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.
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.
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:
Primary (diseases and conditions in which dementia is the main illness).
Secondary (dementia due to another disease or condition).
Reversible dementia-like symptoms caused by other illnesses or causes.
Types of primary dementia include:
Alzheimer’s disease: This is the most common type of dementia. Two abnormal proteins build up in your brain: tau and amyloid proteins. These proteins disrupt communication between nerve cells in your brain. Nerve cells die, starting in one area and spreading as more nerve cells die in other areas. Symptoms include short-term memory loss, confusion, personality and behavior changes. Trouble talking, remembering distant memories and issues with walking happen later in the disease. Alzheimer’s disease mainly affects adults who are older — up to 10% of those over age 65 and about 50% of people older than 85 have the disease. Family history is an important risk factor. Approximately 60% to 80% of people with dementia have this type.
Vascular dementia: This is the second most common type of dementia. It’s caused by conditions such as strokes or atherosclerosis, which block and damage blood vessels in your brain. Symptoms include memory problems, confusion and trouble concentrating and completing tasks. The decline may appear suddenly (following a major stroke) or in steps (following a series of mini strokes). Risk factors include high blood pressure, diabetes and high cholesterol levels. About 15% to 25% of people with dementia have vascular dementia.
Lewy body dementia: This condition involves the buildup of clumps of proteins — called Lewy bodies — in your brain’s nerve cells. Lewy bodies damage nerve cells. Symptoms include movement and balance problems, changes in sleep patterns, memory loss, planning and problem-solving difficulties, and visual hallucinations and delusions. About 5% to 10% of dementias are Lewy Body dementia.
Frontotemporal dementia (FTD): This dementia results from damage to the frontal and temporal lobes of your brain. The damage is caused by the buildup of abnormal proteins in these areas. It causes changes in social behavior, personality, and/or loss of language skills (speaking, understanding or forgetting the meaning of common words) or motor coordination. FTD is a common cause of early dementia, often occurring in people between the ages of 45 and 64. Between 5% and 6% of all dementias are FTD.
Mixed dementia: This is a combination of two or more types of dementia. The most common combination is Alzheimer’s disease with vascular dementia. It’s most common in people 80 years of age and over. It’s often hard to diagnose because symptoms of one dementia may be more obvious and/or many symptoms of each type overlap. The decline is faster in people who have mixed dementia compared with those who only have one type.
Other causes of dementia include:
Huntington’s disease: A single defective gene causes this brain disorder. The disease causes a breakdown in your brain’s nerve cells, which causes body movement control problems, as well as thinking, decision-making and memory trouble, and personality changes.
Parkinson’s disease: Many people in the later stages of Parkinson’s disease develop dementia. Symptoms include trouble with thinking and memory, hallucinations and delusions, depression and trouble with speech.
Creutzfeldt-Jakob disease: This rare infective brain disease affects about only 1 in 1 million people. An abnormal protein in your brain called prions causes the disease. These prions clump together and cause nerve cell death in your brain. Symptoms include problems with thinking, memory, communication, planning and/or judgment, confusion, behavior changes, agitation and depression.
Wernicke-Korsakoff syndrome: This brain disorder is caused by a severe thiamine (vitamin B1) deficiency. This can result in bleeding in key areas related to memory in your brain. It’s most commonly caused by alcohol use disorder but can also be due to malnutrition and chronic infection. Symptoms include double vision, loss of muscle coordination, and difficulty processing information, learning new skills and remembering things.
Traumatic brain injury: Repeated blows to your head can cause this injury. It’s most often seen in football players, boxers, soldiers and people who’ve had a vehicle accident. Dementia symptoms, which appear years later, include memory loss, behavior or mood changes, slurred speech and headaches.
Normal pressure hydrocephalus (NPH): This condition happens when cerebrospinal fluid (CSF) builds up in your brain’s spaces (ventricles). The excess buildup harms your brain. NPH can be caused by a brain infection, brain injury, brain bleed or previous brain surgery. Symptoms include poor balance, forgetfulness, trouble paying attention, mood swings, frequent falls and loss of bladder control. Your healthcare provider can drain excess fluid through the surgical placement of a shunt (tube).
Vitamin deficiency: Not getting enough vitamin B1, B6, B12 cooper and vitamin E in your diet can cause dementia-like symptoms.
Infections: Infections that can cause dementia-like symptoms include HIV infection, syphilis and Lyme disease. Symptoms reported with COVID-19 infection include “brain fog” and acute delirium. Because of the inflammation and stroke risk seen with COVID-19 infection, both short- and long-term cognitive effects are being investigated. Urinary tract infections (UTIs) and infections in your lungs in the elderly can also result in dementia-like symptoms. Other central nervous system infections and brain infections caused by fungi, bacteria and parasites can also cause cognitive symptoms.
Metabolic and endocrine conditions: Conditions that can mimic dementia include Addison’s disease, Cushing’s disease, low blood sugar (hypoglycemia) exposure to heavy metals (like arsenic or mercury), high calcium levels (hypercalcemia, often due to hyperparathyroidism), liver cirrhosis and thyroid problems.
Medication side effects: Some medications, in some people, can mimic dementia symptoms. These include sleeping pills, anti-anxiety drugs, antidepressants, anti-seizure drugs, antiparkinson drugs, narcotic pain relievers, statins and others.
Other causes: Other causes of dementia-like symptoms include brain tumors and subdural hematomas (brain bleeds between your brain’s surface and the covering over your brain).
Early symptoms of dementia 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.
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:
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:
Computed tomography (CT) and magnetic resonance imaging (MRI): CT uses X-rays and a computer to show detailed images of your brain. MRI uses magnets, radio frequencies and a computer to create detailed images of your brain. These imaging tests look for evidence of stroke, bleeding, tumors and fluid on your brain.
FDG-PET scan: This is a special type of brain scan that aids in determining brain function and cognitive decline by the pattern of how a type of glucose is absorbed by brain tissue, and is sometimes needed in specific diagnoses.
During neurocognitive testing, your healthcare provider uses written and computerized tests to evaluate your mental abilities, including:
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:
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:
Age: This is the strongest risk factor. Your chance of dementia increases as you age. Most cases affect people over the age of 65.
Family history: If you have biological parents or siblings with dementia, you’re more likely to develop dementia.
Down syndrome: If you have Down syndrome, you’re at risk of developing early-onset Alzheimer’s disease by middle age.
Poor heart health: If you have high cholesterol levels, high blood pressure, atherosclerosis or smoke, you increase your risk of dementia. These health problems, as well as diabetes, affect your blood vessels. Damaged blood vessels can lead to reduced blood flow and strokes.
Brain injury: If you’ve had a severe brain injury, you’re at a higher risk for dementia.
Unfortunately, there isn’t a cure for the most common types of dementia. Currently, approved medications can, at best, slow the decline.
What are the possible complications of dementia?
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: