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USNEWS：与年龄相关的睡眠问题和记忆丧失
最新临床试验：奥比妥珠单抗联合或不联合乌姆拉西布、来那度胺或联合化疗治疗复发或难治性I-IIIa级滤泡性淋巴瘤
2018年12月20日
德克萨斯儿童医院（Texas Children’s Hospital, Houston, Texas）
2018年12月21日
By Michael O. Schroeder
本篇文章是关于老年人的睡眠困难的问题。现在的研究已经表明，睡眠困难可能会损害认知功能，并可能增加患阿尔茨海默病的风险。作者在这里引用相关医学专家的研究成果，说明即使从短期来看，睡眠不足或睡眠质量差都会使人们无法发挥出最好的精神状态，无论是更复杂的执行功能，还是解决问题或记忆。研究人员、临床医生和护理人员都知道痴呆会引起睡眠障碍。但是，越来越多的证据表明，睡眠问题可能与年龄有关，尤其是当这些睡眠问题持续存在或慢性时，睡眠问题更常见，并且与罹患进展性脑病阿尔茨海默病和其他类型痴呆的风险增加有关。失眠或睡眠呼吸暂停会抑制一个人在睡觉时正常呼吸的能力，是发展为痴呆的危险因素。关于睡眠问题是否或如何影响一个人经历长期认知衰退的机会还有很多不清楚。总之，如何促进睡眠质量，已经成为神经学科新的重点研究方向之一。下面我们就来读一下原文。
EVEN IN THE SHORT TERM, not getting enough sleep or poor quality zzz’s can keep people from performing at their mental best, whether it be more complex executive functioning or problem-solving or memory. The experience is universal – we’ve all had it: “We have a bad night’s sleep, we’re hazy in the morning, we may not be as sharp as we usually are,” says Michael V. Vitiello, a professor of psychiatry and behavioral sciences and geriatrics at the University of Washington School of Medicine. “We may have some lapses in memory or we don’t process information quite as well.”
What’s more, it’s well-known by researchers, clinicians and caregivers that dementia can cause sleep disturbances. But, increasingly, evidence indicates that there may also be a link between sleep problems, which are more common with age – particularly when those sleep issues are persistent or chronic – and an increased risk of developing the progressive brain disorder Alzheimer’s disease and other types of dementia. Having insomnia or sleep apnea – which inhibits a person’s ability to breathe normally while sleeping – are risk factors for developing dementia.
Much still remains unclear in regards to whether or how sleep problems might impact one’s chances of experiencing long-term cognitive decline. Research hasn’t yet established, for example, that persistent sleep woes cause or contribute to the development of dementia later in life, Vitiello and others emphasize. But experts say that emerging data has provided at least a theoretical framework for why the two may be related – and suggest the relationship could be bi-directional: that not only can dementia disrupt sleep, but that not getting adequate, quality rest may raise dementia risk. What’s more, close study even provides a peek into the brain to possibly explain what might be behind the association.
One of the neural hallmarks of Alzheimer’s is the buildup of protein pieces called beta-amyloid, that come from the fatty membrane which surrounds nerve cells in the brain. Plaques in the brain form when bits of beta-amyloid clump together, according to the Alzheimer’s Association. “The small clumps may block cell-to-cell signaling at synapses. They may also activate immune system cells that trigger inflammation and devour disabled cells.”
Generally speaking, sleep – especially of the deeper more restful variety – is restorative. Even from an experiential standpoint, most people can understand that sleep can help us collect our thoughts, and serves an organizational function; you might “sleep on it” when making a big decision. But it goes deeper than that.
“There’s been a lot of research recently suggesting that during sleep there’s a physiological mechanism by which amyloid perhaps is cleared from the brain and allowed to be filtered out of the central nervous system and removed,” says Dr. Arjun Masurkar, an assistant professor of neurology and neuroscience and physiology at NYU Langone Health’s Alzheimer’s Disease Center in New York City. “It would lead to the intriguing idea that the better you sleep, the better you clear amyloid from your brain, and that perhaps poor sleep will retain amyloid in the brain and therefore lead to Alzheimer’s disease.”
There’s reason to think that the problem could be cyclical too – that as amyloid-beta, or Aβ, builds up, even before a diagnosis of dementia, it can disrupt sleep, allowing Aβ to build up even more. As asserted in a 2014 opinion in Nature Reviews Neurology, “evidence is emerging that the sleep–wake cycle directly influences levels of Aβ in the brain. In experimental models, sleep deprivation increases the concentration of soluble Aβ and results in chronic accumulation of Aβ, whereas sleep extension has the opposite effect.” Experts say more sleep – and particularly restful, deeper slumber, seems to help to “clean” or clear these buildups, which are found in brains of people with Alzheimer’s disease.
“Once Aβ accumulates, increased wakefulness and altered sleep patterns develop. Individuals with early Aβ deposition who still have normal cognitive function report sleep abnormalities, as do individuals with very mild dementia due to AD,” the opinion continues. “Thus, sleep and neurodegenerative disease may influence each other in many ways that have important implications for the diagnosis and treatment of AD.”
As a person ages, it’s common to experience change with your circadian rhythm, essentially the 24-hour clock that controls your sleep-wake cycle. “In older people especially, problems such as difficulty falling and staying asleep are common, and sleep patterns also shift due to alterations in circadian rhythm,” the National Sleep Foundation explains.
“Most people spend much of their lives with a circadian rhythm that ticks along at an even, healthy pace. Later in life, however, this internal clock can begin to lose its consistency. As a result, older adults sleep fewer hours,” the NSF notes. “They often become tired earlier in the evening than they used to, while waking up earlier in the morning. They also may experience a decline in cognitive function during the evening.”
To compound difficulties, that natural propensity to hit the hay earlier and get up earlier as well often doesn’t jibe with social schedules, work obligations or choices to stay up late for other reasons. “Obviously, for some older adults that doesn’t necessarily align with their personal and social lives,” says Alyssa Gamaldo, an assistant professor of human development and family studies at Penn State University.
In her own research, Gamaldo has explored the causes and potential implications of disparities in sleep problems among minorities, including African-Americans. Older adult minorities – as well as their young adult counterparts – typically report getting less sleep and lower quality sleep, she says, in addition to a higher incidence of insomnia and sleep apnea, compared with older white adults.
There are many possible reasons for this. Research indicates social factors like socioeconomic status and financial strain and health factors, such as higher rates of heart disease and diabetes in blacks, may play a role, and “those diseases being associated with sleep disruptions,” Gamaldo says.
Some of these same health problems have been associated with a higher rate of dementia. What’s more, ongoing sleep problems can raise a person’s risk for depression, and make it harder to maintain a healthy lifestyle that could also lower one’s risk of dementia. “When you’re not sleeping well, you’re not socially active, you’re not physically active,” and it affects diet, says Joseph Dzierzewski, an assistant professor of clinical psychology at Virginia Commonwealth University. “All of these things – all these lifestyle factors as well – are related to onset and development of Alzheimer’s disease.”
Experts reiterate that it’s still exceedingly difficult – if not impossible – to tease out the chain of influence, and whether or how sleep problems may ultimately raise one’s chance of developing long-term cognitive deficits. But what shouldn’t be missed, say clinicians and researchers, is that despite the common nature of sleep disruption with age, older adults shouldn’t resign themselves to being up all night, or sleepy all day.
“What we can say is that there’s good evidence that poor sleep impacts lots of things over time including cognitive function, and the better you sleep, the better off your general health is going to be and probably your cognitive function is going to be,” Vitiello says. Experts say while changes occur over a person’s lifespan that may impact sleep quality, older adults can still sleep well.
In fact, there’s lots that an older person can do to rest easier:
- Follow basic sleep hygiene practices. Keep a consistent schedule, make sure your room is cool and dark, don’t consume caffeine in the evening before bed and turn off screens as least an hour before bedtime. “There’s this misconception that older adults are not using technology,” Gamaldo says. “But right now we’re actually seeing that’s not necessarily true.”
- Get snoring checked out. If you’re sawing logs – something that’s more common in older sleepers – you should let your doctor know to determine if a more significant problem like sleep apnea is to blame. The same goes with disclosing insomnia or any sleep problems to a doctor to get necessary medical attention – and get back to bed.
- Check your medicines. Older adults often take more medications. And a number of drugs – from beta blockers to control high blood pressure and anti-arrhythmic meds for heart rhythm problems, to selective serotonin reuptake inhibitors, or SSRIs – can affect a person’s ability to sleep, the National Sleep Foundation notes. Ask about side effects related to sleep and alternative options as needed and based on what’s available.
- Treat pain. Back pain and other sources of discomfort are more common with age and can be highly disruptive to sleep. Although often there’s no quick and fast (or even any) cure, addressing the issue, and at least lessening pain, can significantly improve sleep.
- Don’t let your lifestyle slip. It might be tempting to eat whatever and exercise whenever (or not at all), but doing so can be a double whammy, torpedoing not only overall health, but making it harder to fall asleep promptly and rest soundly. On the contrary, there’s nothing like hitting the pillow after an active day.
Taken together, experts say, making necessary lifestyle changes and seeking medical attention as needed can go a long way toward sleeping well at any age.
