wkoiu 2010-2-11 12:35
MEG可以提供創傷後壓力異常的客觀診斷
作者：Janis C. Kelly
出處：WebMD醫學新聞
January 27, 2010 — 腦磁圖儀(MEG)可以客觀地診斷創傷後壓力異常(PTSD)，傳統上是使用腦部掃描，包括電腦斷層以及磁振造影，但是都失敗了。
明尼蘇達州明尼拿波里退伍軍人醫學中心腦部科學中心主任Apostolos P. Georgopoulos醫師等研究者表示，MEG可以成功地區別PTSD病患和健康對照組。
Georgopoulos醫師向Medscape Psychiatry表示，這篇研究的結果可能會改變對於PTSD的基本瞭解，首先，它確定PTSD是一種生物基質的腦部疾病，接著，藉由研究確認的話，它在PTSD的各方面將帶來新的瞭解、指引與預測。
不過，獨立的影像與PTSD專家們採取更謹慎的方法看待這個研究發現，認為還不足以宣示以MEG作為PTSD的確定診斷檢測。
這項研究線上發表於1月20日的神經工程期刊(Journal of Neural Engineering)。
【確實的差異】
透過回顧美國退伍軍人的臨床紀錄確認可能的對象，確認那些使用結構式臨床診斷訪視、目前有PTSD診斷者，總共有74名PTSD退伍軍人，曾在第二次世界大戰、阿富汗或伊拉克服役，有250名招募自一般大眾的健康對照組。
當這些研究對象進行一項「固定任務」時進行影像檢查，此項固定任務是，將他們的眼睛固定看著前方645公分處的一點、歷時60秒。這個同步神經互動(SNI)檢測結果，評估了各類型神經人口的功能性互動，之後比較PTSD組和對照組。
研究者報告指出，他們可以從健康對照組中區別PTSD病患，準確率超過90%，根據SNI與他們的症狀嚴重度，發現PTSD病患之間確實有明顯關聯。
研究作者們寫道，總而言之，這些發現證明PTSD和對照組之間的腦部功能確實有所差異，可以用來區別診斷，也擁有評估、監測疾病病程和治療效果的潛力。
若如此，此技術將是PTSD生物標記研究上的重大突破，但是其他的PTSD影像專家則對此抱持謹慎態度。
【需謹慎】
德國Konstanz大學的Iris-Tatjana Kolassa醫師對這些結果發表評論時表示，這些發現新添了文獻證據，但是需要謹慎的後續研究，以顯示其運用於診斷此狀況的能力。Kolassa醫師使用MEG為基礎的影像，對災難和戰爭後有PTSD的存活者其異常腦部功能進行區域位置分析。
Kolassa醫師向Medscape Psychiatry表示，我們知道有許多研究，包括我們自己實驗室的研究認為，測量神經震盪和同步是腦部結構的敏感指標，且和心智異常相關。
Kolassa醫師以及另一位受邀發表評論的紐約市Mount Sinai醫學院的Alexander Neumeister醫師，都表示對於實驗組和對照組組成的關注。
Kolassa醫師表示，對照組招募自一般大眾，而不是和病患相同的族群，因此這兩組之間有相當多的差異因素，包括一般教育、社會經濟狀態、病患狀態等，因此，觀察到的差異可能不是因為PTSD，而是因為非特定變項或其他常見的共病症狀，例如憂鬱症、身心症、以及藥物濫用或治療史。
健康人和病患之間有許多變項有差異，得使用事後分析方法來區分這些變項的差異。
Neumeister醫師最近報告了有共病症的PTSD病患與單純PTSD病患的腦功能差異，認為該研究提供了有趣的初步資料，但是也僅止於此。他指出，那是一個小型研究，在缺乏這些研究對象服用的藥物資訊下很難進行詮釋。
他表示，其中許多是年長病患，可能會有高血壓、心血管問題、糖尿病、或其他需要治療的狀況。我們知道，即使只是有沒有喝咖啡都會影響MEG，將這些醫療狀況納入將是很重要的。
他指出，PTSD也會和憂鬱及其他問題同時發生，而研究中未提及這些病患是否有接受治療，例如選擇性血清素再吸收抑制劑，會整個搞亂MEG的判讀。
Neumeister醫師結論表示，這個報告有一些限制，它很有趣，但是我們不可以就這樣結論說這是一個診斷PTSD的方法，希望由其他沒有相關財經利益的研究者重現這個研究。
Georgopoulos醫師對於該研究依舊抱持樂觀，認為PTSD組和對照組之間的腦功能有明顯差異，可以用來區別診斷且有潛力評估和監測疾病病程與治療效果，他的團隊曾經在其他腦部疾病如阿茲海默氏症與多發性硬化症報告過類似的MEG「記號」，他們正規劃對PTSD進行更大型的研究。
美國退伍軍人事務部以及美國美國退伍軍人協會腦部科學中心支持本研究。Georgopoulos醫師與本研究所用的技術有財務利益關係。
Neumeister醫師宣告與Eli Lily、Pfizer以及Ortho-McNeil-Janssen Pharmaceuticals有財務關係。Kolassa醫師宣告沒有相關財務關係。
J Neural Eng. 線上發表於2010年1月20日。
MEG May Provide Objective Diagnosis of Posttraumatic Stress Disorder
By Janis C. Kelly
Medscape Medical News
January 27, 2010 — Magnetoencephalography (MEG) may have the potential to objectively diagnose posttraumatic stress disorder (PTSD) — something conventional brains scans, including computed tomography and magnetic resonance imaging, have failed to do.
New research, led by Apostolos P. Georgopoulos, director of the Brain Sciences Center, Veterans Affairs Medical Center, Minneapolis, Minnesota, suggests that MEG can successfully differentiate PTSD patients from healthy control subjects.
Dr. Georgopoulos told Medscape Psychiatry that the results of this study are likely to change basic understanding of PTSD. "First, it establishes PTSD as a brain disease with a biological substrate. Then, with work on [validation], it can bring new understanding, guidance, and prediction to several PTSD dimensions," he said.
However, independent imaging and PTSD experts are taking a more cautious approach to the study findings, saying it is premature to declare MEG as a definitive diagnostic test for PTSD.
The study was published online January 20 in the Journal of Neural Engineering.
Robust Differences
Potential subjects were identified through a clinical records review of US veterans to identify those with a likely current PTSD diagnosis using a structured clinical diagnostic interview. A total of 74 veterans with PTSD who had served in World War II, Vietnam, Afghanistan, or Iraq and a control group of 250 healthy controls recruited from the general public participated in the study.
Imaging was performed while subjects engaged in a fixation task: fixing their eyes on a spot about 645 cm in front of them for 60 seconds. The results of this synchronous neural interactions (SNI) test, which assesses the functional interactions among neural populations, were then compared in the PTSD and control groups.
The researchers report that they were able to differentiate PTSD patients from healthy control subjects with more than 90% accuracy and that there was a "significant association found between the certainty of PTSD patient classification based on the SNI and their symptom severity."
"Altogether, these findings document robust differences in brain function between the PTSD and control groups that can be used for differential diagnosis and which posses the potential for assessing and monitoring disease progress and effects of therapy," the study authors write.
If so, this technique would represent a breakthrough in the search for a biomarker for PTSD, but other experts in PTSD imaging are more cautious.
Caution Warranted
Commenting on the findings, Iris-Tatjana Kolassa, MD, University of Konstanz, Germany, who has also used MEG-based source imaging to map abnormal brain activity in survivors of torture and war with PTSD, said the findings add to the literature but cautions that further research needs to be done to demonstrate its utility in diagnosing the condition.
"We know from a number of studies, including those from our own lab, that measures of neural oscillations and synchrony are sensitive indicators of the brain's architecture, also in relation to mental disorders," Dr. Kolassa told Medscape Psychiatry.
Both Dr. Kolassa and Alexander Neumeister, MD, Mount Sinai School of Medicine, New York City, who has also commented on the study, were concerned by the composition of the subject and control groups.
"The control group was recruited from the general public, not from the same population as the patients. Quite a number of factors therefore differentiate the 2 groups. These might range from general education, socioeconomic status, to patient status, etc. Thus, the observed differences may not arise from PTSD but from unspecific variables or from frequently comorbid symptoms, such as depressive symptoms, somatization, and especially drug abuse or history of medication.
"Many variables differentiate between healthy and sick people, and it may not be too difficult to differentiate such variations with a post hoc measure," said Dr. Kolassa.
Dr. Neumeister, who recently reported on brain function differences in patients with PTSD and comorbidities vs PTSD alone, said the study provides "interesting preliminary data but not more than that."
He noted that it was a small study and that interpretation is complicated by the lack of information on medications subjects may have been taking.
"Many of these were older patients, who might be expected to have hypertension, cardiovascular problems, diabetes, or other conditions requiring treatment. Since we know that even just drinking coffee vs not drinking coffee can affect MEG, it would be important to account for medications," he said.
"PTSD also goes along with depression and other problems, and there is no mention of whether these patients were receiving treatments, such as selective serotonin reuptake inhibitors, which completely mess up MEG readings," he added.
"This paper has some limitations. It is interesting, but people should not conclude that this is a way to diagnosis PTSD," Dr. Neumeister concluded. He also would like to see this study replicated by researchers who have no financial interest in the outcome.
Dr. Georgopoulos remains optimistic that the study has documented "robust differences in brain function between the PTSD and control groups that can be used for differential diagnosis and that possess the potential for assessing and monitoring disease progression and effects of therapy." His group has previously reported similar MEG "signatures" for other brain diseases, such as Alzheimer's disease and multiple sclerosis. They are moving forward with larger studies in PTSD.
The study was supported by the US Department of Veterans Affairs and the American Legion Brain Sciences Chair. Dr. Georgopoulos has a financial interest in the technology used in this study. Dr. Neumeister has disclosed financial relationships with Eli Lily, Pfizer, and Ortho-McNeil-Janssen Pharmaceuticals. Dr. Kolassa has disclosed no relevant financial relationships.
J Neural Eng. Published online January 20, 2010.