Hear better, sleep better, think better: What physicians should know about dementia risk

It appears hearing and sleep are two factors that could affect how people develop dementia, including Alzheimer’s related dementia, later in life.

Two researchers from met online with news media to discuss the latest findings on dementia, Alzheimer’s disease, and ways to protect and preserve brain health. It has a human cost for the 5.6 million people living with dementia, and their families, and a financial one: $781 billion in 2025, according to an estimate supported by the National Institute on Aging.

Jennifer Anne Deal, Ph.D., M.S., is an associate professor in the Department of Epidemiology and co-director of the Epidemiology Doctoral Program at the Johns Hopkins Bloomberg School of Public Health. Adam Spira, Ph.D., M.A., is a professor in the department of mental health at the Johns Hopkins Bloomberg School of Public Health and core faculty at the Johns Hopkins Center on Aging and Health.

This FAQ presents summaries of their introductory remarks and questions submitted by Medical Economics and other news outlets. This transcript has been edited for length and clarity.

Jennifer Anne Deal, Ph.D., M.S.: Hearing loss is common with aging and affects clarity more than volume — words blur together rather than simply sounding quieter. Public health research consistently links hearing loss to higher dementia risk, though a causal relationship has not been established. Hearing loss may affect the brain directly and contribute to social isolation, both of which are potential pathways to cognitive decline.

In a large randomized controlled trial, participants received either a hearing intervention, including hearing aids and counseling, or a health education control program and were followed for three years. Overall, hearing treatment did not reduce cognitive decline. However, among a higher-risk subgroup, older participants with more comorbidities such as hypertension and diabetes and lower baseline cognitive scores, hearing treatment did appear beneficial. For all participants, hearing treatment improved communication, reduced loneliness and reduced social isolation. Researchers cautioned that population-level findings reflect averages, not individual outcomes.

Adam Spira, Ph.D., M.A.: Sleep disturbances, including insufficient sleep, poor sleep quality and fragmented sleep, are now considered risk factors for cognitive decline and dementia. Certain sleep disorders, such as obstructive sleep apnea (OSA), may also increase dementia risk, including Alzheimer's disease dementia.

Earlier research focused primarily on how brain changes associated with dementia cause sleep disturbances. More recent work has shifted attention to the reverse: whether sleep disturbances in otherwise healthy people can lead to brain changes that cause dementia. While definitive causal evidence in humans is lacking, animal studies show that sleep deprivation produces Alzheimer's disease-related brain changes, providing meaningful support for a causal link.

Sleep disturbances are common in older adults, but effective treatments exist across all stages of life. This makes disturbed sleep a potentially modifiable risk factor, and a promising target for interventions aimed at preserving brain health and reducing dementia risk later in life.

What is the best advice or recommended resources for primary care physicians working with patients or their family members who are showing early signs of Alzheimer's disease?

Jennifer Anne Deal, Ph.D., M.S.: There is published guidance from the National Institutes of Health, as well as the Alzheimer's Association. This guidance really does try to understand and recognize that primary care providers are key in terms of the care for individuals who have dementia, as well as for involving their family caregivers, and not just a triage point. So, these recommendations broadly move beyond just things like testing and diagnosis to really, really highlight, again, the importance of the care that primary care physicians can provide. Some examples for general guidance include reviewing medications, as some medications can cause cognitive decline and impairment; talking about potential risk factors, and reviewing medications for risk factors; as well as additional counseling, so things like hypertension and diabetes, for example. Safety planning is something where primary care physicians can have important conversations with family, making sure that caregivers are engaged as well. And advanced care planning is another topic that is often recommended where primary care physicians can really play an important role.

Dementia and Alzheimer's disease has been with humankind for donkey’s years. What is the new thinking about prevention that populations everywhere should be aware of?

Adam Spira, Ph.D., M.A.: One way to summarize the way that people are thinking about dementia and Alzheimer's disease risk these days is that it is not one single factor that is contributing to that risk. There are a whole range of factors that play a role, ranging from we've been talking about, hearing loss and sleep disturbances. But they include other things like card metabolic problems, cardiovascular risk factors like hypertension, diabetes, metabolic problems like obesity, depression, traumatic brain injury. There are many other factors that we believe play an important role. Physical activity is another one. But there are many that are involved, and it is unlikely to be effective right now to, if one focuses solely on one, we think, for the general population.

Do you think wearable devices that track sleep quality, like the rings or watches, for example, are a helpful tool to manage sleep disturbances that affect brain health? Or do these tools not go far enough?

Adam Spira, Ph.D., M.A.: There are studies that are using those devices to track sleep and circadian rhythms and physical activity. Another important dementia risk factor is physical inactivity. But those devices are not yet really ready to be used as biomarkers, if you will, of dementia risk on their own. We are using them to study sleep and physical activity. More often than not we use research-grade devices rather than the commercially available ones, although I will say that the commercially available ones have gotten quite good, and researchers are now employing them a lot. So I guess if the question is to track risk, we certainly do use devices like that in our research, but we have to be cautious when recommending — we don't want people to interpret the results from their commercially available devices and decide that they are doomed to get dementia. That is not the way that we want people to think about it.

What is Alzheimer's disease, and how is it different from dementia?

Adam Spira, Ph.D., M.A.: That's a great question and it's a source of confusion for a lot of people. So, dementia refers to a significant, a really significant decline in cognitive function, in thinking and memory, in at least one domain, usually more, of thinking and memory that represents a change from a prior level of functioning, obviously, and leads to really significant impairment in daily functioning. There are many different pathways that can lead to dementia, including Alzheimer's disease, which is the most common cause of dementia, I should mention there are other causes, like vascular contributors to dementia, that are really important to consider. But Alzheimer's disease is characterized by really two things that happen in the brain. The first is, in earlier stages of the disease process, and I should note that this phenomenon that I'm describing actually begins decades potentially before the onset of any measurable cognitive decline, but the aggregation of beta amyloid protein into amyloid plaques in the brain is the first defining feature of Alzheimer's disease. And the second is intraneuronal, within neurons you see neurofibrillary tangles, or tau protein, that is misfolded in the brain cells. Those are the two neuropathological features that are that define Alzheimer's disease. But like I said, there are many different ways that one can end up with a dementia diagnosis, with Alzheimer's disease being the most common.

The Lancet Commission offers policymakers clear policies aimed at reducing age-adjusted prevalence of dementia, of which correcting hearing loss is cost-effective. Do the panelists have a view of other, i.e. not related to the Commission, policies worth pursuing or investigating, such as vaccination against herpes zoster, based on Pascal Geldsetzer's work, or any other policies?

Jennifer Anne Deal, Ph.D., M.S.: The Lancet Commission certainly is a very important publication in our work. It really tries to understand what proportion of dementia risk across the globe could we potentially address if we try to address all of the modifiable risk factors for dementia, so the things that we can actually change. I do just want to highlight a point Dr. Spira made earlier, which is at this point we recognize there's probably no one magic bullet for dementia prevention. We really need to probably be tackling a number of different factors in order to move the needle. Something like hearing loss in the Lancet Commission is associated with 7% of dementia cases worldwide, potentially due to hearing loss. As with all other risk factors that are discussed in that report, there are some really important caveats to the interpretation of that number, and so we have to assume that whatever factor we're talking about, that factor actually causes dementia. For some of these factors, I think we have a lot of really good evidence, so things like hypertension, lowering blood pressure can be very beneficial for the brain. I certainly do believe that hearing loss is something that we should be pursuing, but I do just want to highlight again, we are not at the stage yet where the research has definitively proven that hearing loss causes dementia, or if we treat hearing loss with hearing aids, for example, that we can prevent dementia cases from occurring. We need some additional research here, but I think my main point and comment I would just like to emphasize for this question is, it's probably just not one thing. We probably have to really be thinking from a policy standpoint how we can address all of these factors if we really want to move the needle on dementia prevention.

What can people do to protect their brain health, particularly as they age?

Jennifer Anne Deal, Ph.D., M.S.: We need to be taking multiple steps if we want to be protecting our brain health. And the good news is that there probably is really a lot within our control. Some factors that we do have control over to protect our brain: We want to take care of our heart in order to take care of our brain, just like Dr. Spira mentioned earlier. Things like hypertension, diabetes, obesity, these are all things that we can address that are important for brain health. I say, don't ignore your hearing. We're still trying to learn how hearing loss may impact dementia risk over time, but we do know it's really important for social engagement and for communication every day, and we also know that those things are also really important to help prevent dementia. Remaining socially engaged is really important for both your heart and your brain. Some other things that are really important: smoking and drinking. If you are able to do less of both, the evidence suggests that that is better for your brain as well.

How can you tell if a person is having normal age-related memory loss versus dementia?

Jennifer Anne Deal, Ph.D., M.S.: The key thing is, is it impacting everyday life? We all tend to forget things as we age. There are a lot of issues like that — where we put our keys, for example. Things like that are very common. What we would be concerned about is if someone is starting to show a lot of change that is different from the way that they used to be able to remember things. For example, misremembering an entire conversation that recently happened, that would be concerning, but just misremembering or not being able to remember certain components of that conversation would be completely normal, something like getting lost in a familiar place would be something again we might be concerned about, or asking the same question repeatedly without remembering that the question had been asked before. Sometimes we can see personality changes also that can start to indicate that maybe something more is going on than just the standard declines we might see in normal aging, or if we're unable to orient ourselves in the way that we used to be able to, so not knowing what place we're in, what season, or what time, things like that. The key is for any of this that it, the cognitive decline does have to be severe enough to impact everyday life, and for a diagnosis, or with any concerns, the key really is to reach out to a clinician or talk to a doctor. There are some tests that can be conducted, and importantly, there are some potentially reversible causes for cognitive changes. For example, in older adults, sometimes even something like a urinary tract infection can lead to cognitive changes. So, if there's any concerns, the most important thing is to reach out to a physician.

Why is sleep so important for your overall health?

Adam Spira, Ph.D., M.A.: Sleep is connected to everything. Every organ system is affected by sleep. The American Heart Association really added adequate sleep to its what used to be Life's Simple Seven is now Life's Essential Eight, and sleep is one of those, because it has it's really clearly linked to poor cardiovascular health outcomes. The AHA, also issued a statement on the implications of sleep disturbance for brain health. The cardiovascular route is a really important. We know that what's good for your vascular health is good for your general health, but sleep is also an important modulator of immune function. You're less likely to get a cold, if you're getting adequate sleep, we know that it helps with recovery from illnesses. It's a key component of some mental disorders, and can be a precipitant of some of those mental disorders, particularly mood disorders, so, it's important from that perspective. It's been linked to so many different aspects of physiology that I think it's important to focus on sleep. Again, we don't have as much causal evidence as we would like, that's tough to get in humans, right? But we have so much evidence linking sleep to a range of health outcomes, particularly in older people, we're seeing more and more research every day, but across the life course too.

I had a parent who died of complications from dementia, although my grandparents did live much longer. What are the best ways for me to protect my brain?

Jennifer Anne Deal, Ph.D., M.S.: Family history, we know, is a risk factor for dementia. But I think it's also recognized that it's not a full determinant. I have a family history of dementia as well. In my family, it does increase risk. The most common gene that we know of is Apolipoprotein E4 and individuals who have a copy of that have an increased risk of dementia equivalent to about 20% to 25% compared to people who do not have that allele, but again, it's not just having that allele that's going to lead to dementia having it. So the key thing is to take care of everything else that's within your control, so again it's things like taking care of your heart, managing your medications, making sure that we're limiting alcohol intake, smoking cessation if it's there, taking care of your hearing, making sure that we're staying active, physically active, also very socially active out there, and getting engaged with others and really connecting with the world. All of these things are within our control, and so these are all things that are good for us. It's good to start as soon as possible. Dr. Spira mentioned earlier that the pathology in the brain for Alzheimer's disease starts building up, maybe 20 years or so, even before we start to see cognitive changes. So that means that our midlife health is really important. But I think another really important message is that it's not too late, it's never too late. So, no matter what age we are, we can still start taking control of other factors in our lives.