Dementia is a general term that represents a group of diseases and illnesses that affect your thinking, memory, reasoning, personality, mood and behavior. The decline in mental function interferes with your daily life and activities. It’s estimated that about 50% of people age 85 and older have dementia. Current medications may help slow the mental decline.
Dementia is a description of the state of a person’s mental function and not a specific disease.
Dementia entails a decline in mental function from a previously higher level that’s severe enough to interfere with daily living. A person with dementia has two or more of these specific difficulties, including a decline in:
Dementia develops when the parts of your brain involved with learning, memory, decision-making or language are affected by infections or diseases. The most common cause of dementia is Alzheimer’s disease.
But other known causes of dementia include:
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Dementia is a description of the state of a person’s mental function and not a specific disease. Dementia is an “umbrella category” describing mental decline that’s severe enough to interfere with daily living.
There are many underlying causes of dementia, including Alzheimer’s disease and Parkinson’s disease. Alzheimer’s disease is the most common underlying cause of dementia.
Dementia is considered a late-life disease because it tends to develop mostly in people who are older.
About 5% to 8% of all people over the age of 65 have some form of dementia, and this number doubles every five years above that age. It’s estimated that as many as half of people 85 years of age and older have dementia.
The number of people age 65 and older who have Alzheimer’s disease and related dementias by race is:
The U.S. Centers for Disease Control and Prevention (CDC) estimate that 5 million U.S. adults age 65 or older have Alzheimer’s and related dementia. By 2060, the CDC projects that about 14 million people will have dementia, which is about 3.3% of the population.
Alzheimer’s disease is the sixth leading cause of death in the U.S. and the fifth leading cause of death in Americans age 65 and older.
One common misbelief about memory loss is that it always means you or a loved one has dementia. There are many causes of memory loss. Memory loss alone doesn’t necessarily confirm a diagnosis of dementia.
It’s also true that some memory changes are normal as a person ages (some neurons in your brain naturally die as we age). However, this type of memory loss isn’t functionally disabling; meaning, it doesn’t interfere with daily life.
Dementia interferes with your ability to function. Dementia isn’t forgetting where you left your keys. A person with dementia can have situations like forgetting what keys are used for. Dementia isn’t a normal part of aging.
Dementias can be divided into three groups:
Types of primary dementia include:
Other causes of dementia include:
Some conditions can cause dementia-like symptoms that can be reversed with treatment, including:
Early symptoms of dementia include:
Signs that dementia is getting worse include:
These symptoms are general symptoms of dementia. Each person diagnosed with dementia has different symptoms, depending on what area of their brain is damaged. Additional symptoms and/or unique symptoms occur with specific types of dementia.
Dementia is caused by damage to your brain. Dementia affects your brain’s nerve cells, which destroys your brain’s ability to communicate with its various areas. Dementia can also result from blocked blood flow to your brain, depriving it of needed oxygen and nutrients. Without oxygen and nutrients, brain tissue dies.
Damage to your brain results in different symptoms, depending on the area of your brain affected. Some dementias aren’t reversible and will worsen over time. Other dementias are due to other medical conditions that also affect your brain. Another group of health issues can result in dementia-like symptoms. Many of these conditions are treatable, and the dementia symptoms are reversible.
All of the possible causes of dementia are discussed in the question, “Are there different types of dementia?”
Confirming a diagnosis of dementia can be difficult. Many diseases and conditions can cause or lead to dementia. In addition, many of its symptoms are common to many other illnesses.
Your healthcare provider will:
They may also order tests, including laboratory tests, imaging tests and neurocognitive tests (thinking tests).
Neurologists and geriatricians may assist in making the diagnosis of dementia.
Laboratory tests rule out other diseases and conditions as the cause of dementia, such as infection, inflammation, underactive thyroid and vitamin deficiency (especially B12).
Sometimes, healthcare providers order cerebrospinal fluid tests to evaluate autoimmune conditions and neurodegenerative diseases, if warranted.
Your healthcare provider may order the following imaging tests of your brain:
During neurocognitive testing, your healthcare provider uses written and computerized tests to evaluate your mental abilities, including:
A mental health professional may check for signs of depression, mood changes or other mental health issues that might cause memory loss.
First, it’s important to understand the terms “treatable,” “reversible” and “curable.” All or almost all forms of dementia are treatable, in that medication and other measures can help manage your symptoms. However, most types of dementia can’t be cured or reversed, and treatments provide only modest benefits.
Fortunately, some types of dementia, like those brought on by treatable causes, may be successfully reversed. These dementia-like symptoms are caused by:
Dementias that aren’t reversible may still partially respond to medications that treat memory loss or behavior problems. These dementias include:
Drugs approved for the most common form of dementia, Alzheimer’s disease, include:
Healthcare providers use these drugs to treat people with some of the other forms of dementia.
Cholinesterase inhibitors and the NMDA receptor antagonist affect different chemical processes in your brain. Both drug classes have been shown to provide some benefit in improving or stabilizing memory function in some people with dementia.
Cholinesterase inhibitors manage the chemicals in your brain that allow messages to be sent between brain cells, which is needed for proper brain function. (Connections are lost as brain cells die when dementia worsens.) Memantine works similarly to cholinesterase inhibitors except it works on a different chemical messenger and helps the nerve cells survive longer.
Aducanumab targets amyloid proteins, which build up into the plaques seen in the brains of people with Alzheimer’s disease.
Although none of these drugs appear to stop the progression of the underlying disease, they may slow it down.
If other medical conditions are causing dementia or co-exist with dementia, healthcare providers prescribe the appropriate drugs used to treat those specific conditions. These other conditions include sleeping problems, depression, hallucinations and agitation.
Although dementia can’t be prevented, living a health-focused life might reduce risk factors for certain types of dementia.
Keeping blood vessels clear of cholesterol buildup, maintaining normal blood pressure, maintaining healthy blood sugar levels, staying at a healthy weight — basically, staying as healthy as you can — can keep your brain fueled with the oxygen and nutrients it needs to function at its highest possible level. Specific healthful steps you can take include:
Risk factors for dementia include:
Unfortunately, there isn’t a cure for the most common types of dementia. Currently, approved medications can, at best, slow the decline.
Your brain controls all of your body’s functions. When your brain functions decline, your overall health is eventually at risk. Many illnesses and conditions can happen as a result of having dementia.
Possible complications of dementia include:
Getting a diagnosis of dementia is certainly difficult to hear. Several types of dementia aren’t reversible. Others are a side effect of other serious diseases. Some dementia-like symptoms are due to conditions that can be treated and reversed.
Your healthcare team, which will probably include a neurologist and/or a geriatric-psychiatrist or a geriatrician, will order the needed tests to make the correct diagnosis. The medications available today focus on slowing the decline.
The goal is to maintain your or your loved one’s quality of life. Some people with Alzheimer’s dementia can live up to two decades, but each person has their own unique course. Researchers continue learning about the mechanisms that cause dementia and testing different methods to slow, and someday, hopefully, cure this disease.
Make an appointment with your healthcare provider if you or your friends and family see changes in:
Unfortunately, many types of dementia are conditions that worsen over time. When your brain doesn’t get the nutrients and oxygen it needs, or “junk” (abnormal proteins) blocks needed communication between the nerve cells of the brain, your brain tissue begins to die.
Alzheimer’s disease and other types of dementia usually begin with memory loss or lapses in judgment — things that can be lived with for a while. As you lose more and more brain function, functions vital to life begin to be affected. Vital functions include breathing, digestion, heart rate and sleep.
In the late stages of dementia, people can’t perform the tasks needed to keep their bodies alive. Brain damage and muscle weakness no longer allow even simple, needed movements. You can’t communicate, walk, talk, control your bladder or bowels, feed yourself, or chew or swallow food without help.
When you can’t care for yourself, move about, eat or drink enough to keep yourself hydrated and nourished, plus have mental decline, you leave yourself vulnerable to other illnesses. Pneumonia is one of these commonly seen illnesses in people with dementia. With a now frail body, a person may not be able to fight infections or even benefit from medication. The person’s pain and discomfort may outweigh treatment options that can only offer a short-term benefit.
At this point, many families choose hospice for end-of-life care. Hospice provides comfort care, with a focus on your quality of life over life-extending measures. Many people who pass away from a dementia-related condition don’t have that listed on their death certificate. This is because the complication from which they die — pneumonia, for example — is listed instead. Another reason may be that many people were never officially diagnosed with a dementia condition before they passed away.
There’s no easy way to answer this question. Dementia is an “umbrella” term that covers the many different types of underlying neurodegenerative diseases.
Each type of neurodegenerative disease has its own unique pattern and development in each person. Also, each person has a unique health profile. Some people may be relatively healthy and others may have several co-existing health issues. All of these factors play a role in the pace of decline in a person with dementia.
To answer more broadly, Alzheimer’s is the most common type of dementia. The average lifespan after the earliest symptoms is eight years. However, some people have lived as long as 20 years after an Alzheimer’s disease diagnosis.
No national dementia-related organizations define dementia by numerical stages. The Alzheimer’s Association does, however, define three stages of Alzheimer’s disease. Alzheimer’s disease dementia is the most common type of dementia. Some of the symptoms in these three stages are the same as symptoms for many of the forms of dementia.
People in the mild stage of Alzheimer’s disease are still able to function on their own. They may still drive, go to work and socialize. Some changes are happening that may or may not be noticed by the person with Alzheimer’s disease, but may be noticeable by close friends and family members.
Difficulties may include:
People in the middle stage of Alzheimer’s disease can be in this stage for many years. They can take part in everyday activities with help. Symptoms are more obvious.
Difficulties may include:
People in the late stage of Alzheimer’s disease can’t carry on conversations, lose awareness of what’s going on around them and can’t control their movement.
Difficulties may include:
A note from Cleveland Clinic
Learning early that you have a diagnosis of dementia allows you and your family to plan for a meaningful quality of life together and enables you to get your legal, financial and healthcare plans and desires in order. Your healthcare team, including clinicians, social workers, hospice and pastoral care members, is ready to provide education, support and care for you or your loved one. Ask your team for information on local dementia support groups, as well. Support groups can be very helpful for sharing care tips and providing comfort in knowing you’re not alone.
Last reviewed by a Cleveland Clinic medical professional on 03/12/2022.
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