Dementia Prevention: Genetics, Hearing Loss, and the Factors Most People Miss
Dementia is one of the most feared diagnoses in medicine, and with good reason. It is progressive, it is personal, and for most of its history it has felt largely beyond our control. That perception is changing. A growing and increasingly robust body of evidence suggests that nearly half of all dementia cases may be preventable by addressing factors within our control. That is an extraordinary finding, and one that deserves far more attention in conversations about longevity and long-term brain health.
This post is about what we actually know, what remains uncertain, and where the most meaningful opportunities for prevention lie.
The Genetics Question: Who Should Be Tested and Why
Patients frequently ask about genetic testing for dementia risk, and the answer requires some nuance. There are two meaningfully different conversations to have here.
The first involves families with a history of early-onset dementia, typically defined as dementia presenting before age 65. In these cases, testing for rare mutations such as those in the APP, PSEN1, or PSEN2 genes is clinically appropriate and can provide important information for both the patient and their family. This is targeted testing for a specific, elevated-risk population.
The second conversation involves population-level screening using the ApoE gene, specifically the ApoE4 allele, which is the strongest known genetic risk factor for late-onset Alzheimer's disease. This is where my thinking is less settled, and I want to be transparent about that. Carrying one copy of ApoE4 increases lifetime risk meaningfully; carrying two copies increases it substantially more. Knowing this can be useful: it can inform how aggressively to pursue modifiable risk factors, particularly lipid management, given that high LDL cholesterol was added to the Lancet Commission's list of modifiable dementia risk factors in 2024.
For individuals who are not prone to clinical anxiety, knowing they carry the allele may provide motivation to take prevention more seriously. For those who are, however, I approach ApoE4 screening with considerably more caution. There is currently no approved treatment that specifically targets ApoE4-related risk, and for anxiety-prone patients, an abnormal result can produce lasting fear that diminishes quality of life without a clear clinical benefit to offset it. This is a conversation worth having with your physician, with careful consideration of your own temperament and how you tend to process uncertain risk information.
The Modifiable Risk Factors: Where the Real Opportunity Lies
The 2024 report of the Lancet Commission on Dementia Prevention, Intervention, and Care identified 14 modifiable risk factors that collectively account for approximately 45% of global dementia cases. That figure is striking. It means that nearly half of all dementia may be attributable to factors we can actually address, across every stage of life. Below are the ones I consider most important for the patients I work with, including several whose connection to brain health is less obvious than it should be.
Hearing Loss: The Most Underappreciated Risk Factor in the Room
Of all the modifiable risk factors on the Lancet Commission's list, hearing loss may be the one that surprises people most. A 2025 meta-analysis found that moderate hearing loss increases dementia risk by 29% and severe hearing loss by 49%, based on objective audiometry measurements. A separate meta-analysis found that hearing aid use may reduce the rate of cognitive decline by 19%. The ACHIEVE trial, a rigorous randomized controlled trial published in The Lancet in 2023, found that a hearing intervention reduced cognitive decline in high-risk older adults with untreated hearing loss.
The mechanisms are not fully established, but the leading theories involve cognitive load and social withdrawal. When hearing deteriorates, the brain expends increasing resources simply to decode speech, diverting capacity from other cognitive functions. Simultaneously, the frustration and embarrassment of not hearing well tends to drive social withdrawal, which is itself an independent dementia risk factor.
Despite this evidence, many patients resist hearing aids. The reasons are almost always social: hearing aids feel like a visible marker of aging, a concession they are not ready to make. This perception deserves to be challenged directly. Modern hearing aids are remarkably discreet, comfortable, and technologically sophisticated. Many are nearly invisible when worn. The calculus is simple: the cosmetic concern about wearing a hearing aid is trivially small compared to the potential cognitive cost of leaving hearing loss unaddressed. If you have noticed difficulty hearing in conversations, particularly in noisy environments, please have your hearing evaluated.
Vision Loss: The Newly Recognized Risk Factor
The 2024 Lancet Commission update added untreated vision loss as a new modifiable risk factor for dementia, based on evidence from two large meta-analyses. The parallel with hearing loss is direct: both involve sensory deprivation that increases cognitive load and social isolation. Cataracts, macular degeneration, and other correctable or manageable conditions deserve timely attention not just for quality of life, but for long-term brain health.
Social Engagement and Intellectual Stimulation
Social isolation appears on the Lancet Commission list as a significant modifiable risk factor, and the evidence behind it is substantial. Human beings are neurologically social creatures. Sustained, meaningful social engagement appears to build cognitive reserve, the brain's resilience against the structural changes of aging. This is particularly relevant for high-performing individuals who have retired from demanding professional careers. The cognitive stimulation that came built into an active professional life does not disappear gradually; for many people it stops abruptly, and replacing it requires deliberate effort.
The research does not suggest that any single activity is uniquely protective. What appears to matter is continued intellectual engagement: learning new skills, maintaining complex social relationships, pursuing activities that require sustained mental effort. For my patients who are retired or approaching retirement, I consider this as important a conversation as any medication review.
Vascular Health: Blood Pressure and Cholesterol
Hypertension has been on the Lancet Commission's risk factor list for years. The 2024 update added high LDL cholesterol, supported by evidence from large cohort studies involving more than one million participants. The vascular connection to dementia is well established: what is bad for the heart is generally bad for the brain. Sustained elevation of blood pressure and cholesterol damages the small vessels that supply the brain, contributing to vascular dementia and likely accelerating Alzheimer's pathology as well. Aggressive management of both, particularly in midlife, is among the most evidence-based things we can do for long-term brain health. In a personalized medicine context, this is exactly the kind of risk factor that warrants proactive monitoring rather than waiting for symptoms to appear.
Sleep
Sleep does not appear on the Lancet Commission's formal list, but the evidence connecting poor sleep to dementia risk is growing rapidly and warrants serious attention. During deep sleep, the brain's glymphatic system clears metabolic waste products, including amyloid beta, the protein associated with Alzheimer's disease. Chronic sleep deprivation and untreated obstructive sleep apnea both impair this clearance process. Sleep apnea is particularly relevant for the patients I see in concierge and executive health settings, as it is common, frequently undiagnosed, and highly treatable. If you snore, wake unrefreshed, or experience daytime fatigue, a sleep study is worth pursuing.
Depression
Depression has a complex and bidirectional relationship with dementia. It is both a risk factor and an early symptom, which makes the relationship difficult to disentangle. What is clear is that untreated depression is harmful to brain health, and that high-functioning individuals frequently minimize or dismiss depressive symptoms that would benefit from treatment. This is a population in which depression is often underdiagnosed precisely because external performance remains intact for longer.
Physical Activity
Physical inactivity is on the Lancet Commission list, and the evidence is consistent across decades of research. Exercise increases cerebral blood flow, promotes neurogenesis, reduces inflammation, and improves sleep quality, making it one of the few interventions that addresses multiple dementia risk factors simultaneously. Resistance training and aerobic exercise both appear to contribute, which reinforces the case for a well-rounded fitness approach rather than optimizing for one modality alone.
The Bigger Picture
Dementia prevention is not a single intervention. It is a lifelong accumulation of decisions about how we treat our bodies, our minds, and our relationships. The evidence from the Lancet Commission tells us that nearly half of all cases may be within our reach to prevent, not through any single medication or technology, but through sustained attention to factors that are available to all of us.
For patients who want to understand their genetic risk, that conversation is worth having thoughtfully and in the right context. But genetics sets a predisposition, not a destiny. The most powerful tools we currently have for protecting the aging brain are the ones whose connection to brain health is least obvious: treating hearing and vision loss, staying socially and intellectually engaged, managing vascular risk factors, sleeping well, and moving consistently. These factors are receiving increasing attention in the research community, and rightly so. The evidence behind them is as solid as anything in preventive medicine, and acting on them does not require waiting for a diagnosis.
Dr. Schraga is a concierge physician and the founder of Crescendo MD, a longevity-focused concierge medicine practice serving the San Francisco Bay Area. He specializes in personalized preventive care, executive health, and longevity medicine for high-performing individuals and families.
