HIV 和衰老過程概況介紹
資料來係：羅傑·佩博迪，2017 年 12 月 / aidsmap / 財團法人台灣紅絲帶基金會編
關鍵點
有時會說 HIV 會加速衰老過程，但這並不確定。
愛滋病毒感染者罹患某些健康狀況的風險更大，但不一定在年輕時。
您可以做很多事情來降低這些病症和疾病發生的風險。
衰老過程是怎樣的？隨著人們年齡的增長，身體功能的方式逐漸惡化。這些變化使老年人更容易受到感染、受傷和疾病的傷害。他們可能會失去一些精力、體力和復原力。與年輕人相比，老年人更容易罹患心臟病、糖尿病、骨質疏鬆症、癌症和其他「與年齡有關的疾病」。
由於有效的愛滋病毒治療，感染者現在的壽命比以往任何時候都長。如今，愛滋病毒感染者不太可能因為愛滋病毒而生病，但越來越多的人確實患有心臟病、糖尿病和其他「與年齡有關的疾病」。在 HIV 陽性人群中，其中一些疾病的發生率高於 HIV 陰性人群。有時，這些問題似乎發生在 HIV 感染者年輕時。
這導致許多 HIV 感染者、醫生和研究人員質疑 HIV 是否會加速衰老過程。換句話說，與同齡人相比，愛滋病毒感染者的身體機能下降並出現與年齡相關的疾病嗎？這有時被稱為「過早老化」或「加速老化」。
關於這一點，我們還有很多不知道的地方。關於過早衰老的問題尚沒有科學共識。本情況說明書解釋了為什麼某些事情目前仍然不確定，並強調了我們確實知道的四件事：
愛滋病毒感染者確實有高的比率會發生一些與年齡有關的狀況。
對這些高發的比率有幾種可能的解釋，但並非所有這些都與愛滋病毒本身有關。
你可以做很多事情來防止這些情況的發生。
總體而言，愛滋病毒感染者的健康狀況和預期壽命都非常好。
HIV感染者和未感染 HIV 的人之間的比較
需要仔細解釋有關愛滋病毒和衰老的研究結果。 HIV 陽性者和 HIV 陰性者之間的簡單比較往往會產生誤導。
首先，在年齡方面，愛滋病病毒感染者與一般人群存在較大差異。例如，雖然現在五、六十歲的愛滋病病毒感染者很多，但七、八十歲的愛滋病病毒感染者相對較少。
例如，您可能聽說 HIV 感染者被診斷患有 2 型糖尿病的平均年齡為 47 歲，而其他具有相同診斷的人的平均年齡為 54 歲。這不一定是過早衰老的證據——它僅僅是因為在最年長的年齡組中感染愛滋病毒的人數較少。未來幾年，隨著愛滋病病毒感染者年齡的不斷增長，糖尿病的平均診斷年齡可能會上升。
「愛滋病毒感染者的生活方式和生活經歷可能與普通人群不同」。
其次，愛滋病病毒感染者定期看醫生並密切監測他們的健康狀況。因此，糖尿病等疾病往往會被及時診斷出來。普通人群中的許多人只是偶爾看一次全科醫生，並且可能會在很晚才被診斷出來，當時症狀已經開始困擾他們。
第三，當研究比較 HIV 陽性和 HIV 陰性人群的健康狀況時，HIV 可能不是兩組之間唯一不同的東西。例如，常會將主要由居住在城市地區男同性戀者組成的 HIV 陽性群體與來自普通人群的樣本進行比較。
他們的生活方式和生活經歷可能在很多方面有所不同。愛滋病毒陽性人群可能更會吸煙、使用娛樂性藥物和獨居。這些因素都會對健康產生影響，但與愛滋病毒本身沒有直接關係。
為了解決這些問題，研究人員可以嘗試招募與 HIV 陽性組盡可能相似的 HIV 陰性對照組，除了沒有 HIV此一因素。例如，一些研究人員比較了感染 HIV 的男同性戀者和未感染 HIV 的同齡男同性戀者。更有可能的是，兩組的生活方式和生活經歷大致相似。
這種類型的研究也在其他團體進行過。一項特別大型且進行得很好的研究檢查了美國退伍軍人的健康狀況。其中三分之一感染了愛滋病毒，三分之二沒有。研究人員發現，如果他們在十年內觀察 1000 名 HIV 陰性退伍軍人和 1000 名 HIV 陽性退伍軍人，他們預計會看到：
13 次 HIV 陰性人群心臟病發作，平均年齡為 56 歲。
20 次 HIV 陽性者心臟病發作，平均年齡為 56 歲。
HIV 陰性人群中 74 種癌症，平均年齡為 59 歲。
HIV 陽性人群中 95 種癌症，平均年齡為 58 歲。
因此，在這項研究中，研究人員比較了具有相似生活經歷的相似年齡的人，觀察到 HIV 陰性和 HIV 陽性組都出現了健康問題。愛滋病毒感染者的患病率較高，但差異並不大。人們出現健康問題的平均年齡沒有顯著差異。研究人員評論說：「這些發現應該讓感染愛滋病毒的患者放心，他們不太可能比沒有愛滋病毒的人早幾十年經歷這些疾病」。
為什麼「與年齡有關的疾病」在 HIV 感染者中更常見？
雖然剛才提到的研究沒有發現愛滋病病毒加速衰老過程的證據，但它確實發現愛滋病毒感染者比其他人更容易罹患心臟病和癌症。無論年齡組如何，愛滋病毒感染者的患病比率都高於同齡的其他人。其他研究也發現了糖尿病、腎臟疾病、肝臟疾病、骨骼問題和其他疾病的類似結果。
有許多不同的因素可能導致 HIV 感染者出現這些健康問題的頻率更高。它們可以分為三個關鍵領域——人、免疫系統和藥物。關於每個因素的重要性存在科學爭論，但大多數專家同意這三個因素可能結合起來產生影響。
1. 人
如上所述，愛滋病毒感染者的生活方式和生活經歷可能與普通人群不同。例如，與其他人相比愛滋病毒感染者更容易吸煙並且壓力更大。由於吸煙和壓力都會導致心臟病，因此 HIV 感染者有較高的心臟病比率也就不足為奇了。
HIV 感染者的某些病毒感染率也較高，包括C型肝炎病毒、人類乳突狀病毒 (HPV) 和人類皰疹病毒第8型。在其他的事情中，這些都與 HIV 感染者更常見的癌症有關。
因此，有些與愛滋病毒沒有直接關係的事情會增加愛滋病毒感染者的健康問題風險。
2. 免疫系統
很明顯，免疫系統減弱會使健康問題和疾病的發展更有可能。 CD4 計數低的人更容易生病。此外，過去一段時間 CD4 計數非常低（例如，在他們被診斷之前）的人更有可能出現某些疾病，即使他們的 CD4 計數已經恢復。
接受愛滋病毒治療可以大大增強免疫系統並預防許多疾病，但似乎並不能完全恢復健康並逆轉所有免疫系統損傷。 HIV 可能會繼續引起持續的、低水平的炎症和免疫激活。免疫系統對 HIV 的這些功能失調的反應可能會導致廣泛的健康問題。
HIV 並不是炎症和免疫激活的唯一原因。其他病毒感染、吸煙、酗酒、吸毒、高脂肪飲食和肥胖也是促成因素。
研究表明，愛滋病毒感染者在炎症和免疫激活過程中通常會釋放大量化學物質［例如白細胞介素 6、C 反應蛋白、CD14 和 D-二聚體（interleukin-6, C-reactive protein, CD14 and D-dimer）］。除此之外，還有很多未知數。目前尚不清楚主要原因是生活方式因素、最初的愛滋病毒感染、長期感染愛滋病毒還是其他原因。科學家們不確定哪些化學物質的水平與未來更大風險的健康問題相關。
研究人員還注意到愛滋病毒感染者和老年人的這些過程之間存在一些相似之處。這一觀察結果激發了對 HIV 是否會導致「過早衰老」這一問題的大量研究。這是一個正在進行的研究領域；目前尚不清楚它的實際意義是什麼。
接受 HIV 治療仍然是限制炎症和免疫激活最重要的事情。
其他減輕炎症的藥物尚未開發出來。遵循健康生活方式的建議也將減少炎症。
3. 用藥
如果您長期被診斷出感染 HIV，幾年前您可能服用了不再推薦的抗 HIV 藥物。這些老藥中的一些現在被認為有時會對膽固醇、腎臟、肝臟和骨骼產生有害影響。
雖然所有藥物都有副作用，但現代抗 HIV 藥物更安全。今天的 HIV 治療不太可能導致 HIV 感染者出現與年齡相關的疾病。
你可以做很多事情來防止這些情況的發生
相對於與年齡相關疾病早發之不可避免的概念相反，您可以做很多事情來保護您的健康並降低這些疾病發展的風險。
接受 HIV 治療，並保持您的病毒載量無法檢測到。建議每個人立即開始 HIV 治療，但對於50 歲以上的人之疾病特別有可能預防。
定期到您的診所就診，讓工作人員監測您的健康狀況，以便及早發現任何問題。
服用他汀類藥物、血壓藥物和其他預防藥物，如果您的醫生建議。
不要吸煙。研究顯示，吸煙對愛滋病毒陽性者的預期壽命的影響比愛滋病毒更大。
限製藥物和酒精的攝入。
保持健康的體重。特別是，腹部周圍的額外的重量與更多的健康問題有關。
經常鍛煉。身體活動不僅是需要控制體重，還需要保持肌肉質量和力量。
吃得健康、均衡的飲食。
保持你的大腦活躍，用拼圖、測驗、閱讀、學習新技能或任何你喜歡的東西來刺激你的思維。
保持社交活躍。努力與朋友和家人見面，參與活動，加入俱樂部，或為慈善機構做志願者。
目前的情況
雖然未來可能發生的事情不可避免地存在不確定性，但我們可以看看愛滋病毒感染者今天的生活事實。大多數愛滋病毒感染者生活得很好，身體健康。許多 HIV 感染者從未患過任何與 HIV 相關的疾病。一些愛滋病毒感染者的健康狀況大多可以透過藥物和生活方式的改變來控制。死亡率處於歷史最低水平。根據目前的趨勢，據計算，在愛滋病毒治療第一年結束時 CD4 計數超過 350 的愛滋病毒感染者的預期壽命將接近普通人群的預期壽命。
我們在過去幾年中看到的愛滋病毒治療和照護方面的進步可能使我們變得樂觀而不是悲觀。
Factsheet HIV and the ageing process
Roger Pebody, Published December 2017
Key points
It’s sometimes said that HIV speeds up the ageing process, but this is not certain.
People with HIV are at greater risk of some health conditions, but not necessarily at younger ages.
There’s a lot that you can do to reduce your risk of these conditions and diseases occurring.
What is the ageing process? As people get older, there is a progressive deterioration in the way the body functions. These changes make older people more vulnerable to infections, injuries and disease. They may lose some of their energy, physical strength and resilience. Older people are more likely to develop heart disease, diabetes, osteoporosis, cancer and other ‘age-related conditions’ than younger people.
People with HIV are now living longer than ever, because of effective HIV treatment. These days, people with HIV are unlikely to be ill because of HIV, but increasing numbers do have heart disease, diabetes and other ‘age-related conditions’. Rates of some of these conditions are higher in HIV-positive people than in HIV-negative people. It sometimes appears as if these problems occur at younger ages in people living with HIV.
This has led many people with HIV, doctors and researchers to ask whether HIV speeds up the ageing process. In other words, do people living with HIV have a decline in physical function and develop age-related conditions at younger ages than their peers? This is sometimes referred to as ‘premature ageing’ or ‘accelerated ageing’.
There is still a lot that we don’t know about this. There is not a scientific consensus on the question of premature ageing. This factsheet explains why things are still uncertain and emphasises four things that we do know:
People with HIV do have high rates of some age-related conditions.
There are several possible explanations for these high rates, not all of them linked to HIV itself.
There’s a lot that you can do to prevent these conditions from occurring.
Overall, people with HIV have very good health and life expectancy.
Comparing people who have HIV and people who don’t have HIV
Research findings about HIV and ageing need to be carefully interpreted. Simple comparisons between HIV-positive people and HIV-negative people can often be misleading.
Firstly, in terms of age, there are big differences between the population of people living with HIV and the general population. For example, while there are now a lot of people living with HIV in their fifties and sixties, there are relatively few people with HIV in their seventies and eighties.
You might hear, for example, that the average age of a person with HIV being diagnosed with type 2 diabetes is 47, whereas the average age of other people with the same diagnosis is 54. This is not necessarily evidence of premature ageing – it is simply because there are fewer people with HIV in the oldest age groups. In future years, as people with HIV continue to grow older, the average age of diagnosis with diabetes is likely to go up.
“The lifestyles and life experiences of people living with HIV may not be identical to those in the general population.”
Secondly, people living with HIV see doctors regularly and have their health closely monitored. As a result, conditions like diabetes tend to be diagnosed promptly. Many people in the general population only see a GP occasionally and may be diagnosed much later, when symptoms have started to bother them.
Thirdly, when studies compare the health of groups of HIV-positive and HIV-negative people, HIV may not be the only thing that’s different between the groups. For example, an HIV-positive group mostly made up of gay men living in urban areas might be compared with a sample from the general population.
Their lifestyles and life experiences are likely to be different in a number of ways. The HIV-positive group may be more likely to smoke, use recreational drugs and live alone. These factors all have an impact on health but are not directly linked to HIV itself.
To deal with these problems, researchers can try to recruit HIV-negative comparison groups that are as similar as possible to the HIV-positive groups, except for not having HIV. For example, some researchers have compared gay men living with HIV and gay men of the same age who don’t have HIV. It’s more likely that the ranges of lifestyles and life experiences in the two groups are broadly similar.
This type of research has also been done with other groups. A particularly large and well-conducted study examined the health of American military veterans. A third of them had HIV and two-thirds did not. The researchers found that if they observed 1000 HIV-negative veterans and 1000 HIV-positive veterans over a ten-year period, they would expect to see:
13 heart attacks in the HIV-negative people, at an average age of 56.
20 heart attacks in the HIV-positive people, at an average age of 56.
74 cancers in the HIV-negative people, at an average age of 59.
95 cancers in the HIV-positive people, at an average age of 58.
So in this study, comparing people of similar ages who’ve had similar life experiences, the researchers observed health problems occurring in both the HIV-negative and HIV-positive groups. There are higher rates of illnesses in the people living with HIV, but the differences are not huge. And there are no meaningful differences in the average age at which people develop health problems. The researchers commented: “These findings should reassure HIV-infected patients that they are unlikely to experience these conditions decades earlier than those aging without HIV.”
Why are ‘age-related conditions’ more common in people with HIV?
Although the study just mentioned did not find evidence for HIV speeding up the ageing process, it did find that people with HIV were a little more likely to develop heart diseaseand cancer than other people. Whatever the age group, people with HIV had higher rates of the diseases than other people of the same age. Other studies have found similar results for diabetes, kidney disease, liver disease, bone problems and other conditions.
There are a number of different factors which probably contribute to the higher frequency of these health problems in people with HIV. They can be grouped into three key areas – people, the immune system and medication. There is scientific debate about how important each factor is, but most experts agree that all three probably combine to have an impact.
1. People
As mentioned above, the lifestyles and life experiences of people living with HIV may not be identical to those in the general population. For example, people with HIV are more likely to smoke and have high levels of stress than other people. As smoking and stress both contribute to heart disease, it’s not surprising that people with HIV have a higher rate of heart disease.
People with HIV also tend to have higher rates of some viral infections, including hepatitis C virus, human papillomavirus (HPV) and human herpes virus 8. Amongst other things, these are all linked to cancers which are more common in people with HIV.
So things that are not directly linked with HIV can raise the risk of health problems in people living with HIV.
2. The immune system
It’s clear that weakened immune systems make the development of health problems and disease more likely. People who have a low CD4 count are more likely to get ill. Also, people who spent some time in the past with a very low CD4 count (for example, before they were diagnosed) are more likely to develop some conditions, even if their CD4 count has since recovered.
Taking HIV treatment greatly strengthens the immune system and prevents many illnesses, but it seems that it does not fully restore health and reverse all immune system damage. HIV may continue to cause ongoing, low-level inflammation and immune activation. These dysfunctional responses of the immune system to HIV are likely to contribute to a wide range of health problems.
HIV is not the only cause of inflammation and immune activation. Other viral infections, smoking, heavy drinking, drug use, high-fat diets and obesity are also contributory factors.
Research studies show that people with HIV often have high levels of chemicals that are released by cells during inflammation and immune activation (such as interleukin-6, C-reactive protein, CD14 and D-dimer). Beyond this, much is still unknown. It’s not clear whether the main causes are lifestyle factors, the initial HIV infection, living with HIV long term or other things. Scientists are unsure exactly what levels of which chemicals are associated with a greater risk of future health problems.
Researchers have also noticed some similarities between these processes in people with HIV and in older people. This observation has stimulated much of the research into the question of whether HIV causes ‘premature ageing’. This is an area of ongoing research; it’s not yet clear what its practical implications are.
Taking HIV treatment is still the most important thing you can do to limit inflammation and immune activation.
Other medications to reduce inflammation haven’t yet been developed. Following recommendations for a healthy lifestyle will also reduce inflammation.
3. Medication
If you have been diagnosed with HIV for a long time, several years ago you may have taken anti-HIV drugs which would no longer be recommended. Some of these older drugs are now understood to sometimes have had harmful effects on cholesterol, the kidneys, the liver and the bones.
While all drugs do have side-effects, modern anti-HIV drugs are much safer. Today’s HIV treatment is less likely to contribute to age-related conditions in people living with HIV.
There’s a lot that you can do to prevent these conditions from occurring
In contrast to the idea that the early onset of age-related conditions is inevitable, you can do a lot to preserve your health and reduce your risk of these conditions developing.
Take HIV treatment and keep your viral load undetectable. Starting HIV treatment promptly is recommended for everyone but is especially likely to prevent illnesses in people over the age of 50.
Attend your clinic regularly and allow the staff to monitor your health so that any problems are picked up early.
Take statins, blood pressure medication and other preventative drugs if they are recommended by your doctor.
Don’t smoke. Studies show that smoking has a bigger impact on the life expectancy of HIV-positive people than HIV.
Limit your intake of drugs and alcohol.
Maintain a healthy weight. In particular, extra weight around your belly is associated with more health problems.
Exercise regularly. Physical activity is needed not only to control weight, but also to maintain muscle mass and strength.
Eat a healthy, balanced diet.
Keep your brain active with puzzles, quizzes, reading, learning a new skill or anything else you enjoy that stimulates your mind.
Stay socially active. Make an effort to see friends and family, get involved in activities, join a club, or volunteer for a charity.
The current situation
While there is inevitable uncertainty about what might happen in the future, we can look at the facts about how people with HIV are living today. Most people with HIV are living well and in good health. Many people living with HIV never have any HIV-related illnesses. The health conditions that some people with HIV do have can mostly be managed with medicines and lifestyle changes. Death rates are at an all-time low. Based on current trends, it is calculated that people with HIV who have a CD4 count over 350 by the end of their first year of HIV treatment will have a life expectancy approaching that of people in the general population.
The improvements we have seen in HIV treatment and care over the last few years could lead us to be optimistic rather than pessimistic.