Dementia Prevention: What the Latest Research Tells Us, and What You Can Actually Do About It

For most of medical history, dementia has been treated as something that simply happens. You either develop it or you do not, and there is not much to be done in between. That view is no longer defensible. The 2024 Lancet Commission on Dementia Prevention identified 14 modifiable risk factors that together account for nearly 45% of global dementia cases. Nearly half. That figure reframes dementia not as an inevitable feature of aging, but as a condition with meaningful opportunities for prevention across the entire course of a person's life.

At Crescendo MD, brain health and cognitive longevity are central to how we think about care for our patients on the San Francisco Peninsula. What follows is an honest account of what the evidence supports, where uncertainty remains, and which factors deserve the most attention.

Should You Get Genetic Testing for Dementia Risk?

This is one of the questions we hear most often, and the answer depends entirely on why you are asking.

For patients with a family history of early-onset dementia, meaning dementia that presented before age 65, genetic testing is clinically appropriate. Mutations in the APP, PSEN1, and PSEN2 genes are rare but carry significant implications, and identifying them provides information that is genuinely actionable for the patient and their family. This is a different conversation from general population screening.

The more common question involves the ApoE4 allele, the strongest known genetic risk factor for late-onset Alzheimer's disease. Here, my position is nuanced. Carrying one copy of ApoE4 meaningfully increases lifetime risk; carrying two copies increases it substantially more. For patients who process uncertain information well and are motivated by data, knowing their ApoE status can be useful. It provides a rationale for being especially aggressive with modifiable risk factors, particularly lipid management, which gained additional support in 2024 when the Lancet Commission added high LDL cholesterol to its list of modifiable dementia risk factors.

For patients who are prone to anxiety, however, I approach ApoE4 testing with considerable caution. There is currently no approved treatment that specifically targets ApoE4-related risk. An abnormal result, in someone not well-suited to sitting with uncertain risk information, can produce lasting fear with no clear clinical benefit to offset it. This is not a test to order reflexively. It is a decision to make deliberately, in the context of a relationship with a physician who knows you well.

The Factors That Matter More Than Most People Realize

Even for patients who carry genetic risk, predisposition is not destiny. The most powerful levers we have for protecting the aging brain are modifiable, and several of them are far less intuitive than people expect.

Hearing Loss

If there is one finding from the recent dementia literature that consistently surprises people, it is the strength of the connection between hearing loss and cognitive decline. A 2025 meta-analysis found that moderate hearing loss increases dementia risk by 29%, and severe hearing loss by 49%, based on objective audiometry data. A separate 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, demonstrated that treating hearing loss reduced cognitive decline in high-risk older adults.

The mechanism involves two compounding problems. First, a deteriorating auditory system forces the brain to work harder simply to decode speech, diverting cognitive resources from other functions over time. Second, the social withdrawal that often accompanies untreated hearing loss is itself an independent dementia risk factor.

In our patient population, resistance to hearing aids is almost always social rather than practical. Hearing aids feel like an admission of aging. This perception needs updating. Modern devices are small, discreet, technologically sophisticated, and in many cases nearly invisible. The trade-off being made by avoiding them is not cosmetic comfort. It is cognitive health. If you have noticed any difficulty following conversations, particularly in noisy environments, an audiology evaluation should be a priority.

Vision Loss

The 2024 Lancet Commission update added untreated vision loss as a newly recognized modifiable risk factor, supported by two large meta-analyses. The mechanism parallels hearing loss closely: sensory deprivation increases cognitive load and accelerates social withdrawal. Conditions such as cataracts and macular degeneration that are correctable or manageable deserve prompt attention, not only for quality of life but for what we now understand about their relationship to brain health.

Social and Intellectual Engagement

Among the executives, entrepreneurs, and professionals we work with across the Bay Area, retirement represents a particular and underappreciated risk. A demanding career provides cognitive stimulation, social connection, and purposeful engagement by default. When it ends, those inputs can disappear abruptly in ways that feel liberating at first and become quietly harmful over time.

Social isolation is on the Lancet Commission list for good reason. Sustained social and intellectual engagement builds cognitive reserve, the brain's capacity to withstand the structural changes of aging without functional decline. The research does not point to any single protective activity. What matters is maintaining complexity: learning new skills, sustaining meaningful relationships, pursuing work or interests that require genuine mental effort. For patients in or approaching retirement, we treat this as a clinical priority, not a lifestyle suggestion.

Vascular Health

The relationship between cardiovascular and cerebrovascular health is direct and well established. What damages the heart's blood supply tends to damage the brain's as well. Hypertension has long been on the Lancet Commission list; the 2024 update added high LDL cholesterol, drawing on evidence from cohort studies involving over one million participants. Sustained elevation of either accelerates damage to the small vessels that supply the brain, contributing to vascular dementia and likely compounding Alzheimer's pathology.

In a proactive concierge medicine model, vascular risk management is not something we wait for symptoms to prompt. It is an ongoing priority, measured, tracked, and adjusted over time, beginning well before the ages at which most conventional practices begin to worry about it.

Sleep

Sleep is not yet on the Lancet Commission's formal list, but the evidence connecting sleep quality to dementia risk is growing rapidly enough that we treat it as a clinical priority. The brain's glymphatic system, which clears metabolic waste including amyloid beta during deep sleep, is impaired by both chronic sleep deprivation and untreated obstructive sleep apnea. Sleep apnea is common, frequently undiagnosed in high-functioning individuals whose daytime performance masks the condition, and highly treatable. Snoring, unrefreshed sleep, or daytime fatigue despite adequate hours in bed are all reasons to pursue a formal sleep evaluation.

Depression

Depression and dementia share a complex and bidirectional relationship. Depression is both a risk factor for cognitive decline and, in some cases, an early symptom of it. What is consistently clear is that untreated depression is harmful to brain health. Among high-performing patients, depressive symptoms are frequently minimized or dismissed, often because professional output remains intact long after wellbeing has quietly declined. This is a pattern worth being alert to, both personally and in the people around you.

Physical Activity

Exercise addresses more dementia risk factors simultaneously than any other single intervention. It increases cerebral blood flow, promotes neurogenesis, reduces systemic inflammation, and improves sleep quality. Both resistance training and aerobic exercise contribute meaningfully and independently. A complete fitness approach that includes both, along with balance, mobility, and power development, is the most evidence-supported investment a person can make in their long-term cognitive health.

What This Means in Practice

Cognitive longevity is not the result of a single intervention or a single test. It is the accumulated outcome of decisions made across decades, about how we manage our vascular health, how we sleep, how we move, how we engage socially and intellectually, and how promptly we address the sensory changes that most people quietly accept as inevitable.

Genetics matters. ApoE4 status is real information, worth knowing in the right context and for the right patient. But it is context, not conclusion. The patients we see thriving cognitively into their seventies and beyond are not necessarily the ones with the most favorable genes. They are the ones who treated brain health as a priority long before it became urgent.

That is the approach we take at Crescendo MD, and it is one of the most important conversations we have.

Crescendo MD is a concierge medicine practice based in Portola Valley, serving high-performing individuals and families across the San Francisco Bay Area. Our approach combines rigorous evidence-based medicine with personalized, proactive care focused on longevity, performance, and long-term health. To learn more or inquire about membership, visit https://www.crescendomd.com/inquire