گونه ای اسكن مغزی می تواند تغییرهای زیست-شیمایی در مغز افراد سالمی كه ممكن است در معرض خطر ابتلا به آلزایمر باشند را شناسایی كند. این دستاورد پژوهش تازه ای است كه گزارش آن در شماره 24 آگست "نورولوژی،" مجله پزشكی اكادمی عصب شناسی آمریكا، انتشاریافته است.
در این مطالعه 311 نفر در دهه های 70 و 80 سالگی عمر خود، بی هیچ نوع مشكل شناختی و از نمونه اجتماعی كلینیك مطالعه سالمندی مایو، با استفاده از یك روش پیشرفته تصویربرداری مغزی، كه طیف سنج پروتون ام.آر. نامیده می شود، مورد اسكن مغزی قرار گرفتند تا بررسی شود آیا موردهای غیر عادی در چند متابولیت كه ممكن است نشانگرهای زیستی برای بیماری آلزایمر باشند در آنها وجود دارد یا نه. آنها همچنین مورد پت اسكن قرار گرفتند تا میزان انباشت آمیلوید-بتا یا جرم (پلاك) در مغز، یكی از اولین نشانه های تغییرها در مغز در نتیجه آلزایمر، اندازه گیری شود. شركت كنندگان همچنین مورد آزمون های حافظه، زبان و دیگر مهارت ها قرار گرفتند.
دكتر جاناتان ام. شوت، از مركز پژوهش زوال عقل در دانشگاه كالج لندن در انگلستان و یك عضو اكادمی آمریكایی عصب شناسی، در سرمقاله ای به همراه گزارش مطالعه نوشت: "مستندهای فزاینده ای وجود دارد كه بیماری آلزایمر با تغییرهایی در مغز پیوند دارد كه سالها پیش از آن كه عارضه های بیماری بروز كند شروع می شود. اگر ما می توانستیم كسانی را شناسایی كنیم كه در آنها فرایند بیماری آغاز شده اما عارضه های آن هنوز ظاهر نشده، ما می توانستیم دریچه فرصتی به سوی مداواهای بالقوه بگشاییم – تا وقتی كه آنها آماده می شود موجب به تاخیر انداختن و یا مانع از دست دادن حافظه و توان های شناختی گردد."
این مطالعه نشان داد كه 33 درصد از شركت كنندگان میزان های قابل توجه بالایی از انباشت آمیلوید-بتا در مغز خود داشتند. دارندگان انباشت آمیلوید-بتا همچنین تمایل داشتند تا میزان های بالایی از متابولیت های مغزی مایو اینوسیتول/كریتاین و كولین/كریتاین داشته باشند. كسانی كه میزان های بالایی از كولین/كریتاین داشته باشند احتمال بیشتری دارد كه امتیازهای كمتری در آزمون های شناختی به دست آورند – بی توجه به میزان انباشت آمیلوید-بتا در مغز آنها. [ادامه در زیر ...]
Study Identifies Chemical Changes in Brains of People at Risk for Alzheimer's Disease
MedicalXpress | August 24, 2011
A brain imaging scan identifies biochemical changes in the brains of normal people who might be at risk for Alzheimer's disease, according to research published in the August 24, 2011, online issue of Neurology, the medical journal of the American Academy of Neurology.
The study of 311 people in their 70s and 80s with no cognitive problems, from the population-based Mayo Clinic Study of Aging, used an advanced brain imaging technique called proton MR spectroscopy to see if they had abnormalities in several brain metabolites that may be biomarkers for Alzheimer's disease. They also had PET scans to assess the level of amyloid-beta deposits, or plaques, in the brain that are one of the first signs of changes in the brain due to Alzheimer's disease. The participants were also given tests of memory, language and other skills.
"There is increasing evidence that Alzheimer disease is associated with changes in the brain that start many years before symptoms develop," said Jonathan M. Schott, MD, of the Dementia Research Centre, University College London in England and a member of the American Academy of Neurology, who wrote an editorial accompanying the study. "If we could identify people in whom the disease process has started but symptoms have not yet developed, we would have a potential window of opportunity for new treatments—as and when they become available—to prevent or delay the start of memory loss and cognitive decline."
The study found that 33 percent of the participants had significantly high levels of amyloid-beta deposits in their brains. Those with high levels of amyloid-beta deposits also tended to have high levels of the brain metabolites myoinositol/creatine and choline/creatine. People with high levels of choline/creatine were more likely to have lower scores on several of the cognitive tests, regardless of the amount of amyloid-beta deposits in their brains.
"This relationship between amyloid-beta deposits and these metabolic changes in the brain are evidence that some of these people may be in the earliest stages of the disease," said study author Kejal Kantarci, MD, MSc, of the Mayo Clinic in Rochester, Minn., and a member of the American Academy of Neurology. "More research is needed that follows people over a period of years to determine which of these individuals will actually develop the disease and what the relationship is between the amyloid deposits and the metabolites." At the present time, MR spectroscopy cannot be used for diagnosis.
Provided by American Academy of Neurology (news : web)
Brain Scan Detects Alzheimer's Disease Risk in Healthy Individuals
Main Category: Alzheimer's / Dementia
Also Included In: Radiology / Nuclear Medicine; MRI / PET / Ultrasound; Neurology / Neuroscience
MNT | Article Date: 24 Aug 2011 | Written by Christian Nordqvist
Biochemical changes in the brains of healthy individuals can be identified by an imaging technique - proton MR spectroscopy - indicating whether they may be at risk for Alzheimer's disease, researchers from the Mayo Clinic reported in the journal Neurology.
Kejal Kantarci, MD, MSc, and team carried out a study involving 311 participants aged over 70 years from the May Clinic Study of Aging. None of them had cognitive problems. Proton MR spectroscopy, an advanced brain imaging technique, was used to determine whether any of them had abnormalities in various brain metabolites that might be Alzheimer's disease biomarkers.
PET scans were used to assess amyloid-beta deposits (plaques) in the brain. Plaques are one of the initial signs of Alzheimer's disease onset. The volunteers also underwent various tests which assessed their language, memory and other skills.
Jonathan M. Schott, MD, of the Dementia Research Centre, University College London, England, said:
"There is increasing evidence that Alzheimer disease is associated with changes in the brain that start many years before symptoms develop.
If we could identify people in whom the disease process has started but symptoms have not yet developed, we would have a potential window of opportunity for new treatments - as and when they become available - to prevent or delay the start of memory loss and cognitive decline."
33% of the volunteers had considerably high levels of amyloid-beta deposits. Those people also had high levels of brain metabolites choline/creatine and myoinositol/creatine. Those with high choline/creatine levels tended to score poorly on various cognitive tests, regardless of brain amyloid-beta deposit levels.
Dr. Kantarci said: "This relationship between amyloid-beta deposits and these metabolic changes in the brain are evidence that some of these people may be in the earliest stages of the disease.
More research is needed that follows people over a period of years to determine which of these individuals will actually develop the disease and what the relationship is between the amyloid deposits and the metabolites."
MR spectroscopy cannot currently be used for diagnosis.
Copyright: Medical News Today
Article Reference:
"Magnetic resonance spectroscopy, β-amyloid load, and cognition in a population-based sample of cognitively normal older adults"
K. Kantarci, MD, MSc, V. Lowe, MD, S.A. Przybelski, BS, M.L. Senjem, MS, S.D. Weigand, MS, R.J. Ivnik, PhD, R. Roberts, MB, ChB, MS, Y.E. Geda, MD, B.F. Boeve, MD, D.S. Knopman, MD, R.C. Petersen, MD, PhD and C.R. Jack Jr., MD
Neurology August 24, 2011, doi: 10.1212/WNL.0b013e31822dc7e1