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Alzheimer's Disease Overview

Older age remains the greatest known risk factor for Alzheimer’s disease, a type of dementia for which there’s no cure—only treatments to slow its progression. And while there’s no proven way to prevent this degenerative brain disease, adopting certain healthy lifestyle changes may lower one’s risk for cognitive decline.

Alzheimer's disease, the most common type of dementia, damages parts of the brain involved in memory, thinking, and judgment, among other cognitive skills. Almost half of people afflicted with Alzheimer's are ages 75 to 85 and older.

What Is It?

Alzheimer's is the most common cause of dementia, a group of conditions where there's a decline in cognitive capabilities affecting memory, judgment, and thinking. Dementia is not a normal part of aging. Still, the symptoms of Alzheimer's most often begin to appear around age 65, though the damage that occurs to brain cells occurs decades earlier before these signs emerge.

The disease is known as a progressive brain disorder, meaning that brain damage worsens with time, beginning as memory and learning impairment and eventually developing into an inability to care for one's self, communicate and engage with others, and walk and move around during late-stage Alzheimer's. On average, someone with the disease lives four to eight years following diagnosis. Alzheimer's is the fifth leading cause of death in folks 65 and older. While more than six million Americans have Alzheimer's, that figure is expected to more than double by 2050.


When Alzheimer's starts in one's 30s or 40s, this is considered "early onset." It is a rare form of the disease, and may be caused, in part, by a genetic mutation in the APOE gene.

More often, brain changes over the course of decades, leading to the emergence of the first symptoms of Alzheimer's. The disease is most commonly diagnosed in a person's mid-60s.

There are three known stages of Alzheimer's disease, depending on level of mental function impairment:

Mild disease. Friends and family may notice disruptions to everyday function as well as memory loss and confusion.

Moderate disease. Damage in the brain advances, further affecting brain regions involved in language and thinking. It's at this stage that people with the disease may forget familiar people and personality changes may appear.

Severe disease. As damage spreads throughout more of the brain, patients lose their ability to communicate, take care of themselves, and can no longer control certain body functions, like swallowing and toileting.


The disease is most often diagnosed in its mild stages. The following are some signs and symptoms of mild to moderate Alzheimer's disease:

Memory loss. Someone may notice that they have to keep copious notes to remember things (more so than has been normal for them) or they can't remember important dates. Repeating the same questions is another sign of early memory problems. Losing items frequently—and not being able to find them—may also occur.

Problems with word recall. Even familiar words become tough to remember. As Alzheimer's advances, this can look like problems reading, writing, and recognizing/understanding numbers.

Impaired reasoning and judgment. This may include struggles with problem solving or decision-making, such as shopping and cooking.

Inability to follow through with tasks. Things that could be done before, such as paying bills, becomes far more difficult than it used to be. It may take longer to complete tasks that require following step-by-step instructions.

Getting lost. Someone may have issues remembering how to get to familiar destinations, like the grocery store, post office, or a friend's home. They may leave in the car but not remember where they intended on going and, consequently, get lost. Wandering may also occur.

Trouble with balance. Experiencing vision and spatial issues may affect one's gait and balance.

Mood changes. These might include symptoms that mimic depression or anxiety. Their personality may also seem "off" or different. Appearing agitated, becoming overly worried, outbursts of foul language or impulsivity, or displaying anger may also appear.


Researchers don't yet know what causes Alzheimer's disease. However, it's clear that the development of plaques and tangles as well as changes in brain structure, such as brain shrinkage, are involved.

Genes. Having the APOE gene (apolipoprotein E) increases one's risk, especially for early-onset disease. There are likely other areas in the genome also associated with the development of Alzheimer's.

Family history. According to research, having one first-degree relative puts someone at about a 1.7-times greater risk of developing the disease. There's also increased odds if one has a second- or third-degree relative with Alzheimer's in the family.

Age. While Alzheimer's can occur in young or middle-age, 90% of cases are in older adults. Older age is the biggest risk factor for the disease.

Health. Chronic conditions such as heart disease, stroke, high blood pressure, diabetes, as well as obesity, may make someone more prone to developing Alzheimer's.

Lifestyle. An unhealthy diet, sedentary behavior, lack of sleep, and social isolation are all factors that may play a role in cognitive decline.


Not all memory problems or dementias are caused by Alzheimer's disease. Diagnosis is made with:

Medical history and exam. The challenge with possible dementia is that it may be difficult to ask the patient themselves about their symptoms. Doctors may also question loved ones about the patient's ability to perform everyday tasks, as well as concerning personality changes. Doctors will also review medications to make sure that something they're taking is not causing the confusion.

Cognitive tests. Assessments are given that measure memory, attention, judgment, thinking, and learning.

Medical tests. Because other conditions—from Parkinson's disease and other types of dementia to depression and even urinary tract infections—can produce symptoms that mimic Alzheimer's, physicians may order blood and urine tests, a neurological exam, and/or imaging scans (such as MRI or CT) to rule out other health problems.


There is no cure for Alzheimer's. Treatment focuses on managing symptoms and slowing down disease progression.

Medication. Certain drugs act on different brain chemicals. Medicines such as cholinesterase inhibitors can help improve memory, cognition, and behavioral symptoms. Other medications, like aducanumab, a new type of immunotherapy, can help reduce amyloid plaques to slow down the advancement of the disease. As Alzheimer's progresses, there are other drugs for more severe disease that can help patients retain daily functioning.

Other medications may be prescribed to help with specific symptoms, such as insomnia, depression, anxiety, and hallucinations and delusions.

Caretaking. Preserving one's quality of life is also important, and it can also help manage behavioral symptoms. This may include setting up one's home to be "Alzheimer's friendly," automating tasks of daily living (such as bill pay), preventing falls, and learning how to manage disruptions to routines, which can trigger behavior disturbances.


There is no guarantee that a person will avoid developing Alzheimer's in the future, especially since a combination of genetic, environmental, and lifestyle factors lead to its development. However, there are some risk factors that you can control.

A healthy heart. What's good for your heart is good for your brain. Maintain the health of blood vessels by regulating blood pressure and keeping cholesterol in check.

A brain-boosting diet. Diets such as the Mediterranean Diet and the MIND diet may help defray cognitive decline.

Regular exercise. Physical activity improves cerebral blood flow, decreases inflammation, triggers the production and release of growth factors in the brain and may decrease plaques.

Cognitive activities. Reading, playing games, crafting, and social interaction may help preserve brain function and keep the brain healthy.

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