Dementia: Symptoms, Types, Causes, Treatment & Risk Factors (2024)

What is dementia?

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:

Memory.
Reasoning.
Language.
Coordination.
Mood.
Behavior.

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:

Vascular dementia.
Dementia with Lewy bodies.
Frontotemporal dementia.
Mixed dementia.
Dementia due to Parkinson’s disease.
Dementia-like conditions due to reversible causes, such as medication side effects or thyroid problems.

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What’s the difference between dementia and 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.

Who gets 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:

How common is dementia?

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.

Does memory loss mean dementia is starting?

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.

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Are there different types of dementia?

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.

Primary dementia

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.

Dementia due to other diseases and conditions

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.

Dementias due to reversible causes

Some conditions can cause dementia-like symptoms that can be reversed with treatment, including:

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, nonbenzodiazepine sedatives, narcotic pain relievers, statins and others. Ask your healthcare provider to review your medications if you have any dementia-like symptoms.
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).