为什么治疗痴呆如此困难

为什么治疗痴呆如此困难

Finding a cure for neurodegenerative diseases such as Alzheimer's is challenging. They're difficult to diagnose, and drugs struggle to get into the brain as the brain's blood supply is largely separate to the rest of the body.

寻找治疗阿尔茨海默症等神经退行性疾病的方法是一项挑战。它们很难被诊断，而且由于大脑的血液供应在很大程度上与身体的其他部分分离，药物很难进入大脑。

Not surprisingly, several companies have left this territory in recent years. Last week, pharmaceutical giant Pfizer announced it will stop research into developing drugs to treat Alzheimer's disease, after costly failed attempts over the past decade.

毫不奇怪，近年来有几家公司已经离开了这一领域。上周，制药巨头辉瑞公司宣布将停止研发治疗阿尔茨海默氏症的药物，在此之前的10年里，辉瑞公司付出了巨大的代价，但都以失败告终。

In recent years some clinical trials involving potential dementia drugs have had disappointing setbacks. In 2012, Pfizer and Johnson & Johnson halted development of the antibody drug bapineuzumab, after it failed in late-stage trials to treat patients with mild to moderate Alzheimer's.

近年来，一些涉及潜在痴呆药物的临床试验出现了令人失望的挫折。2012年，辉瑞公司和强生公司停止了抗体药物bapineuzumab的研发，因为它在治疗轻度至中度阿尔茨海默病的后期试验中失败。

So what makes dementia such a difficult condition to treat with drugs, and is progress being made towards a treatment?

那么，是什么让痴呆症难以用药物治疗呢?治疗的进展如何呢?

Why dementia is so hard to treat
为什么痴呆如此难以治疗

Despite the vast number of people affected globally, with an estimated 46.8 million peoplecurrently living with dementia, there is currently no cure. While current treatments manage symptoms (the latest drug to gain FDA approval was memantine, in 2003) they offer no prospect of recovery.

尽管全球受影响的人数众多，目前估计有4680万人患有痴呆症，但目前尚无治愈方法。虽然目前的治疗可以控制症状(2003年获得FDA批准的最新药物是美金刚胺)，但它们没有治愈的希望。

Part of the difficulty in finding treatments for dementia stems from the fact it's not a single disease, but a complex health problem with more than 50 underlying causes. Dementia can be better thought of as an umbrella term describing a range of conditions that cause parts of the brain to deteriorate progressively.

寻找治疗痴呆症的方法之所以困难，部分是因为它不是单一的疾病，而是一个有50多种潜在原因的复杂健康问题。痴呆症可以被更好地理解为一个概括性术语，它描述了一系列导致大脑部分逐渐退化的情况。

Most drug treatments currently in development have targeted the pathology of Alzheimer's disease, the most common form of dementia, which accounts for about 60 to 70% of all cases.

目前正在开发的大多数药物治疗都针对阿尔茨海默氏病的病理学。阿尔茨海默氏病是痴呆症最常见的一种，约占所有病例的60 - 70%。

Finding a successful treatment for Alzheimer's faces two major hurdles: the first being we still don't know enough about the disease's underlying biology,or why the disease progresses at different rates in different people.

找到治疗阿尔茨海默氏症的成功方法面临着两大障碍:第一，我们仍然对这种疾病的潜在生物学知之甚少，也不知道为什么不同的人的病情发展速度不同。

It doesn't help that symptoms of Alzheimer's develop gradually and slowly and a diagnosis might only be made years after the brain has started to undergo neurodegenerative changes.

阿尔茨海默症的症状发展缓慢，可能只有在大脑开始发生神经退行性变化数年后才会做出诊断，这一点也没有帮助。

The second major hurdle to finding a treatment is that drugs need to first cross the blood-brain barrier. The blood-brain barrier provides a defence against disease-causing pathogens and toxins that may be present in our blood, and by design exists to keep out foreign substances from the brain. The downside is that it also keeps the vast majority of potential drug treatments from reaching the brain.

寻找治疗方法的第二个主要障碍是，药物必须首先穿过血脑屏障。血脑屏障为我们抵抗可能存在于血液中的致病病原体和毒素提供了一种防御机制，它的存在是为了阻止外来物质进入大脑。它的缺点是，它还阻止了绝大多数潜在的治疗药物到达大脑。