What's the Difference Between Alzheimer's Disease and Dementia?

Because Alzheimer's usually progresses slowly, a person with the disease may experience a gradual decline in cognitive abilities over a period of seven to 10 years. (Image credit: lisafx | dreamstime.com)

Dementia is an umbrella term that refers to a group of physical and mental symptoms that are severe enough to interfere with a person's daily functions. The symptoms can be caused by various diseases or disorders.


Language difficulty, memory loss, poor judgment, confusion and changes in personality and mood are some of the symptoms of dementia, according to the Mayo Clinic. People with dementia may also lose their ability to solve problems or control their emotions. Other symptoms include difficulty with coordination and motor functions, paranoia, agitation, hallucinations and withdrawal from work or social activities.

In order to be diagnosed with dementia, the person must show serious problems with two or more brain functions, such as memory and language, according to the National Institute of Neurological Disorders and Stroke.

Doctors use a battery of screenings to determine the cause of the dementia. These include blood tests, mental status evaluations, neuropsychological testing and brain scans. In 90 percent of cases, doctors can accurately diagnose the cause of dementia symptoms , according to the Mayo Clinic.

Because the term dementia is used to categorize symptoms, it should not be confused with certain types of brain disorders that include dementia in their names. For example, the brains of sufferers of Lewy body dementia contain abnormal protein clumps that have also been found in brains of those with Alzheimer's disease and Parkinson's disease. But the disease, Lewy body dementia, has unique features that include fluctuations in confusion and clear thinking.

Vascular dementia is caused by brain damage as a result of arteries insufficiently pumping blood to the brain or heart, and symptoms (which can be temporary or progressively worsen) often begin suddenly, following a stroke or heart attack. Frontotemporal dementia is a group of diseases in which nerve cells in the frontal and temporal lobes of the brain which control personality, behavior and language gradually deteriorate, according to the Mayo Clinic.

Causes of general dementia include: Alzheimer's disease, Parkinson's disease, Huntington's disease, pugilistic Parkinson's syndrome (a condition caused by repetitive head trauma) and Creutzfeldt-Jakob disease. Some causes of dementia, such as a vitamin deficiency or drug interaction, are treatable and even reversible, according to the Mayo Clinic.

Alzheimer's disease

Alzheimer's is the most common cause of dementia, accounting for 50 percent to 70 percent of dementia cases in people ages 65 and older, according to the Centers for Disease Control and Prevention (CDC). As many as 5.3 million Americans are currently living with Alzheimer's disease, and it's the sixth-leading cause of death in the United States, according to the CDC.

However, Alzheimer's can be diagnosed with complete accuracy only after death, when the brain is thoroughly examined during an autopsy, according to the National Institutes of Health. A microscopic analysis of the deceased's brain tissue can reveal the plaques and tangles, which are masses of abnormal proteins, linked to Alzheimer's.

These proteins hinder brain function, affecting and limiting the parts of the brain that control memory, abstract thinking, judgment, behavior, movement and language. Alzheimer's causes worsening dementia symptoms as a result of its progressive destruction of a person's brain cells.

Because Alzheimer's usually progresses slowly, a person with the disease may experience a gradual decline in cognitive abilities over a period of seven to 10 years, according to the Mayo Clinic. Though symptoms generally appear after age 60, early-onset forms of the disease can occur, usually as the result of a gene, according to the National Institute on Aging.

Alzheimer's symptoms include getting lost, asking repetitive questions, experiencing difficulty handling money and paying bills, having poor decision-making skills, frequently misplacing items and undergoing personality changes. Those with Alzheimer's also tend to take longer than before to complete normal daily tasks. As Alzheimer's progresses and becomes severe, people may lose the ability to communicate and recognize oneself or family members.

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Remy Melina was a staff writer for Live Science from 2010 to 2012. She holds a bachelor’s degree in Communication from Hofstra University where she graduated with honors.