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What's the Difference Between Dementia and Alzheimer's?

Last updated: March 2022

Dementia and Alzheimer’s are different conditions. Dementia is an umbrella term that includes a number of conditions that result in cognitive impairment. Dementia refers to an array of symptoms that impact memory, activities of daily living, and the ability to communicate. Alzheimer’s disease is the most common form of dementia. It is a progressive condition that gets worse over time, affecting thinking, memory, and language.1

The terms Alzheimer’s and dementia have been around for 100 years and are often incorrectly used interchangeably.2,3 However, they are not the same, and the differences can create confusion for patients, families, and caregivers.3 It is important to get an accurate diagnosis in order to receive the best available treatment.

Definition of dementia

The National Institute on Aging (NIA), defines dementia as a brain disorder that affects communication and performance of daily activities. Dementia is not a disease. It is a clinical presentation of symptoms. Alzheimer’s is a disease that is a form of dementia that affects the parts of the brain that control thought, memory, and language.3

Symptoms that are part of dementia affect memory, thinking, and social abilities. They are considered severe as they interfere with independent daily functioning.4 With dementia, doctors know that something is wrong with the brain, but don’t have specific information about what is causing difficulties with memory or cognition.

Dementia is most often an irreversible decline in mental function.2 A catchall phrase, it encompasses multiple disorders that can cause chronic memory loss, personality changes, and impaired reasoning, according to Dr. Dan Blazer from Duke University Medical Center. Alzheimer’s disease is just one of those. To be considered dementia, the disorder must be severe enough to interfere with daily life, says Dr. Lyketsos, director of the Johns Hopkins Memory and Alzheimer’s Treatment Center in Baltimore.2

To note, some causes of dementia are reversible, such as certain thyroid conditions or vitamin deficiencies.1

Diagnosing dementia

Dementia can be diagnosed when at least two areas of cognitive decline are confirmed. They produce noticeable change compared to functioning earlier in life. They interfere with social, professional and occupational areas of normal daily living. These can include:2,3

  • Changes in thinking and spatial skills
  • Memory decline and loss
  • Poor judgment, planning, and reasoning skills
  • Disorganization, decreased focus, and lack of attention
  • Changes in language and communication skills

Definition of Alzheimer’s

Alzheimer’s is a specific disease that is a kind of dementia that affects the parts of the brain that control thought, memory, and language.3 As defined above, dementia presents as a group of symptoms, while Alzheimer's disease is the most talked about and most common cause of dementia.4

Alzheimer’s affects memory, cognition, and behavior. There is currently no cure for this progressive and irreversible disease that destroys a person’s memory and thinking skills.2 Alzheimer’s destroys one’s ability to live independently and carry out basic tasks.

There is biological evidence that amyloid plaques and tangles build up in the brain in people with Alzheimer's. The plaques and tangles can be seen microscopically, and just recently, they can also be seen through images on a PET scan that uses tracers that bind to the proteins. They can also be found in cerebral spinal fluid, but this diagnostic technique isn’t commonly used in the U.S.2

The Centers for Disease Control (CDC) reports Alzheimer’s disease is the most common cause of dementia, accounting for 50 to 70% of all cases of dementia. Symptoms of Alzheimer’s include impaired thinking, loss of speech and language comprehension, and confusion.3

Diagnosing Alzheimer’s

There are no tests to diagnose Alzheimer’s. Neurologists rely on a thorough medical history, patient and family reporting of symptoms, as well as observation that rules out other conditions.

Alzheimer's disease can’t be diagnosed with complete accuracy while someone is alive. Alzheimer's can only be diagnosed after death, upon autopsy. A neuropathologist can identify hallmark pathological features of brain tissues that are present if a person had Alzheimer's disease.

A new PET scan technology is reported to have 95% diagnostic accuracy, but until now it has been used only as a way to evaluate Alzheimer’s in people with atypical symptoms.

The difference between dementia and Alzheimer's

People diagnosed with dementia have a set of symptoms evaluated by a neurologist. Through the use of screenings, blood tests, mental status exams, and brain scans, doctors can identify the presence of those symptoms.

Increased access to educational information and more public awareness is needed to enhance understanding of the difference between dementia and Alzheimer’s. There are some forms of dementia, such as those caused by a drug interaction or vitamin deficiency, that are temporary or reversible. Alzheimer’s progression, however, can be delayed by medication but is not reversible.

In the future, if scientists can determine the cause of Alzheimer’s disease, it may lead to the discovery of improved treatments, and potentially a cure.3

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