What Is Dementia? 
Neurological DisordersDementia

What Is Dementia?

What Is Dementia?
Everyday Health
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Updated on March 30, 2026
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Dementia is not a disease. Instead, it’s a syndrome — a set of symptoms — that occurs when neurons (nerve cells) in the brain stop working, lose connections with other brain cells, and die.

Eventually, this leads to a loss of cognitive ability that’s significant enough to disrupt a person’s daily life — the definition of dementia, according to the National Institute on Aging.

Dementia ranges in severity from mild to severe. In the final stages, people become completely incapable of caring for themselves and require around-the-clock help with the most basic aspects of daily living.

Up to half of all men and women ages 85 and older (sometimes called “the oldest old”) have some form of dementia, yet experts don’t consider it a normal part of aging. Many people live into their nineties with their cognitive abilities intact.

Some people with dementia may be unable to control their emotions, or they may exhibit personality changes.

They may also grapple with hallucinations (seeing or experiencing things that don’t exist) or delusions (convictions not grounded in reality).

Dementia is different for everybody. Kalisha Bonds Johnson, PhD, RN, of Emory University’s Nell Hodgson Woodruff School of Nursing in Atlanta explains how.

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If You Know One Person With Dementia…

Dementia is different for everybody. Kalisha Bonds-Johnson, PhD, RN, of Emory University’s Nell Hodgson Woodruff School of Nursing explains how.

Stages of Dementia

People with dementia will always see their symptoms worsen over time, but not every person with the same type of dementia will decline at the same rate or experience the same symptoms at the same stage. Certain symptoms may never appear, stages may overlap, and symptoms may appear then disappear — each person is unique.

Outlining the stages of dementia, however, can be useful for people considering their future caregiving needs, hoping to enlist in clinical trials, or otherwise planning ahead.

Understanding the earliest stages of dementia can also help people make sense of puzzling brain glitches. In fact, researchers now identify a condition called mild cognitive impairment as a precursor to dementia for some people. This condition — which involves lapses in memory, language, thinking, and judgment that are noticeable to the person affected but not severe enough to impact everyday functioning — affects 12 to 18 percent of people ages 60 and over, according to the Alzheimer’s Association.

Each of the four most common types of dementia — Alzheimer’s, vascular dementia, Lewy body dementia, and frontotemporal disorders — has early symptoms that can be telling. Unlike the short-term memory loss of Alzheimer’s, for instance, vascular dementia may reveal itself as difficulty making plans or decisions.

In their advanced stages, though, symptoms of different dementia types all tend to become more like Alzheimer’s — with short-term memory loss, loss of awareness of surroundings, and difficulty communicating.

Signs and Symptoms of Dementia

Dementia involves impairment of core cognitive functions — such as memory, language skills, visual perception, the ability to focus and pay attention, and the ability to reason and solve problems — that’s severe enough to affect a person’s ability to do normal everyday tasks.

While short-term memory loss can be an early sign of dementia, particularly Alzheimer’s, different types of dementia may have different symptoms.

When vascular dementia develops after multiple small strokes, for instance, people may have difficulty with judgment and planning or may become increasingly unable to focus.

With Lewy body dementia, people may experience visual hallucinations — imagining they see things that aren’t there — or they may alternate between periods of alertness and confusion (day to day, or even hour to hour). Movement problems are also common, such as muscle rigidity, shaking or tremor, and loss of coordination.

Some people with frontotemporal dementia exhibit extreme changes in behavior and personality. They may begin making wildly inappropriate comments in social situations, for instance, or show a startling lack of inhibition.

 In a form of frontotemporal dementia called primary progressive aphasia, people have difficulty expressing their thoughts or finding words.

An accurate diagnosis is the first step toward getting the right kind of treatment and support for your dementia.

Causes and Risk Factors of Dementia

Dementia occurs when neurons (nerve cells) in the brain stop working, lose connections with other brain cells, and die. Researchers are still working to understand why this happens and are investigating the role that genetics, lifestyle, and environment all play as dementia risk factors.

Genes, which are passed down from parents to their offspring, are believed to play a role in almost every type of dementia. Yet except in rare cases of a single-gene mutation, people don’t inherit dementia directly. Instead, their odds depend on some combination of genetic, environmental, and lifestyle factors.

Certain kinds of dementia, though, appear to be more seriously affected by genetics. About 10 to 15 percent of people with the form of dementia called frontotemporal disorders (also known as frontotemporal dementia) have a strong family history.

Scientists have observed an association between certain kinds of dementia and high levels of proteins in the brain, as with the protein beta-amyloid (plaques) in Alzheimer’s disease.

Lewy body dementia, the third-most-common form of dementia, is associated with abnormal deposits of a protein called alpha-synuclein. In a healthy brain, alpha-synuclein helps neurons communicate. But when alpha-synuclein begins to clump inside neurons, forming so-called Lewy bodies, brain function is impaired, impacting thinking, movement, behavior, and mood.

Risk factors for Lewy body dementia include a family history of the condition, older age, having Parkinson’s disease, and having a condition called REM (rapid eye movement) sleep behavior disorder, which causes people to physically act out vivid, sometimes violent, dreams in their sleep.

Vascular dementia has been linked to damaged arteries that block the flow of blood to areas of the brain, depriving brain cells of the oxygen and nutrients they need to function. Sometimes, small blockages in blood vessels don’t cause any immediate symptoms, but can lead to dementia as more and more of the brain becomes damaged. Risk factors include atherosclerosis (buildup of fatty deposits in arteries), high cholesterol, high blood pressure, diabetes, and smoking.

At this point, the main risk factor that scientists have been able to identify for frontotemporal disorders is family history. But researchers have found genetic similarities between the underlying brain condition, frontotemporal degeneration, and amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease). Exploring those similarities may help scientists better understand and treat both illnesses.

How Is Dementia Diagnosed?

In general terms, diagnosis of dementia — identifying cognitive impairment — is typically much easier than identifying the underlying brain disorder. Symptoms of different types of dementia may overlap, and people can have more than one type of dementia at the same time.

The right diagnosis, though, is critical to getting the best treatment. Typically, this process starts with your primary care doctor, although specialists like a neurologist, neuropsychologist, or geriatrician may play a role.

The first task is ruling out treatable or reversible conditions with symptoms that can mimic dementia, such as depression or a thyroid problem. Your doctor will take a detailed medical history, conduct a physical exam and a neuropsychological assessment, and order lab tests.

Neuropsychological assessments help doctors see cognitive patterns that may indicate the presence of a particular brain disorder. These tests look at cognitive skills like memory, problem solving, language abilities, and focus.

Your doctor may also use imaging scans like magnetic resonance imaging, computed tomography, or positron emission tomography to look at your brain.

Treatment and Medication Options for Dementia

There is currently no cure for any of the progressive brain diseases that cause dementia. But there are several potential ways to treat dementia, depending on your underlying condition.

Medication Options

Disease-Modifying Monoclonal Antibody Therapies

Some newer drugs may slow down the process of cognitive decline in the early stages of Alzheimer’s disease. These drugs — lecanemab (Leqembi) and donanemab (Kisunla) — work by preventing plaques from clumping in the brain.

But there is no evidence that these drugs restore cognitive function that has already been lost, or prevent Alzheimer’s from progressing further. They have only been studied in people with mild cognitive impairment or early-stage Alzheimer’s — not in people with more advanced Alzheimer’s, or with other forms of dementia.

Disease-Modifying Monoclonal Antibody Examples

  • Lecanemab (Leqembi)
  • Donanemab (Kisunla)
This group of drugs remains controversial, with many experts raising concerns about their effectiveness, safety, and cost.

Other medications may reduce or stabilize some of the symptoms of dementia, at least for a while. Many have been approved by the U.S. Food and Drug Administration to treat Alzheimer’s disease, with clinical evidence that they can also help people with other forms of dementia.

Cholinesterase Inhibitors

People with Lewy body dementia, for instance, may take a group of drugs approved for Alzheimer’s called cholinesterase inhibitors. These medications may help with memory loss and confusion, as well as behavioral problems and hallucinations.

Cholinesterase Inhibitors Examples

  • Donepezil (Aricept)
  • Rivastigmine (Exelon)
  • Galantamine (Razadyne)

Blood Pressure and Cholesterol Medication

Treatment for vascular dementia typically focuses on addressing underlying issues with your heart and blood vessels, potentially slowing the rate of cognitive decline. Depending on your needs, you may be prescribed drugs to reduce your blood pressure, lower your cholesterol, prevent blood clots, or control your blood sugar if you have diabetes.

Antidepressants

Frontotemporal disorders are particularly difficult to treat with drugs because people can have adverse and even dangerous reactions to some medications. Certain antidepressants, though, may help curb social disinhibitions or impulsivity.

Cognitive Behavioral Therapy

Drug treatments aren’t the only way to address dementia. You may benefit from individual sessions with a mental health counselor to deal with feelings of stress or grief, or enlist the services of an occupational therapist to help make your home simpler and safer. Support group meetings with other people coping with dementia may also be an option.

There are also hundreds of clinical trials in the United States looking at dementia. Investigators working with people online and at centers around the country are studying both pharmaceutical and nonpharmaceutical interventions.

Participants in these clinical trials, including people with dementia and those at risk, can gain access to potential treatments before they’re in widespread use while also helping to find a cure for future generations.

Lifestyle Changes for and Prevention of Dementia

Lifestyle Changes for Dementia

Reduce Stress

People with dementia may improve their quality of life by focusing on their overall well-being and taking steps to reduce stress, simplify tasks, and reduce clutter at home.

Eat Well and Exercise

You can enhance your physical health by being physically active, eating well, and taking part in activities that involve social interaction or stimulate your brain.

Stay Social and Find Meaning

To boost psychological health, relationships are key. Having close friends who can provide emotional support can lift your feelings of well-being and self-worth.

People with dementia can also nourish their spiritual health by taking part in meaningful activities — whether that means outings with family and friends or quiet, meditative moments alone pursuing a hobby like yoga.

Caregivers can help improve quality of life for people with dementia by knowing the best ways to communicate and having strategies to overcome cognitive or behavioral challenges. For instance, presenting complex tasks a step at a time can lead to a greater chance of success and foster feelings of confidence.

Keep a Routine

Since many people with dementia tend to have worse symptoms in the evening, a calming routine before bed can help — meaning no noise from family members’ conversations or television, and no chores like meal cleanup. Plenty of night lights can also help with disorientation.

Prevention of Dementia

While your genetic makeup is known to play a role in dementia risk, in most cases, it’s just one piece of the puzzle. Researchers are actively investigating lifestyle and environmental factors that may increase or decrease your risk of developing dementia.

Keep Your Heart Healthy

To prevent vascular dementia, for instance, the best way to protect your brain may be to protect your heart. This means not smoking, getting enough physical activity, and keeping your blood pressure and cholesterol in check.

Stay Social

Scientists are actively investigating other lifestyle factors that can affect dementia risk. There is ongoing research on social engagement that analyzes factors like marital status and emotional connectedness. Some evidence supports an association between higher levels of social engagement and a lower dementia risk.

Get Better Sleep

Another area of study is the link between sleep and dementia. One study found that compared with older adults who reported typically getting six to eight hours of sleep, those who got less than five hours of sleep were about twice as likely to develop dementia after five years.

How Long Does Dementia Last?

Dementia is an ongoing condition that becomes more severe over time. How quickly your dementia progresses will depend on many factors, including the type of dementia you have, and varies from person to person.

For Alzheimer’s disease, the average length of time from diagnosis to death is four to eight years, but some people live as long as 20 years, according to the Alzheimer’s Association.

 A diagnosis at an older age typically means a shorter time before death.

People with vascular dementia typically live for about five years, and are more likely to die from a stroke or heart attack than from their dementia. People with Lewy body dementia typically live for about six years.

For people with frontotemporal dementia, the typical length of time from diagnosis to death is six to eight years. But those with motor neuron disease linked to this form of dementia typically live for only two to three years after diagnosis.

Complications of Dementia

Dementia is a progressive neurodegenerative syndrome that affects cognitive, behavioral, and functional abilities. As the disease advances, individuals frequently develop a range of medical and functional complications that significantly contribute to morbidity, hospitalizations, and mortality. Many of these complications arise from declining neurological function, impaired mobility, difficulty swallowing, and reduced ability to perform activities of daily living.

Aspiration Pneumonia and Respiratory Infections

One of the most serious complications of dementia is aspiration pneumonia, which occurs when food, saliva, or stomach contents enter the lungs. Progressive neurological decline often leads to dysphagia (swallowing difficulty), increasing the likelihood of aspiration. Dysphagia can also contribute to dehydration, malnutrition, and respiratory infections. In advanced dementia, aspiration pneumonia is a leading cause of hospitalization and death, highlighting the importance of monitoring swallowing function and respiratory health.

Malnutrition and Weight Loss

Malnutrition is highly prevalent among people living with dementia. Cognitive impairment can reduce appetite, disrupt eating behaviors, and impair the ability to recognize hunger or properly use utensils. In addition, dysphagia and behavioral symptoms such as agitation may further interfere with adequate nutritional intake. Studies have shown that poor nutritional status in dementia is associated with worse functional decline, increased morbidity, and higher mortality risk.

Falls and Functional Decline

As dementia progresses, individuals often experience impaired balance, reduced coordination, and decreased judgment, which substantially increases the risk of falls. Falls can lead to fractures, head injuries, and loss of independence. Functional decline in activities of daily living — including bathing, dressing, and mobility — further contributes to physical frailty and increased healthcare utilization.

Delirium and Neuropsychiatric Complications

People with dementia are particularly vulnerable to delirium, an acute state of confusion often triggered by infections, medications, or hospitalization. Delirium can accelerate cognitive decline, prolong hospital stays, and increase the risk of long-term functional deterioration. Neuropsychiatric symptoms such as agitation, hallucinations, and depression are also common complications that significantly impact quality of life and caregiver burden.

Pressure Injuries and Immobility

Advanced dementia frequently leads to decreased mobility and prolonged bed rest. Reduced movement increases the risk of pressure injuries (bedsores), muscle wasting, and deep vein thrombosis. These complications can worsen overall health status and increase the need for long-term care or institutionalization.

Increased Mortality

Complications such as pneumonia, malnutrition, and frailty contribute substantially to the elevated mortality observed in individuals with dementia. Research indicates that dementia independently increases mortality risk beyond the effects of other chronic conditions, emphasizing the importance of comprehensive medical management and supportive care.

The Takeaway

Dementia is cognitive impairment that significantly affects your daily life, and can be caused by several different patterns or processes in your brain. While dementia can’t be cured, it can be treated or managed through medications, changes in your home and daily routine, and a healthy lifestyle with social connections. Don’t hesitate to seek cognitive screening if you notice any concerning changes in thinking or behavior.

FAQ

What’s the difference between dementia and Alzheimer’s disease?
Dementia is cognitive impairment, from any cause, that significantly affects your daily life. Alzheimer’s disease is the most common type of dementia, and involves a specific pattern of brain changes involving abnormal protein clumps (plaques) and fibers (tangles).
The leading causes of dementia are Alzheimer’s disease, vascular dementia, Lewy body dementia, and frontotemporal dementia. While each of these dementia types has different risk factors, overall, you’re more likely to develop dementia the older you get after age 65.
Early symptoms of Alzheimer’s disease can include increased forgetfulness and difficulty following conversations. Vascular dementia often causes difficulty with judgment and planning, while Lewy body dementia can involve visual hallucinations and movement problems. Frontotemporal dementia may cause reduced inhibitions, drastic behavioral changes, and inappropriate behaviors.
Depending on the cause of dementia, different types of treatments may be beneficial. Certain drugs may slow the progression of Alzheimer’s disease, while other drugs are used to treat symptoms in multiple types of dementia. But dementia can’t be cured, and it gets worse over time.
There’s no sure way to prevent dementia, but most cases of dementia aren’t completely genetic and are somewhat related to lifestyle and environmental factors. You may be able to reduce your dementia risk by staying physically active, not smoking, and keeping your blood pressure and cholesterol under control.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  6. Frontotemporal Disorders: Causes, Symptoms, and Diagnosis. National Institute on Aging. January 22, 2025.
  7. Primary Progressive Aphasia. Mayo Clinic. February 7, 2025.
  8. Who Gets Frontotemporal Dementia? Alzheimer’s Society.
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  13. Espay AJ et al. Lecanemab and Donanemab as Therapies for Alzheimer's Disease: An Illustrated Perspective on the Data. eNeuro. June 28, 2024.
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