Sustained stress erodes memory, and the immune system plays a key
role in the cognitive impairment, according to a new study from
researchers at The Ohio State University.
The work in mice could one day lead to treatment for repeated,
long-term mental assault such as that sustained by bullying victims,
soldiers and those who report to beastly bosses, the researchers say.
"This is chronic stress. It's not just the stress of giving a talk
or meeting someone new," said lead researcher Jonathan Godbout,
associate professor of neuroscience at Ohio State.
This is the first study of its kind to establish the relationship
between short-term memory and prolonged stress. In the case of the mice,
that meant repeat visits from a larger, nasty intruder mouse.
Mice that were repeatedly exposed to the aggressive intruder had a
hard time recalling where the escape hole was in a maze they'd mastered
prior to the stressful period.
"The stressed mice didn't recall it. The mice that weren't stressed, they really remembered it," Godbout said.
They also had measurable changes in their brains, including evidence
of inflammation brought on by the immune system's response to the
outside pressure. This was associated with the presence of immune cells,
called macrophages, in the brain of the stressed mice.
The research team was able to pin the short-term memory loss on the inflammation, and on the immune system.
Their work, which appears in The Journal of Neuroscience, builds on previous research substantiating the connections between chronic stress and lasting anxiety.
The impact on memory and confirmation that the brain inflammation is
caused by the immune system are important new discoveries, Godbout
said.
"It's possible we could identify targets that we can treat pharmacologically or behaviorally," he said.
It could be that there are ways to interrupt the inflammation, said
John Sheridan, who worked on the study and is associate director of Ohio
State's Institute for Behavioral Medicine Research.
The mice used in the study are exposed to repeated social defeat -
basically dominance by an alpha mouse - that aims to mimic chronic
psychosocial stress experienced by humans.
Researchers at Ohio State seek to uncover the secrets behind stress
and cognitive and mood problems with a long-range goal of finding ways
to help those who are anxious, depressed and suffer from lasting
problems, including post-traumatic stress disorder.
This new research focused on the hippocampus, a hub of memory and emotional response.
The researchers found that the stressed mice had trouble with
spatial memory that resolved within 28 days. They found that the mice
displayed social avoidance, which measures depressive-like behavior,
that continued after four weeks of monitoring.
And they were able to measure deficits in the development of new neurons 10 days and 28 days after the prolonged stress ended.
When they gave the mice a chemical that inhibited inflammation,
neither the brain-cell problem nor the depressive symptoms went away.
But the memory loss and inflammatory macrophages did disappear.
And that led them to conclude that the post-stress memory trouble is
directly linked to inflammation - and the immune system - rather than
to other damage to the brain. That type of information can pave the way
for immune-based treatments, Godbout said.
"Stress releases immune cells from the bone marrow and those cells
can traffic to brain areas associated with neuronal activation in
response to stress," Sheridan said. "They're being called to the brain,
to the center of memory."
###
The researchers' work was supported by the National Institutes of
Health, the National Institute of Aging and the National Institute of
Dental and Craniofacial Research.
Other Ohio State researchers who worked on the study were Daniel McKim, Anzela Niraula, Andrew Tarr and Eric Wohleb.
CONTACTS: Jonathan Godbout, 614-293-3456; Jonathan.Godbout@osumc.edu John Sheridan, 614-293-3571; John.Sheridan@osumc.edu
Written by: Misti Crane, 614-292-5220; Crane.11@osu.edu
Some 20 patients had bone marrow transplants using their own stem cells，Some patients who were paralysed have been able to walk again. 已經有20人 使用他們自己的造血幹細胞透過骨髓移植的方式進行此手術，其中有一些已經癱瘓的可以再度行走(不是全部)。詳細數字需要再進一步追!追!追!
Their faulty immune systems were destroyed using chemotherapy 透過化療的方式摧毀原本異常的免疫系統
Then, it was rebuilt with stem cells harvested from their own blood 然後再用自身原有的造血幹細胞中移植入體內去重新啟動
MS Society said treatment was 'life-changing' but warned it is aggressive and may not be effective for all MS patients。國際MS社群組織表示：這個手術雖然能夠讓生活改變，但是並不一定適用於每一位病友。
Steven Storey治療前他連腳趾頭都無法動彈, 而且失去了大部分的感覺，但治療後幾個月後他不用協助就可以自行站立，現在他還需要輪椅，但是他已經可以游泳並且騎腳踏車。圖片來源：BBC
Sam Ramsey, 因為得到MS而癱瘓，但治療後她可以靠著拐杖走路而且考到駕駛執照。
Dr
Emma Gray, head of clinical trials at UK's MS Society, said: 'Ongoing
research suggests stem cell treatments such as HSCT could offer hope,
and it's clear that, in the cases highlighted by Panorama, they've had a
life-changing impact.
'However,
trials have found that, while HSCT may be able to stabilise or improve
disability in some people with MS, it may not be effective for all types
of the condition.
此實驗性治療手術也發現，某些病人當中甚至肢障程度變得嚴重 。
'We
want people to be aware that HSCT is an aggressive treatment that comes
with significant risks. It needs to be carried out at an accredited
centre or as part of a clinical trial.
一篇來自 Debra Kain – University of Virginia Health System 發表的論文：中樞神經系統的淋巴管的結構和功能特徵 Structural and functional features of central nervous system lymphatic vessels
The unexpected presence of the lymphatic vessels raises a tremendous number of questions that now need answers, both about the workings of the brain and the diseases that plague it. For example, take Alzheimer’s disease. “In Alzheimer’s, there are accumulations of big protein chunks in the brain,” Kipnis said. “We think they may be accumulating in the brain because they’re not being efficiently removed by these vessels.” He noted that the vessels look different with age, so the role they play in aging is another avenue to explore. And there’s an enormous array of other neurological diseases, from autism to multiple sclerosis, that must be reconsidered in light of the presence of something science insisted did not exist.
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