embraced as standard therapy.
Conventional and complementary practices also part ways on the role, and remedial potential, of food additives, sugar or allergens. All of these remain controversial, having failed to withstand rigorous scientific scrutiny, according to a compilation of ADHD data by Dr. Peter Jensen, director of the Center for the Advancement of Children's Mental Health at Columbia University.
Next: Seeking environmental clues to ADHD.
(Editors' Note: This series on ADHD is based on a review of hundreds of reports and a survey of more than 200 specialists.)
--

5i52

谢谢你的信息.

记不得是<<生物疗法>>还是<<大脑饥饿的孩子>>里讲到神经周围包围的绝缘层受损的话题,而且还给出原因.

大脑的问题，有的说里面化学物质不平衡，有的说物理上有问题（诸如大了，小了的之类的），也有的说大脑结构和脑神经，脑细胞没问题，只是脑神经之间的联系少了。至于为什么少，就有神经周围包围的绝缘层受损的这个说法，很好理解，就像电子电路短路或者是断路了。研究还发现女童的myelin生成要好于男童，这真是个重要的信息，不过能给出原因会更好。

楼主后面的分析我认为很有道理。

不过一两年内自闭成因会有决定性的结论的说法我认为太过乐观.我也曾乐观过.
自闭症超级复杂, 一二十年后都不一定有结论.

秋爸爸

感谢楼主的信息。但这信息尚不能称为“突破性进展”，只能算对于近年来髓脂形成与神经障碍及涉及的某些精神疾病的相关性研究的综述性科普报道。相比之下，最近报道的科学家已建立出小鼠的自闭症模型，在研究进展上更具有“突破性”。有了动物模型，许多研究可以在动物进行试验和验证。但即便如此，自闭症的科学研究的路途还是太遥远啦，且不说这个动物模型是否有诸多适用局限。我个人一点儿都不乐观，甚至悲观。想想看，艾滋病、肿瘤这类疾病的研究，广泛性、深入性以及巨大的资源投入，都远远超过了自闭症研究，而且其发病机制已经了解得比较清楚，各种动物模型甚至临床药物也都有很多的应用，但在未来的几十年之内，它们也还会属于难于最终解决的医学难题。自闭症和上文主要涉及的注意力缺陷/多动症，目前都认为是脑病，或者神经系统的发育障碍疾病，都认为具有明显的遗传因素，对它们的研究领域还广泛涉及到免疫系统、代谢系统等，（生命就是牵一发动全身的“系统”），每一方面都有着各自的研究进展，可是如果因此单纯地从某一些方面的最新科研报告中，获取可以直接应用的治疗线索，也许会很片面、很可能最终令人失望。这些看法也是我个人目前对排毒、禁食甚至感统等做法表示怀疑的原因之一。

binfeng2000

秋爸爸讲的"最近报道的科学家已建立出小鼠的自闭症模型",可能是指下面的报道.这个发现有其特殊的意义,是因为老鼠是天生的"社交性"动物,文章举例说,正常的老鼠,如果你在里面放一包棉花,几个老鼠马上会分享并且合力建成一个老鼠窝,但这些被除去了P-十基因的实验室老鼠,根本就视而不见.
我也赞同秋爸爸的观点,一些基础性的探索还远远没有到了能搞清楚自闭症因果关系的时候,尤其对于那些生物治疗的观点来讲,那些已知的试验报告,临床试验还远远没有取的明确的广泛的结论,更不要说从动物试验到人体试验了.

有关上文中的那个试验,摘引如下:

RESEARCH

Autism, A Little Understood Disorder May Have Genetic Roots         

      By Carol Pearson for Voice of America
http://www.voanews.com/english/2006-05-29-voa16.cfm

      Researchers at the University of Texas Southwestern have been able to
genetically change mice so their behavior is similar to some people with
autism.  The researchers hope their discovery will eventually lead to
treatment for people with autism spectrum disorder.
      Mice are genetically similar to people which is why geneticists such
as Eric Lander study them. "We might think of ourselves as different than a
mouse because we're so much bigger and we think we're so much smarter, but
look inside, the organs are all the same." Including the brain.  Researchers
led by Professor Luis Parada at the University of Texas Southwestern have
found that by deleting a gene called P-ten in certain parts of the mouse
brain, they created mice that act like people with autism spectrum disorder,
a range of disorders in which people have trouble with communication and
social interaction:  they may not even look at people they are with. They
may also exhibit other strange behaviors: walking on their toes, and
flapping their arms.
      Professor Luis Parada directs the university's Center of Developmental
Biology.  He says by genetically altering the mice, he got some of the same
behavior as people who have autism. "The abnormal behaviors are based on the
fact that mice are extremely social animals."
      Mice are generally interested in other mice, but not mice whose P-ten
gene has been deleted. Professor Parada says the genetically altered mice
have other social deficits. "If one gives mice in a box cotton material,
they will quickly shred it and transform it into a three-dimensional nest
and go and burrow under it.  When the mutant mice are given this nesting
material they completely ignore it."
      The genetically altered females also ignore their offspring.
      "The P-ten mice they wouldn't let you pick them up. They're just
really skittish just like autistic children are.  They don't like to be
picked up."
      Autism affects about one in every 250 people, yet little is known
about this disorder or how to treat it which is why the genetic research
with mice is so important.
      "It gives us at least a first clue as to where the mutations in the
brain could result in deficits in social interaction." Professor Parada says
the next step is to treat the genetically altered mice with drugs to see if
it is possible to reverse the condition. The research might lead someday to
a cure for autism spectrum disorder and similar genetic abnormalities in
people.