Dementia and Alzheimer’s: Words and Terms to Know

A diagnosis of Alzheimer’s disease or dementia can be a frightening and bewildering moment. Along with the prospect of a long, difficult road ahead, you might be confronted with an overwhelming number of new words and phrases you’re unfamiliar with. 

It’s important to know medical terms and words for Alzheimer’s disease doctors will use in conversation. That includes a clear definition of dementia and Alzheimer’s disease. That’s where this glossary can be helpful. 

Here are some terms you might hear after a diagnosis of dementia or Alzheimer’s.

Alzheimer’s Disease and Dementia Terms


Activities of daily living: Sometimes called ADL, these are everyday tasks such as bathing, dressing, eating, grooming and using the toilet. These activities can become challenging for those with dementia.

Adult day services: Daily programs that allow individuals living with Alzheimer’s and dementia the opportunity to spend time with others, usually in a dedicated center or facility. These are not overnight facilities.

Advance directive: Legal document that clearly states what the person in question would want to occur in case of a medical emergency. These are also called living wills or power of attorney.

Adverse reaction: Negative side effect of a treatment or medication.

Alois Alzheimer: The researcher who, in 1906, first studied and described the memory loss disease that eventually received his name.

Alpha-synuclein: Protein that is abundant in the brain. It is the major constituent of Lewy bodies, which cause harmful chemical changes in the brain.

Alzheimer’s disease: The most common form of dementia, affecting between 60% and 70% of those with dementia, according to the World Health Organization. Alzheimer’s first affects the part of the brain associated with learning, so early symptoms often include changes in memory, reasoning and thinking.

>> Read “Detecting Alzheimer’s Symptoms & Stages

Apathy: People living with dementia or Alzheimer’s may lose motivation to participate in everyday activities. This may increase their reliance on caregivers.

Aphasia: General loss of ability to understand speech, or even to lose the ability to speak properly. This condition, somes called dysphasia, is separate from Alzheimer’s or other dementia.

ApoE: Gene that can exhibit different changes. One mutation is linked to a greater occurrence of Alzheimer’s, but it may not be the only gene involved in the disease.

Apraxia: The inability to perform tasks involving memory of patterns or sequences, such as tying shoelaces.

Assessment: An evaluation, usually by a doctor, of a person’s emotional, mental and social skills.

Assisted living facility: Senior community which provides accommodations, care and support for those that may need help with the everyday tasks of living, such as cleaning and cooking.

Atrophy: Atrophy of the brain occurs when it starts to weaken. Neurons and the connections between them can fail, which accelerates Alzheimer’s and dementia.

Autonomy: The ability of a person to make their own choices. Dementia patients quickly lose their autonomy, necessitating care.


Behavioral neurologist: A doctor whose specialty is behavioral and memory disorders that are caused by brain disease.

Beta-amyloid: Sometimes called amyloid-beta, this protein is a key factor in Alzheimer’s. It is formed when a larger protein called amyloid breaks down and collects in the brain, disrupting normal cell function.

Biomarker: Measures of what is happening inside the body as revealed by blood, imaging, urine and other tests are called biomarkers. In Alzheimer’s disease, MRI and PET scans are used most commonly as biomarkers, as well as are measures of proteins seen in brain scans and body fluids, such as blood and cerebrospinal fluid.


Caregiver: The main person in charge of caring for someone with a serious illness. In cases of dementia or Alzheimer’s, the caregiver many times is a spouse or adult child.

>> Read “The Complete Guide to Dementia for Caregivers

Cerebrospinal fluid: A fluid that protects and provides nutrition to the brain and spinal cord. Tests of the spinal fluid can detect proteins that are one of the causes of Alzheimer’s and dementia.

Clinical social worker: Social workers can help individuals and their families find resources or care services, such as adult day care, home care or skilled nursing services.

>> Read “50 Essential Dementia Resources

Cognitive abilities: Mental skills such as comprehension, judgment, learning, memory and reasoning are included in cognitive abilities. A decline in these skills may indicate dementia or Alzheimer’s disease.

Competence: The ability to make informed choices. This wanes in a person with Alzheimer’s or dementia.

Complementary therapies: Techniques used to aid in medical care apart from drugs, surgery and other methods. These sometimes are called alternative medicine.

CT or CAT scan: Computed tomography or computed axial tomography uses a combination of computer technology and X-rays to view tissue such as blood vessels, fat, organs and muscles.


Deficits: In terms of dementia and Alzheimer’s, deficits are mental and physical skills that a person has lost, has trouble with, or can no longer accomplish.

Delusion: A false idea that a person firmly believes and won’t stop believing even when presented with proof countering that belief. People with Alzheimer’s or dementia sometimes harbor delusions.

Dementia: The Alzheimer’s Association defines dementia as the general decline in mental ability that interferes with daily life. Dementia is a group of symptoms that cause decline of cognition, memory and reasoning. While Alzheimer’s disease accounts for the majority of all dementia cases, many different types of dementia exist.

>> Read “Understanding the Different Types of Dementia

Depression: Many people with cognition diseases experience depression, which is more severe than feeling down or sad. Depression can affect appetite and sleep and can hinder enjoyment of favorite activities. 

>> Read: “Depression in Seniors: What Can Be Done to Help?

Disorientation: Those with dementia often feel confused in space and time. Memory loss may contribute to this disorientation, causing difficulty in recognition of locations and people. Their sense of time may also be affected, causing changes in bedtime or meal time.

Durable power of attorney: Another term for advance directive, a legal document in which one can authorize another person to make legal decisions if they are no longer able to do so themselves.

Dysphasia: Sometimes called aphasia, it is the impairment of language skills, including speaking or understanding, often caused by stroke, trauma or the effects of dementia.


Early stage: The beginning stages of Alzheimer’s disease, with mild to moderate symptoms.

Early-onset Alzheimer’s disease: An occurrence of Alzheimer’s disease that starts before age 60, which is uncommon.

Electroencephalogram: Also called an EEG, this test measures brain activity.


Familial Alzheimer’s disease: Another uncommon form of Alzheimer’s, occurring earlier than age 65. It is caused by an inherited genetic mutation.

Frontotemporal disorders: Dementias caused by degeneration in the frontal and temporal lobes of the brain. 


Gait: A measure of how a person walks. In the later stages of Alzheimer’s, people often have a reduced gait, meaning it becomes harder to lift their feet as they walk.

Genetic counseling: A consultation with a trained genetic counselor to help explain whether you have a genetic likelihood of being affected by a condition such as dementia.

Genetic testing: Tests that may be conducted to measure your likelihood of contracting a disease. These may run from simple blood tests to more complicated procedures. These tests are often followed up by genetic counseling.

Geriatrician: Physician specializing in the medical care and treatment of seniors.

Guardian: A person who has been appointed by the courts to make authorized legal and financial decisions for someone who is otherwise incapable of doing so.


Hallucination: Feeling, hearing, seeing, smelling or tasting something that is not there. People with dementia or Alzheimer’s sometimes hallucinate.

Hippocampus: A complex structure deep in the brain’s temporal lobe. It has a major role in learning and memory. It is affected by a variety of neurological and psychiatric disorders.

Hoarding: Collecting and storing things to guard them. Some people with Alzheimer’s or dementia may hoard.

Hospice: Care, comfort and often pain management for a person as they approach the end of life. Hospice care can take place in special facilities or at home.


Incontinence: The loss of bladder or bowel control. This often occurs with people who have dementia or Alzheimer’s disease.


Lewy body dementia: Also called Parkinson’s dementia, Lewy body dementia is linked with abnormal deposits of a protein in the brain. These deposits, called Lewy bodies, change certain chemicals in the brain, causing problems with behavior, mood, movement and thinking.  

Living trust: A legal document in which someone can appoint someone else to invest and manage their assets. This is often recommended for someone who has been diagnosed with dementia or Alzheimer’s disease.

Living will: A legal document that outlines someone’s wishes about their medical care as they reach the end of life. For example, it may make clear whether a person wishes to be taken off life-support machines.

Long-term care: The suite of medical, personal and social services needed for individuals who are disabled or ill and face a long recovery, or who require a change in their living circumstances.

>> Read “How to Afford & Plan for Long-Term Senior Care


Magnetic resonance imaging: Most often called an MRI, this procedure uses magnets and radio waves to make pictures of organs and structures inside a body. It may be used to identify conditions in the brain that can cause or lead to Alzheimer’s disease or dementia.

Memory care: A type of care is provided for individuals living with Alzheimer’s, dementia or other memory loss. Usually provided in communities, this care is designed to provide security and comfort while addressing the needs of everyday living. 

>> Read “When Is the Right Time to Consider Memory Care?

Mild cognitive impairment: Slight, but noticeable, and measurable cognitive decline affecting decision-making or memory. 

Mini-Mental State Examination: A standard mental status exam that is used routinely to measure basic cognitive skills, such as short-term memory, long-term memory, language, orientation and writing.

Mixed dementia: A person with more than one type of dementia at the same time is said to have mixed dementia. For example, they may have the conditions that cause Alzheimer’s while also exhibiting dementia from a stroke or other brain injury.

MoCA: Another early assessment for diagnosing patients with illnesses from brain trauma to Parkinson’s. The assessment will also include appropriate follow-up and treatment plans.


Neurodegeneration: Progressive loss of the function or structure of neurons in the brain, which can even cause their demise. A number of neurodegenerative conditions, including Alzheimer’s disease, are caused by neurodegenerative processes.

Neurofibrillary tangles: Also referred to as just tangles, these are abnormal deposits of a protein, called tau, that collects inside the neurons of people with Alzheimer’s. They form tangles that block the communication between the brain’s neurons.

Neuroinflammation: A chronic inflammation in the brains of people with Alzheimer’s disease. It may be caused by a buildup of cells in the brain that normally are designed to clear out debris, including the proteins that form harmful plaques.

Neurologist: Physician trained to diagnose and treat nervous system disorders.

Neurons: These cells, also called nerve cells, receive sensory input from the world and send commands to the muscles. These normal activities are blocked by Alzheimer’s.

Neuroplasticity: The brain’s ability to adapt, change and modify its structure and function throughout life and in response to experience.

Neuropsychologist: Physician specializing in evaluating and managing brain problems.


Onset: This marks the beginning of a disease.

Oxidative stress: Damage to cells is caused when excess oxygen free radicals overwhelm a cell’s normal antioxidants, causing damage to those cells. This may be a factor in dementia.


Pacing: People living with Alzheimer’s may become worried, restless or agitated. They may wander back and forth to the point of exhaustion.

Paranoia: Another common symptom of dementia or Alzheimer’s, this is fear and suspicion of someone else and is not based on fact.

Parkinsonism: Neurologic condition characterized by decreased bodily movement, postural instability, rigidity and tremors.

Positron emission tomography: Imaging technology, also called a PET scan, uses small amounts of a radioactive substance to measure specific activity in the brain. 

Pillaging: An indicator of cognitive decline, this is taking things that belong to someone else.

Plaques: Deposits of beta-amyloid proteins in the brain. In people with Alzheimer’s disease, these deposits collect between neurons and disrupt cell function.

Prognosis: What a physician determines is likely to happen over time with a disease.

Progressive disorder: Physical disease or condition that gets worse over time.

Psychiatrists: Medical doctors specialize in treating behavioral, emotional or mental disorders. They can prescribe medications and provide counseling. 

Psychologists: Counselors who specialize in “talk therapy” to help people understand their emotions and learn ways to manage their challenges. They usually have advanced degrees but cannot prescribe medicine.

Psychosis: An irrational or disturbed state of mind, which can include delusions and hallucinations.

Repetitive behavior: Any behavior that is repeated over and over. Among people with Alzheimer’s, this may take the form of outbursts or repeated questions or stories, or certain activities.

Respite care: A way to provide caregivers a respite, or temporary relief, from their duties. Respite care can take the form of adult day care, in-home assistance or short nursing home stays.

>> Read “What is Respite Care?

Risk factor: A factor, such as genetics or injury, that makes a person more likely to develop a disease or condition.


Shadowing: Some with dementia or Alzheimer’s may follow, interrupt or mimic other people.

Side effect: A problem linked to treatment, which may be minor or more serious.

Skilled nursing care: Medical care and services provided by licensed nurses.

Sundowning: Sometimes called sundowners syndrome. It is a state of confusion that often occurs in the late afternoon or early evening in people with Alzheimer’s, causing aggression, anxiety, confusion or inability to follow directions. 

>> Read “Understanding Sundowners Syndrome in People with Dementia

Support group: Caregivers, family, friends, patients or others who meet with a facilitator to talk about their challenges, emotions and experiences, and to seek solutions.

Suspiciousness: A growing mistrust as people with Alzheimer’s disease experience a worsening memory.

The Complete Guide to Dementia for Caregivers Cover

The Complete Guide to Dementia for Caregivers

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Tangles: Also called neurofibrillary tangles, these are fibers twisted inside the brain’s cells. They primarily consist of a protein called tau and interfere with the healthy function of the brain.

Tau: Protein that occurs naturally in the structure of nerve cells. Abnormal tau proteins can be found in the tangles of plaque in the brains of people with Alzheimer’s disease.

Trigger: Something that may set off a particular behavior. Those with dementia or Alzheimer’s may need to be protected from triggers to harmful behavior.

Trustee: A financial institution or person appointed to manage the assets of a living trust.


Vascular dementia: A general difficulty with judgment, memory, planning, reasoning and other processes. It can be caused by an impaired blood flow to the brain caused by stroke or other conditions, such as diabetes or high blood pressure.


Wandering: According to the Alzheimer’s Association, 60% of people with dementia will wander. People living with Alzheimer’s or dementia may become disoriented, even in familiar places, and can forget their name and address. 

>> Read “How Senior Living Communities Provide Safety

Will: Legal document outlines how someone wants their estate to be handled after they die. 

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