How common is dementia? What to know about Rosalynn Carter's diagnosis, symptoms and causes.

Rosalynn Carter's family disclosed Tuesday that the former first lady has dementia, a condition that afflicts millions of Americans.

The family said she remains at home with her husband, former President Jimmy Carter, and visits with loved ones, according to a statement released via the Carter Center.

The family emphasized the former first lady's work to reduce the stigma around mental health during her time in the White House and in the decades that have followed.

"One in 10 older Americans have dementia, a condition that affects overall mental health," the statement said. "We recognize, as she did more than half a century ago, that stigma is often a barrier that keeps individuals and their families from seeking and getting much-needed support. We hope sharing our family's news will increase important conversations at kitchen tables and in doctor’s offices around the country."

Here's what to know about dementia, its causes and how it's related to Alzheimer's disease.

Is there a cure for dementia? Dementia is difficult and costly to diagnose. It’s even harder to study.

What is dementia? What are symptoms?

Dementia describes symptoms that generally include loss of memory and thinking and social abilities that can affect everyday activities. Carter's family disclosed few specifics about her condition.

Symptoms vary depending on the cause of dementia. Common symptoms include memory loss and difficulty communicating, reasoning, problem-solving, handling complex tasks and planning. Some lose coordination and experience confusion or disorientation.

Though about 1 in 3 adults ages 85 and older have some form of dementia, it is not a normal part of aging, according to the National Institute on Aging. Many people live into their 90s and beyond without the condition.

Though dementia generally involves memory loss, the symptoms can have several causes.

What are the causes of dementia?

Several diseases that cause dementia, some of them related to aging. Some are rare genetic conditions.

Alzheimer's disease is the most common type of dementia that deteriorates memory and thinking. More than 6 million Americans live with Alzheimer's disease, according to the Alzheimer's Association, including about 1 in 9 people over age 65.

According to the Alzheimer's Association and the Mayo Clinic, other forms of nonreversible dementia include:

• Vascular dementia, which is caused when blood vessels to the brain are damaged.

• Lewy body dementia, which describes a type of protein found in the brains of some people with dementia, including Parkinson's disease and some Alzheimer's patients.

• Frontotemporal dementia, which describes a group of disorders and often involves the loss of brain cells and connections in the frontal and temporal lobes of the brain. This type of dementia is linked to behavior and personality changes as well as difficulty understanding language.

Other conditions linked to dementia include Huntington's disease, Parkinson's disease and Creutzfeldt-Jakob disease, which is part of a group of rare fatal brain disorders known as prion diseases.

Frontotemporal dementia: What is it? Causes, symptoms, treatments

Dementia and Alzheimer's disease

Alzheimer's disease is characterized by proteins that form plaques and tangles in the brains of patients. Alzheimer’s is a degenerative brain disease the damages and kills brain cells. Memory and thinking lapses worsen as the disease advances.

A small percentage of cases are believed to be cause by a genetic mutation that can be inherited and in some cases trigger memory and thinking loss in younger adults. Another inherited gene, called apolipoprotein E4, increases the risk but does not guarantee someone will develop the disease later in life.

Pharmaceutical companies have spent hundreds of million of dollars on drugs that seek to either clear or prevent the growth of the abnormal plaques and tangles that form in the brains of patients.

In January, Eisai and Biogen received FDA approval to sell Leqembi for patients in the early stages of Alzheimer's disease. In 2021, Biogen's Aduhelm was the first to gain approval based on studies that delivered mixed results − an approval that prompted investigations from two U.S. House committees.

This article originally appeared on USA TODAY: Rosalynn Carter dementia: Signs, symptoms, causes and link Alzheimer's