Dementia (dih-MEN-shuh) is a decline in mental ability that usually progresses slowly, causing problems with thinking, memory, and judgment. It is most often seen in the elderly and is caused by deterioration in parts of the brain. A person with dementia eventually has difficulty with the activities of everyday living, such as balancing a checkbook, reading, or working.

Jacob's Story: “Why Doesn't Grandpa Recognize Me?”

As Jacob sits in the hospital waiting room, he reminisces about this same day last year. His grandpa had taken him to the Baltimore Orioles' home opener to celebrate his 11th birthday. Since then, his grandfather had experienced a few small strokes (blockages in the blood vessels that supply oxygen and nutrients to the brain). The resulting loss of oxygen caused damage to parts of his grandpa's brain. Now his grandpa can barely talk or make any decisions for himself. Jacob's grandpa is 82 years old, but he almost seems like a little kid.

What Is Dementia?

Dementia is a term that refers to several different physiologic brain diseases, all of which affect the way brain neuron cells function; the symptoms of these brain diseases can overlap. In a healthy brain, neuron cells produce electrical and chemical impulses (signals), and the process of relaying these signals helps people think. In people with some form of dementia, this neuron relay process does not work correctly and thinking processes are impaired. Dementia has four common forms:

In addition, people who have Huntington disease, Parkinson's disease, or Creutzfeldt-Jakob disease may develop dementia during the later stages of their disease.

* or toxic (a problem with substances in the blood that are needed to nourish the brain).

Structural Causes of Dementia

The most common form of dementia is Alzheimer's disease, a condition in which abnormal structures (called plaques and tangles) accumulate in the brain's neuron cells and interfere increasingly with nerve cell function. Alzheimer's disease leads to a gradual loss of mental abilities, including memory, judgment, and abstract thinking, and to changes in personality. This disease usually affects people older than 65 years. Symptoms that appear before the age of 65 years are called early onset.

Successive strokes are the second-most-common cause of dementia. Strokes, which are caused by blockages in arteries that feed the brain, gradually destroy brain tissue. People who develop this condition often have a history of high blood pressure and/or diabetes * . Other structural causes of dementia include:

Infectious Causes of Dementia

People who have acquired immunodeficiency syndrome * (AIDS) sometimes experience dementia because the virus that causes AIDS can infect the brain. Another dementia-causing condition is Creutzfeldt-Jakob disease (CJD), a very rare and rapidly progressing disease that affects the brain. Researchers are not sure what causes CJD, although in some cases it appears to have been passed from human to human by contaminated surgical instruments. One form of the disease has been found in humans who have eaten beef from a cow infected with mad cow disease. Another cause of dementia is viral encephalitis (en-seh-fuh-LYE-tus), an inflammation of the brain that can be caused by certain viruses, particularly those transmitted to humans by the bite of a mosquito.

Metabolic and Toxic Causes of Dementia

How Common Is Dementia?

Dementia is mostly a disease of the elderly. Starting at age 65, the risk of developing dementia doubles every five years. According to the Alzheimer's Association, in people 85 years and older, between 25 and 50 percent show signs of dementia. It is one of the most common reasons for nursing home admissions in the United States. In 2015 more than 5.2 million people in the United States were estimated to be living with Alzheimer's disease. Worldwide, approximately 35 million people have dementia, a number that is expected to double by 2030. When dementia affects young people, it is usually the result of an injury or some other condition that causes brain damage.

How Do People Know They Have Dementia?

During the early stages of the disease, people may be aware they are becoming forgetful. However, for the most part, people who have dementia are not aware they have it. Family members and caregivers often notice changes in personality, frequent confusion, and reduced energy. Skills in thinking, reasoning, memory, and judgment begin to decline, as do language and motor (movement) skills.

How Do Doctors Diagnose and Treat Dementia?


Risk Factors That Can Increase a Person's Chance of Developing Dementia

Risk Factors That Can Increase a Person's Chance of Developing Dementia
SOURCE: National Institute of Neurological Disorders and Stroke. “Dementia: Hope through Research.” (accessed August 19, 2015). Table by Cenveo Publisher Services. © 2016 Cengage Learning®

In most cases, dementia cannot be cured, and it is likely to worsen over time, especially when a progressive disease such as Alzheimer's disease or Parkinson's disease is the cause. Medications can be prescribed that help to lessen aggressive behavior, memory loss, or confusion, but there is no cure.

Dementia is especially hard on family members and loved ones who remember the person as he or she once was. The loss of memory, increased helplessness, and personality changes can be especially difficult to witness and accept. However, family and friends play an important role in helping a person deal with dementia. Familiar faces, regular exercise, and a cheerful, familiar environment have all been shown to help people with dementia. Caregivers can also help people with dementia by establishing a routine and encouraging them to take part in low-stress activities, eat healthy, and exercise regularly. Large calendars and clocks help people with dementia keep track of the day and time. Reminders from family, friends, or other caregivers about what is going on, who they are, and where the person is can also be helpful.

Can Dementia Be Prevented?


Many dementia-causing conditions are named after the physicians or scientists who discovered them.

Alois Alzheimer (1864–1915) was the German physician who published an article on a “new disease of the cortex” (the outermost or “reasoning” portion of the brain) in 1907. The disease is now called Alzheimer's disease.

James Parkinson (1755–1824) was the English physician who published “Essay on the Shaking Palsy” in 1817, one of the first articles on the disease later named for him.

George Huntington (1850–1916) was an American doctor from Ohio whose paper on hereditary chorea (kor-EE-uh) (a condition of uncontrolled, rapid movements) published in 1872 made him famous because of its accurate and complete descriptions of this disease. The condition later became known as Huntington chorea or Huntington disease.

Hans Gerhard Creutzfeldt (1885–1964) and Alfons Jakob (1884–1931) were German physicians who, during the 1920s, first described the brain disease later known as Creutzfeldt-Jakob disease.

Carl Wernicke (1848–1905) was a German physician whose 1881 Textbook of Brain Disorders first described a nervous system condition caused by insufficient amounts of a vitamin known as thiamine. Sergei Korsakoff (1854–1900) was a Russian psychiatrist who studied and described the connections among alcoholism, nerve inflammation, and mental symptoms. This condition later became known as Wernicke-Korsakoff syndrome.

See also AIDS and HIV Infection • Alzheimer's Disease • Brain Injuries • Creutzfeldt-Jakob Disease • Huntington Disease • Parkinson's Disease


Books and Articles

Abbey, Jenny, Laura Middleton-Green, Jane Chatterjee, and Murna Downs. End of Life Care for People with Dementia: A Person-Centered Approach. Philadelphia: Jessica Kingsley, 2015.

Mead, Rebecca. “The Sense of an Ending: An Arizona Nursing Home Offers New Ways to Care for People with Dementia.” New Yorker, May 20, 2013. (accessed December 3, 2015).

Planos, Josh. “The Dutch Village Where Everyone Has Dementia.” Atlantic, November 14, 2014. http://www.Theatlantic.Com/Health/Archive/2014/11/The-Dutch-Village-Where-Everyone-Has-Dementia/382195/ (accessed December 3, 2015).

Websites . “Understanding Dementia.” (accessed December 3, 2015).


Alzheimer's Association. 225 N. Michigan Ave., 17th Fl., Chicago, IL 60601-7633. Toll-free: 800-272-3900. Website: (accessed December 3, 2015).

American Geriatrics Society. 40 Fulton St., 18th Fl., New York, NY 10038. Telephone: 212-308-1414. Website: (accessed December 3, 2015).

Family Caregiver Alliance. 785 Market St., Suite 750, San Francisco, CA 94103. Toll-free: 800-445-8106. Website: (accessed December 3, 2015).

National Institute of Neurological Disorders and Stroke. PO Box 5801, Bethesda, MD 20824. Toll-free: 800-352-9424. Website: (accessed December 3, 2015).

* high blood pressure is a condition in which the pressure of the blood in the arteries is above normal. Also called hypertension.

* Parkinson's disease is a disorder of the nervous system that causes shaking, rigid muscles, slow movements, and poor balance.

* metabolic (meh-tuh-BALL-ik) pertains to the process in the body (metabolism) that converts food into energy and waste products.

* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This increase leads to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances in the body.

* degenerative (dih-JEN-er-uh-tiv) means progressively worsening or becoming more impaired.

* acquired immunodeficiency syndrome, or AIDS, is an infection that severely weakens the immune system. It is caused by the human immunodeficiency virus.

* CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoen-cephalopathy) is an inherited form of cerebrovascular disease that occurs when the thickening of blood vessel walls blocks the flow of blood to the brain. The disease primarily affects small blood vessels in the white matter of the brain.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)