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利用先进脑部扫描技术发现阿尔海默症先兆

时间:2010-09-14 14:38来源: 作者: 阅读:

一项最新研究显示,在症状来临前,即可用先进的脑部扫描技术提早发现阿尔海默症。

加州大学洛杉矶分校本周末宣布,其研究人员对169名轻度认知障碍患者进行了为期三年的跟踪调查。此病对记忆功能的不良影响要大于年龄的影响,但不会像阿尔海默症那样造成性格和认知功能的改变。

三年后,这些病人当中的一些患上了阿尔海默症。而这些病人在脑部海马的两个特定区域出现萎缩的几率比其他未患此病者高出10%30%。(海马是大脑中对长期记忆至关重要的部分。)

在另一项调查中,研究者先对十名认知功能正常的老年人进行了脑部扫描,后将他们的检查结果与七名由轻度认知障碍发展为阿尔海默症的老年患者患病前的扫描结果进行比对,再次发现患病者在脑部海马的相同区域出现了同型的萎缩现象。

研究人员称,那些日后患上轻度认知障碍的人在认知功能正常时就已出现了海马过度萎缩。患病后萎缩进一步加剧,当其最终蔓延至整个海马时导致阿尔海默症的出现。

该大学神经学助理研究员雷奥娜·阿波斯特洛娃说:“我们认为这一发现十分重要,因为这是从活人身上得出的结论。现在我们掌握了一项敏感技术,能够显示“不可见”的层面,即一种疾病在其症状出现之前的发展变化情况。”

她还说:“想从脑部扫描的检查结果中判明海马萎缩的程度并不容易。另外,想观察萎缩的进展情况需要用到十分敏感的技术。”

她表示:“我们不能观察到病理变化,但能清楚地看到与轻度认知障碍和阿尔海默症相关联的神经退化萎缩现象以及这一现象在海马中蔓延的迹象。这正是生物标记物的主要功能,它可作为观察疾病发展的间接指标。”

Sophisticated brain scans can help detect theprecursors to Alheimer's disease before any symptoms begin, accordingto a new study.

The University of California in Los Angeles(UCLA) announced at the weekend that its researchers tracked 169 peopleover three years who had been diagnosed with mild cognitive impairmentor MCI, a condition that causes memory problems greater than thoseexpected for an individual's age -- but not the personality orcognitive changes that define Alzheimer's.

They discoveredthat after three years, those who went on to be diagnosed withAlzheimer's disease showed a 10 to 30 percent greater atrophy in twospecific locations within the brain's hippocampus, a part of the brainknown to be critical for long- term memory.

In anotherstudy, researchers looked at 10 cognitively normal elderly people andcompared their brain scans with those of seven other elderly people whowere later diagnosed with MCI and then Alzheimer's disease. Again, theyfound that the group that went to be diagnosed with Alzheimer's showedthe same pattern of atrophy in the same regions of the hippocampus.

Researcherssaid that excess atrophy is present in cognitively normal individualswho are predestined to develop MCI. Further, that atrophy ultimatelycascades across the entire hippocampus of the brain, leading toAlzheimer's disease.

"We feel this is an important findingbecause it is living humans," said UCLA assistant clinical professor ofneurology Liana Apostolova. "Now we have a sensitive technique thatshows the ' invisible' -- that is the progression of a disease beforethe symptoms appear."

Apostolova said the degree of atrophyis not easily visible in the brain scans and that very sensitivetechniques are required to show its progression.

"We can'tsee the pathologic changes, but we clearly see the neurodegenerativeatrophy associated with MCI and AD (Alzheimer's disease), and how itspreads through the hippocampus," she said. " This is exactly what abiomarker, being an indirect measure of disease progression, issupposed to do."

(责任编辑:glia)
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