Painless brain scans and simple blood tests may offer ways to predict who has the highest risk of Alzheimer's disease, and it may be possible to lower risks by drinking juice daily, researchers said on Sunday.

　　The occasional alcoholic drink may also help, researchers told a prevention conference sponsored by the Alzheimer's Association.

　　"There is increasing evidence that we can do something for ourselves in terms of preventing this disease," Dr. Ron Peterson of the Mayo Clinic in Rochester, Minnesota, told a news conference.

　　It is important to act early, before symptoms such a memory loss begin, the researchers added. The Alzheimer's Association estimates 4.5 million Americans have the incurable, fatal brain disease. It begins with mild memory loss and confusion and progresses gradually to a complete inability to care for oneself.

　　As many as 25 million people globally may have dementia, and those numbers will rise as the population ages.

　　"We need to be able to identify people at high risk as soon as possible," said Dr. Marilyn Alberts of Johns Hopkins University. Several studies presented on Sunday offered the possibility of predicting risk years before the disease develops.

　　Lisa Mosconi and colleagues at the New York University School of Medicine used positron emission tomography, or PET, scans to look at the brains of 53 normal elderly people.

　　They then watched for as long as 24 years to see who developed Alzheimer's. Nine did, while 19 developed mild cognitive impairment, which can worsen into Alzheimer's.

　　The PET scans detected reduced activity in an area of the brain called the hippocampus, which is known to be damaged in Alzheimer's. A 15- to 40-percent reduction in activity in the hippocampus, as measured by PET, predicted 85 percent of the Alzheimer's patients nine years in advance, Mosconi said.

　　It predicted 71 percent of the cognitive-impairment cases.

　　Alison Godbolt of the Institute of Neurology in London used a different brain scan called magnetic resonance spectroscopy in people who have a genetic flaw that makes them almost 100 percent certain to develop Alzheimer's, as well as people without the mutation.

　　The test looked for two compounds -- N-acetyl aspartate and myo-inositol and found their levels could predict which patients developed Alzheimer's.

　　美国科学家于6月19日表示，无痛的脑部扫描以及简单的血液检测能够为预测老年痴呆症的高危人群提供方法。研究人员还同时表示，每天饮用适量的果汁也可能会降低这一病症发生的危险。

　　据路透社网站6月20日报道，研究人员是在一个由美国老年痴呆症研究协会发起的预防会议上发表上述观点的。他们还表示，偶尔饮酒对预防老年痴呆症可能也会有所帮助。

　　对此，美国明尼苏达州罗彻斯特梅约医学中心(Mayo Clinic)的朗·彼得森教授表示：“越来越多的证据显示，现在在预防这一疾病的问题上，我们可以为自己做些什么了。”他还说，在一些症状(如开始丧失记忆力等)出现之前，及早行动非常重要。

　　据美国老年痴呆症研究协会估计，目前大约有450万美国人患有这种不能治愈的、危害极大的脑部疾病。这种病症的早期症状是轻度的记忆力丧失和意识混乱，后来逐渐发展成个人生活完全不能自理，要靠别人照顾。在全球范围内，大约有2500万人患有这种疾病，随着人口老化，这一数字还将有所增加。

　　在这种情况下，对老年痴呆症及早发现和预防工作就显得尤为重要。美国纽约大学医学院的莉萨·墨斯科尼和其同事使用正电子发射断层成像(Positron Emission Tomography, PET)技术，对53名正常的中老年人进行了脑部扫描。而后，对这些人被观察了24年之久，看谁会受到老年痴呆症的困扰。

　　研究结果显示，在这些被调查者中有9人最终患上了此疾病；另外有19人有轻微的认知损伤，而这一症状则可恶化为老年痴呆症。PET扫描发现了脑部一个名为海马状突起(大脑侧面脑室壁上的隆起物，主要由灰白质构成，在泛记过程中起主要作用)的区域活性减弱的现象。而据人们所知，这一区域会因为受到老年痴呆症影响而被破坏。墨斯科尼说，由PET扫面测定出的该区域活性减弱15%至40%，可以提前9年预测出85%的老年痴呆症患者，同时还能预测71%的认知损伤病例。

　　伦敦神经学研究所的艾莉森·格特波特使用了另外一种名为磁共振波谱分析(Magnetic Resonance Spectroscopy, MRS)的脑部扫描方法对这一课题进行了研究。格特波特发现，两种化合物——N-乙酰天冬氨酸盐(N-acetyl aspartate)和肌醇(myo-Inositol)的水平可以预测出谁会患上老年痴呆症。