Dementia is the loss of cognitive functioning — thinking, remembering, and reasoning — to such an extent that it interferes with a person’s daily life and activities. Some people with dementia cannot control their emotions, and their personalities may change. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living, such as feeding oneself.
Dementia affects millions of people and is more common as people grow older (about one-third of all people age 85 or older may have some form of dementia) but it is not a normal part of aging. Many people live into their 90s and beyond without any signs of dementia.
There are several different forms of dementia, including Alzheimer’s disease, which is the most common.
Signs and symptoms of dementia result when once-healthy neurons (nerve cells) in the brain stop working, lose connections with other brain cells, and die. While everyone loses some neurons as they age, people with dementia experience far greater loss.
The signs and symptoms can vary depending on the type and may include:
People with intellectual and developmental disabilities can also develop dementia as they age, and in these cases, recognizing their symptoms can be particularly difficult. It’s important to consider a person’s current abilities and to monitor for changes over time that could signal dementia.
Dementia is the result of changes in certain brain regions that cause neurons (nerve cells) and their connections to stop working properly. Researchers have connected changes in the brain to certain forms of dementia and are investigating why these changes happen in some people but not others. For a small number of people, rare genetic variants that cause dementia have been identified.
Although we don’t yet know for certain what, if anything, can prevent dementia, in general, leading a healthy lifestyle may help reduce risk factors.
Various neurodegenerative disorders and factors contribute to the development of dementia through a progressive and irreversible loss of neurons and brain functioning. Currently, there is no cure for any type of dementia.
Types of dementia include:
Scientists are investigating how the underlying disease processes in different forms of dementia start and influence each other. They also continue to explore the variety of disorders and disease processes that contribute to dementia. For example, based on autopsy studies, researchers recently characterized another form of dementia known as LATE. Further knowledge gains in the underlying causes of dementia will help researchers better understand these conditions and develop more personalized prevention, treatment, and care strategies.
Other conditions that cause dementia or dementia-like symptoms include:
In addition, medical conditions such as tumors, vitamin deficiencies, medication side effects, or problems with the thyroid, kidney, or liver can also cause serious memory problems that resemble dementia. Some causes of dementia symptoms can be halted or even reversed with treatment. For example, normal pressure hydrocephalus often resolves with treatment.
The similarity in symptoms of various dementias can make it difficult to get an accurate diagnosis. But a proper diagnosis is important to get appropriate treatment.