Alzheimer’s disease is a form of dementia. Doctors use the term “dementia” to describe symptoms that affect brain function, including memory and thinking.

The causes of Alzheimer’s disease remain unclear. However, as research continues, treatments are available to help manage some symptoms of Alzheimer’s disease and slow its progression.

This article lists and explains 10 facts about Alzheimer’s disease.

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According to the Alzheimer’s Association, Alzheimer’s disease accounts for 60–80% of dementia diagnoses in the United States. Most people with Alzheimer’s disease also show brain changes linked to other types of dementia.

In 2019, researchers estimated that 5 million people in the United States were living with Alzheimer’s disease and that the number would increase to 13.9 million by 2060.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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According to the Alzheimer’s Association, around two-thirds of people who receive an Alzheimer’s disease diagnosis are females.

The Alzheimer’s Association also notes that researchers previously linked this increased risk to the statistical likelihood of females living longer than males. Because age is a risk factor for Alzheimer’s disease, they thought that females’ longer life spans drove the figures around their increased dementia risk.

However, more research is coming to light that highlights sex-specific causes of this increased Alzheimer’s disease risk in females. For example:

  • One 2019 study found links between a female’s age at first menstrual cycle, their age of menopause, and their risk of developing Alzheimer’s disease.
  • Some research has connected the biology of the female brain to increased production of an Alzheimer’s disease-linked protein called tau.
  • Increased participation in the workforce and greater levels of education for females over the last 100 years may have resulted in lower rates of Alzheimer’s disease. This could explain why older females who make up today’s data might experience Alzheimer’s disease more often than males, and this may change over time.

According to a 2021 review, several studies have linked Alzheimer’s disease to cardiovascular disease (CVD).

The researchers suggest that the two diseases share many risk factors, including:

Some researchers have also linked inflammation and the actions of bacteria in the gut to the development of both CVD and Alzheimer’s disease.

Because researchers are still establishing the precise cause of Alzheimer’s disease, more studies are necessary.

The Centers for Disease Control and Prevention (CDC) ranks Alzheimer’s disease seventh among leading causes of death in the United States. According to CDC data from 2021, 119,399 people died as a result of Alzheimer’s that year.

However, among people ages 65 years and older, Alzheimer’s disease is the fifth leading cause of death, according to the Alzheimer’s Association. While deaths due to stroke, heart disease, and HIV decreased in the time period from 2000 to 2019, deaths due to Alzheimer’s disease increased by 145%.

The Alzheimer’s Association links this increase to the COVID-19 pandemic of 2020 and 2021.

A higher level of education may improve a person’s cognitive reserve — the brain’s ability to account for damage in its processing. The Alzheimer’s Association suggests that more cognitive reserve may help reduce the impact of Alzheimer’s disease-linked brain damage on cognitive function.

A 2020 review of 65 studies from 24 countries on the effects of education found that every additional year of education reduced a person’s Alzheimer’s disease risk by 8%. And the results of a 2023 study involving 318,535 participants suggest that a person’s level of education could cancel out a genetic risk of Alzheimer’s disease.

Older adults have a higher risk of Alzheimer’s disease than others, and the risk increases each year.

According to the United Kingdom’s National Health Service (NHS), 1 in 14 people over 65 years of age get Alzheimer’s disease, while 1 in 6 people over 80 years of age do.

Alzheimer’s disease is complex, and age is not the only factor. For example, 1 in 20 people with Alzheimer’s disease are under 65 years of age — a subtype known as early onset Alzheimer’s disease.

A researcher named Alois Alzheimer gave Alzheimer’s disease its name in 1906.

While working at a psychiatric clinic, he identified the disease in a woman known as Auguste D. She experienced memory loss, confusion, and hallucination up until death. During the autopsy, Alzheimer identified anomalies while examining her brain — namely, plaques and tangles of nerves.

Doctors use similar methods to identify the disease today.

Anosmia — the loss of ability to smell — might be an important early sign of Alzheimer’s development, according to a 2022 study.

The researchers found that lower results on a test for sense of smell, known as olfactory scores, indicated higher levels of Alzheimer’s disease-related brain damage and dysfunction. Every lost olfactory score point had links to a 22% increase in Alzheimer’s disease risk.

Brain scans also found that those reporting greater anosmia over time had greater buildup of Alzheimer’s disease-linked proteins, such as amyloid and tau. These appeared in brain regions related to both sense of smell and memory.

Alzheimer’s disease is responsible for a huge healthcare cost burden across the United States.

Estimates of the total of medical payments related to healthcare and hospice care for dementia in 2023 are as high as $345 billion, according to the Alzheimer’s Association. While this figure also accounts for other types of dementia, most people with dementia have Alzheimer’s.

On top of this, around 11 million family members and unpaid caregivers provided around 18 billion hours of Alzheimer’s disease care in 2022, which the Alzheimer’s Association valued at around $339.5 billion. The total Medicaid payments for those ages 65 and over with Alzheimer’s disease were around three times as much as for those without the condition.

Alzheimer’s disease gets worse over time. On average, the Alzheimer’s Association estimates that people with the disease live for 4–8 years after diagnosis. However, life expectancy with Alzheimer’s depends on a variety of factors. Some people live for 20 years after receiving an Alzheimer’s diagnosis.

Alzheimer’s and dementia resources

To discover more evidence-based information and resources for Alzheimer’s and dementia, visit our dedicated hub.

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Alzheimer’s disease is the most common type of dementia. The risk of Alzheimer’s disease has links to female sex, advanced age, and cardiovascular disease, although the underlying cause is not clear. It is a costly, progressive disease that has varying effects on life expectancy.

Since its first diagnosis in 1906, Alzheimer’s disease has become a leading cause of death in the United States. Several factors may have links to Alzheimer’s disease development, including a lower level of education.

Common symptoms include memory loss and difficulties with cognition. Less well-known symptoms, such as a reduced sense of smell, are also possible.