What is early-onset Alzheimer’s disease, and who is at risk? Here’s what you should know about the condition that affects about 200,000 people in the United States.

It’s not just for old people.

Alzheimer’s disease is usually thought of as something senior citizens get. While that is often true, it’s not always the case: Up to 5% of people diagnosed with Alzheimer’s are under age 65—usually in their 40s or 50s—and are considered to have an “early onset” or “younger onset” of the disease.

The symptoms are the same, but may be hard to recognize.

Symptoms of early-onset Alzheimer’s are no different than symptoms of more traditional cases, says Mary Sano, Ph.D., professor of psychiatry and director of Alzheimer’s disease research at Mount Sinai School of Medicine in the Bronx. But because the condition is so rare in adults under 65, the signs may not be recognized as quickly by patients themselves, or by those around them.

“By the time people ask for help, something strange has probably been going on for at least six months,” says Sano. “And often, it’s family members and close friends who can provide a point of view that a change has occurred, which can allow that person to realize something is wrong.”

Younger people may need extra testing.

Because early-onset Alzheimer’s disease is so uncommon, diagnosis may also require testing above and beyond what a senior citizen might undergo. “We want to demonstrate that what’s really present is a cognitive problem and not a psychological or physical problem,” says Sano. “For a younger person, we’ll do a more rigorous workup, including imaging and other tests, because we want to make sure we get this right.”

Early-onset disease has a strong genetic component, so family history—if the patient knows enough about it—can be a big part of a person’s diagnosis, as well. A blood test can determine whether someone has a gene mutation that puts them at higher risk for familial Alzheimer’s, but cannot prove whether they have (or will get) the disease.

Keep in mind, it’s not common.

First things first: Early-onset Alzheimer’s disease is uncommon, and it’s not responsible for most cases of middle-aged forgetfulness—like not being able to remember where you put your keys, or the name of someone you met at a cocktail party last night, for example.

Episodes like these, says Sano, are most likely due to preoccupation or periods of temporary stress, and usually aren’t anything to worry about.

But you should know the warning signs.

When you should be concerned, she says, is when problems with your memory begin to interfere with your ability to do the things that are most important to you, or when you start to have difficulty completing common, everyday tasks. “It’s the persistence and the erratic nature of the symptoms that’s the real warning sign.”

In fact, Sano says, people with early-stage Alzheimer’s disease often subconsciously modify or adapt their routines to the point where they don’t even notice specific red-flag incidents. According to the Alzheimer’s Association, warning signs may include the regular use of memory devices, relying on friends and family to do things you used to handle yourself, or withdrawal from work or social activities.

Symptoms are different for everyone, but one thing to watch for is difficulty remembering and retaining new information, says Sano. “Not being able to learn your new computer password, or to learn a new activity or take on a new project—those are usually the challenges at the earliest stages of the disease,” she says.

As the disease progresses, however, all forms of memory are affected. Early-onset Alzheimer’s can be especially devastating because people in their 40s and 50s are often still working and caring for children. “They’re at risk for having more functional loss, and having their life and their family’s lives affected much more than someone who’s several decades older,” says Sano. “And so the management of the disease really requires a lot of thoughtfulness and a lot of extra service.”

This is how it’s treated.

There is no cure for Alzheimer’s disease, no matter what age onset occurs. But there are drugs that can slow its progression, and there are ways in which Alzheimer’s patients and their families can better manage living with the disease.

Staying physically, socially and mentally active can also provide protection against the disease and may help people with early-stage Alzheimer’s disease maintain their cognition longer, says Sano. Specifically, research has shown that doing crossword puzzles and speaking a second language may help slow declines in thinking and memory.

In addition, there are many opportunities for Alzheimer’s patients to take part in ongoing research, says Sano, which may lead the way to better treatment options. She recommends talking to your doctor or visiting the National Institutes of Health’s Alzheimer’s Disease Education and Referral Center online for information about clinical trials happening near you.

The causes of Alzheimer's disease are unknown, but the condition does have theorized causes, like acetylcholine deficiency and risk factors related to its development. Alzheimer's disease is a progressive neurological (brain) disease that leads to the loss of cognitive functions such as memory, thinking, and reasoning.¹

Complex brain changes can begin years or even decades before you experience any symptoms. Researchers believe genetics combined with lifestyle and environmental factors leads to the development of this condition.²³ Here's what you need to know.

Theories

Alzheimer’s disease results in a significant loss of brain cells called neurons and their connections, known as synapses. This loss starts in the areas of the brain that control memory.

As damage spreads throughout the brain, more cognitive and physical abilities are affected, causing the brain to shrink physically. There are two main hypotheses for the development of Alzheimer’s: cholinergic and amyloid.⁴

Cholinergic Hypothesis

The cholinergic hypothesis is the earliest explanation of Alzheimer's disease. Cholinergic neurons throughout the brain play an essential role in cognition, including learning and understanding. People with Alzheimer's disease show a severe loss of cholinergic neurons.⁵

Another theorized cause of Alzheimer's disease is a deficiency in the brain messenger chemical called acetylcholine (ACh). ACh plays a role in brain functions like learning and memory.⁵

The only approved medications for Alzheimer's help maintain the level of ACh in the brain. These drugs can temporarily slow down cognitive symptoms, but they don't prevent long-term brain damage.⁵

Amyloid Hypothesis

For many years, researchers believed that abnormally high levels of beta-amyloid—a protein that surrounds nerve cells—formed amyloid plaques in the brain. These plaques are thought to contribute to the cognitive loss associated with Alzheimer's disease. The beta-amyloid hypothesis was based on an influential 2006 research paper.⁶

Treatment endeavors using medications to target beta-amyloid did not result in improved symptoms of Alzheimer's disease. In addition, researchers found that amyloid plaques can also be found in people without Alzheimer's disease as they age.⁷

One report cast doubt on this hypothesis. One neuroscientist found that the images in the 2006 study were altered. Since then, researchers have approached the beta-amyloid hypothesis with caution.⁸

Results from the clinical trial of a medication called Leqembi (lecanemab) showed some renewed support for the role of beta-amyloid in Alzheimer's disease development. Lecanemab reduced the amount of amyloid in participants' brains, resulting in a moderate improvement of symptoms after 18 months.⁹

More research and trials are necessary to confirm the debated hypothesis. Investigators are also looking into new explanations for neuron loss as well. 

Is Alzheimer’s Disease Hereditary?

Some cases of early-onset Alzheimer’s disease are familial, meaning children may inherit certain mutations from their parents. In those cases, gene mutations cause the disease. Consider speaking to a healthcare provider about genetic testing if you have a history of early-onset Alzheimer’s disease in your family.

About 70% of Alzheimer’s disease cases are related to genetic factors.¹⁰ The genetics of late-onset Alzheimer’s disease is less clear: It doesn’t seem to run in families. 

The gene that can most affect your risk of late-onset Alzheimer’s is apolipoprotein E (APOE). Everyone has some form (or variant) of APOE in their DNA. You’re more likely to develop the disease if you inherit the ɛ4 variant. On the other hand, having the relatively rare APOE ε2 variant can actually help protect you from Alzheimer’s disease.⁷¹¹¹²

Who Gets Alzheimer’s Disease?

Some people are more likely to develop Alzheimer's than others. Factors that can contribute to risk include:¹²

• Age: This is the most important risk factor; most Alzheimer's symptoms start after age 65, and the percentage of people who have Alzheimer's increases with age. Forty percent of people over the age of 85 have Alzheimer's.¹³
• Biological sex and gender: Nearly two-thirds of Alzheimer's cases are in people assigned female at birth. However, women may not be at an increased risk of Alzheimer's. For example, the difference may appear because women live longer than men on average; in the United States, the rates of women and men who develop Alzheimer's at each age are the same. Other studies have also revealed sex and gender bias in older research.⁷
• Ethnicity: Alzheimer's disease is common in Black and Hispanic populations. However, when researchers consider socioeconomic factors and health conditions, the differences in risk go away.¹⁴

Risk Factors

Researchers have identified different conditions, injuries, and other circumstances that can also contribute to the development of Alzheimer’s disease.¹¹

Vascular (Blood Vessel) Conditions

These conditions include high blood pressure (hypertension), heart disease, and stroke. Issues with blood vessels (for example, because of heart failure) can affect the blood supply to the brain, which can lead to brain inflammation and eventually Alzheimer’s disease.⁷

Metabolic Conditions

These include type 2 diabetes, high LDL cholesterol, and obesity. In particular, experiencing high LDL cholesterol levels and obesity during your midlife can increase your Alzheimer’s risk.¹⁵

Depression

Depression can raise your risk of Alzheimer’s. Antidepressant treatment may reduce this risk, but there aren’t enough studies to say for sure. Depression can also be an early sign of Alzheimer’s, as dementia can cause similar mood symptoms.¹³¹⁶

Social Isolation and Loneliness

Social isolation means lacking social interaction. Loneliness is different—it’s feeling alone or separated, which can happen even when you’re around other people. Both are risk factors for Alzheimer’s disease. 

Getting back into social activities can help protect you. Talking to others or volunteering can improve your mood, cognition, and overall well-being.¹⁷

Traumatic Brain Injury (TBI)

Traumatic brain injury happens when you experience a blow or jolt to the head. A history of TBIs can increase the risk of Alzheimer’s disease. This is especially true for severe injuries, but even mild TBI (like a concussion) can have a long-term impact.³¹⁸

Heavy Alcohol Use

Heavy alcohol use is associated with changes in the brain and cognitive decline, though there’s not enough evidence to say that it causes these issues. This doesn’t mean you have to quit alcohol entirely—light to moderate drinking in middle to late adulthood has been shown to decrease the risk of cognitive decline and dementia.¹⁹

Smoking

People who've never smoked or have quit smoking long-term may have a lower risk of developing Alzheimer's disease. Decreasing the habit can still reduce your risk if you don't stop smoking completely. 

Secondhand smoke can also increase your chance of developing Alzheimer's—especially if you're exposed at home.²⁰¹⁵

Hearing Loss

Alzheimer’s disease is associated with hearing loss. Researchers don’t know why or if one condition causes the other.

A major hypothesis is that hearing impairment may lead to social isolation, which is a risk factor for Alzheimer’s disease. Another hypothesis is that people with hearing loss require more cognitive resources to process sounds, which leaves fewer resources for other cognitive functions.²¹

Air Pollution

Higher levels of tiny particulate matter (PM 2.5), which is pollution from sources like power plants, construction sites, and fires, are associated with higher rates of Alzheimer's disease. 

Other types of pollution, such as nitrogen oxides (emitted from burning fuel in cars and power plants) and sulfur dioxide (emitted from burning fossil fuels at industrial facilities), can also cause brain damage similar to that seen in people with Alzheimer’s disease.²²⁷

Physical Inactivity

Being active reduces your risk of Alzheimer’s disease and all other causes of dementia. One review considered studies that followed participants for at least 20 years and found that physical activity could help protect against Alzheimer’s disease in the long term.²³

Low Mental Engagement

Just like physical activity is important, staying mentally active—especially before age 20—can help protect you from Alzheimer’s disease. Studies have shown that higher education can reduce your risk of dementia, as can other cognitively stimulating activities like reading, speaking a second language, and playing music. Having a mentally challenging job can also help.³

A Quick Review

Alzheimer’s disease results in the loss of cognitive functions like memory and thinking, typically in people aged 65 or older. Researchers don’t yet know how Alzheimer’s disease develops, though it’s likely because of a combination of genetic and environmental factors. 

Age is the biggest risk factor for Alzheimer’s disease, and other known risks include heart disease, brain injury, and low mental or physical activity. Studies are beginning to include demographically diverse populations to better understand who gets Alzheimer’s disease, but there’s no way to predict exactly who will develop it at this time.

SOURCES

1. National Institute on Aging. What is Alzheimer's disease?
2. National Institute on Aging. Alzheimer's disease fact sheet.
3. Livingston G, Huntley J, Sommerlad A, et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. 2020;396(10248):413-446. doi:10.1016/S0140-6736(20)30367-6
4. National Institute on Aging. What happens to the brain in Alzheimer's disease?
5. Chen ZR, Huang JB, Yang SL, Hong FF. Role of cholinergic signaling in Alzheimer's disease. Molecules. 2022;27(6):1816. doi:10.3390/molecules27061816
6. Lesné S, Koh M, Kotilinek L, et al. A specific amyloid-β protein assembly in the brain impairs memory. Nature. 2006;440:352–357. doi:10.1038/nature04533
7. Breijyeh Z, Karaman R. Comprehensive review on Alzheimer's disease: Causes and treatment. Molecules. 2020;25(24):5789. doi:10.3390/molecules25245789
8. Science. Blots on a field?
9. van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in early Alzheimer's disease. N Engl J Med. 2023;388:9-21. doi:10.1056/NEJMoa2212948
10. Holstege H, Hulsman M, Charbonnier C, et al. Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer’s disease. Nat Genet. 2022;54(12):1786-1794. doi:10.1038/s41588-022-01208-7
11. National Institute on Aging. What causes Alzheimer's disease?
12. Alzheimer’s Association. 2022 Alzheimer's disease facts and figures. Alzheimer’s Dement. 2022;18(4):700-789. doi:10.1002/alz.12638
13. Kumar A, Sidhu J, Goyal A, et al. Alzheimer Disease. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022.
14. Woldemariam SR, Tang AS, Oskotsky TT, Yaffe K, Sirota M. Similarities and differences in Alzheimer’s dementia comorbidities in racialized populations identified from electronic medical records. Commun Med. 2023;3(1):50. doi:10.1038/s43856-023-00280-2
15. Keene CD, Montine TJ, Kuller LH. Epidemiology, pathology, and pathogenesis of Alzheimer disease. In: Post TW. UpToDate. UpToDate; 2022.
16. National Institute on Aging. Depression and older adults.
17. National Institute on Aging. Loneliness and social isolation - tips for staying connected.
18. Barnes DE, Byers AL, Gardner RC, Seal KH, Boscardin WJ, Yaffe K. Association of mild traumatic brain injury with and without loss of consciousness with dementia in US military veterans. JAMA Neurol. 2018;75(9):1055–1061. doi:10.1001/jamaneurol.2018.0815
19. Rehm J, Hasan OSM, Black SE, et al. Alcohol use and dementia: A systematic scoping review. Alz Res Therapy. 2019;11(1) doi:10.1186/s13195-018-0453-0
20. Choi D, Choi S, Park SM. Effect of smoking cessation on the risk of dementia: A longitudinal study. Ann Clin Transl Neurol. 2018;5(10):1192-1199. doi:10.1002/acn3.633
21. Ralli M, Gilardi A, Stadio AD, et al. Hearing loss and Alzheimer's disease: A review. The International Tinnitus Journal. 2019;23(2):79-85. doi:10.5935/0946-5448.20190014
22. Power MC, Adar SD, Yanosky JD, Weuve J. Exposure to air pollution as a potential contributor to cognitive function, cognitive decline, brain imaging, and dementia: A systematic review of epidemiologic research. Neurotoxicology. 2016;56:235-253. doi:10.1016/j.neuro.2016.06.004
23. Iso-Markku P, Kujala UM, Knittle K, Polet J, Vuoksimaa E, Waller K. Physical activity as a protective factor for dementia and Alzheimer's disease: Systematic review, meta-analysis and quality assessment of cohort and case-control studies. Br J Sports Med. 2022;56(12):701-709. doi:10.1136/bjsports-2021-104981

Almost 7 million people in the United States live with Alzheimer’s disease, but the burden of that diagnosis is not carried equally among the racial groups that make up this country.¹ Black people carry the highest risk of developing dementia, followed by Indigenous Americans, and people of Hispanic and Latino descent.² Despite this increased risk, these groups are often underrepresented in research and clinical trials and are more likely to face barriers to accessing quality care and basic resources like healthy foods and clean air.  

The underlying risk factors of dementia—hypertension, diabetes, air pollution, poor nutrition, and lack of physical activity—all have a connection to the inequalities experienced by communities of color and people with lower incomes. As our country becomes more diverse, we need to build a more equitable system that allows for better health outcomes for communities. 

Dementia and Alzheimer’s disease are conditions that typically manifest as we grow old, but prevention starts with the resources we have early on in our lives. Something as simple as proximity to fresh air and clean food could improve your health outcomes and the health of future generations.

Why Some People Don’t Seek a Dementia Diagnosis Sooner

Communities of color, despite having higher risks of dementia, tend to seek care from a provider much later than white communities.³ But why?

Evidence suggests that racial bias has led to stark healthcare inequalities for people of color. Some examples in the research show that healthcare providers are more likely to ignore symptoms in people of color, and Black and Latino people are less likely to receive appropriate and advanced treatment options for health conditions.⁴

When it comes to getting a dementia diagnosis, research found it can take four months longer, on average, for Black people to receive a diagnosis, and over a year longer for Hispanic people. When people from these communities finally get a diagnosis, they’re more likely to have significant cognitive and functional difficulties as a result of this diagnostic delay.³ For the best outcomes, it’s important to address dementia symptoms as soon as they appear. 

Implicit bias is a term for negative and unconscious beliefs and attitudes about certain racial identities, genders, sexual orientations, and other identifying factors. These biases can influence you to make judgments about or discriminate against certain groups of people.⁵⁴

Barriers to Dementia Care and How to Bridge the Gap

Dementia is a leading cause of death in Black Americans and continues to be a significant risk factor for Latino, Indigenous, and Asian communities in the United States.⁶⁷³

Current statistics show that approximately 40% of primary care providers—who are considered frontline resources in dementia care—come from diverse racial and ethnic backgrounds. Because communities of color often experience racial discrimination in healthcare systems, they prefer working with providers who understand their cultural background or speak their language.⁸

Additionally, drug trials that test new medical treatments have excluded people of color due to discriminatory practices in research. 

The High Cost of Treatment

Caring for a loved one with dementia can be financially challenging. A 2022 study found that the lifetime cost of care for a person with Alzheimer’s disease can be over $400,000. This cost is especially difficult for uninsured families and those who live in areas with limited resources.¹⁰

In addition, people of color are more likely to be uninsured than their white counterparts. 2021 U.S. Census Bureau data outlined the differences in healthcare coverage by race. They found that 18.8% of AIAN communities, 17.7% of Latinos, 10.1% of Pacific Islanders, and 9.6% of Black people are uninsured—as compared to 5.7% of white people.¹¹

The cost of dementia treatment through Medicaid is expected to continue to grow exponentially by 2050. As the prevalence of the disease increases, affordable healthcare programs will be necessary to care for a growing population of people with dementia.¹²

Given the cost of caring for someone with dementia, many people cannot afford outside help and in turn care for their loved ones themselves.

Frequently Asked Questions

Can dementia be cured?

There is currently no cure for dementia, but having access to treatment can help slow disease progression.¹³

Is Alzheimer's disease hereditary?

While you don’t need to have a family history of Alzheimer’s disease for you to get Alzheimer’s, some research suggests that those with a first-degree relative with Alzheimer’s are more likely to develop the disease, and the risk increases with each affected relative.

Your direct environment plays a significant role in your Alzheimer’s risk.¹⁴¹⁵

How can I prevent dementia?

While there aren’t any proven ways to prevent dementia, you can reduce your risk by lowering your chances of developing diseases that are linked to dementia, like high blood pressure and heart disease.

Methods for managing your risk include eating a heart-healthy diet, exercising regularly, getting enough sleep, not smoking, and limiting alcohol consumption.¹⁶

SOURCES

1. Alzheimer’s Association. Alzheimer’s disease facts and figures.
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3. Lin PJ, Daly AT, Olchanski N, et al. Dementia diagnosis disparities by race and ethnicity. Med Care. 2021;59(8):679-686. doi:10.1097/MLR.0000000000001577
4. Sabin JA. Tackling implicit bias in health care. N Engl J Med. 2022;387(2):105-107. doi:10.1056/NEJMp2201180
5. American Psychological Association. Implicit bias.
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8. Centers for Disease Control and Prevention. Barriers to equity in Alzheimer’s and dementia care.
9. Reardon S. Alzheimer's drug trials plagued by lack of racial diversity. Nature. 2023;620(7973):256-257. doi:10.1038/d41586-023-02464-1
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11. U.S. Census Bureau. Health Insurance Coverage by Race and Hispanic Origin: 2021.
12. Alzheimer's Association. Costs of Alzheimer’s to Medicare and Medicaid.
13. Alzheimer's Association. Treatments for Alzheimer's.
14. Adkins-Jackson PB, George KM, Besser LM, et al. The structural and social determinants of Alzheimer's disease related dementias. Alzheimers Dement. 2023;19(7):3171-3185. doi:10.1002/alz.13027
15. Alzheimer's Association. Is Alzheimer's genetic?.
16. National Institute on Aging. Can I prevent dementia?.