Dementia is a slow, progressive decline in mental function including memory, thinking, judgment, and the ability to learn.
Typically, symptoms include memory loss, problems using language and doing activities, personality changes, disorientation, and disruptive or inappropriate behavior.
Symptoms progress so that people cannot function, causing them to become totally dependent on others.
Doctors base the diagnosis on symptoms and results of a physical examination and mental status tests.
Blood and imaging tests are used to determine the cause.
Treatment focuses on maintaining mental function as long as possible and providing support as the person declines.
Dementia occurs primarily in people older than 65. Dementia, particularly the disruptive behavior that often accompanies it, is the reason for more than 50% of admissions to nursing homes. However, dementia is a disorder and is not a part of normal aging. Many people over 100 do not have dementia.
Dementia differs from delirium, which is characterized by an inability to pay attention, disorientation, an inability to think clearly, and fluctuations in the level of alertness.
Dementia affects mainly memory, and delirium affects mainly attention.
Dementia typically begins gradually and has no definite beginning point. Delirium begins suddenly and often has a definite beginning point.
Age-related changes in the brain (also called age-associated memory impairment) cause some decline in short-term memory and slowing in learning ability. These changes, unlike dementia, occur normally as people age and do not affect the ability to function and do daily tasks. Such memory loss in older people is not necessarily a sign of dementia or early Alzheimer disease.
Mild cognitive impairment causes greater memory loss than age-associated memory impairment. It may also impair the ability to use language, think, and use good judgment. However, it, like age-associated memory impairment, does not affect the ability to function or do daily tasks. Up to half of people with mild cognitive impairment develop dementia within 3 years.
Dementia is a much more serious decline in mental ability and one that worsens with time. People who are aging normally may misplace things or forget details, but people who have dementia may forget entire events. People who have dementia have difficulty doing normal daily tasks such as driving, cooking, and handling finances.
Depression may resemble dementia, especially in older people, but the two can often be distinguished. For example, people with depression may eat and sleep little. However, people with dementia usually eat and sleep normally until later in the disease. People with depression may complain bitterly about their memory loss but rarely forget important current events or personal matters. In contrast, people with dementia lack insight about their mental impairments and often deny memory loss. Also, people with depression regain mental function after the depression is treated. However, many people have depression and dementia. In these people, treatment of depression may improve but not entirely restore mental function.
In some types of dementia (such as Alzheimer disease), the level of acetylcholine in the brain is low. Acetylcholine is a chemical messenger (called a neurotransmitter) that helps nerve cells communicate with one another. Acetylcholine helps with memory, learning, and concentration and helps control the functioning of many organs. Other changes occur in the brain, but whether they cause or result from dementia is unclear.