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What Is Dementia?

It’s an umbrella term for a loss of memory and thinking skills that has various causessymptoms and treatments


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The 67-year-old woman arrived in the neurologist’s office in 2018 with concerns. Her memory used to be pretty goodshe told himbut she now had to write everything down to remember.​​

“Three years latershe was having trouble paying her bills and forgetting to take her medication,” recalls Andrew BudsonM.D.chief of cognitive and behavioral neurology and director of the Center for Translational Cognitive Neuroscience at the Veterans Affairs (VA) Boston Healthcare System. “She knew her memory wasn’t perfect but didn’t realize how much things had progressed.” Two years after thatshe was getting lost in her neighborhood and denying there was anything wrong with her memory. “As [patients] progressthey forget that they can’t remember. This is classic Alzheimer’s dementia.”​

Dementia is an umbrella term for conditions that impair a person’s ability to thinkreason and remember to levels that interfere with daily life. “Something in the brain goes wrong,” says Paul E. SchulzM.D.director of the Neurocognitive Disorders Center at the UTHealth Houston McGovern Medical School. “And it affects the person’s real world.” 

Although the risk of dementia rises a great deal after age 65it is not an inevitable part of aging. “It’s important to know it’s a disease; it’s not just normal aging or getting old,” says Melinda Powerdirector of the George Washington University Institute for Brain Health and Dementia. Dementia can be caused by several different diseasesincluding Alzheimer’s.

“At the core of any dementiabrain cells die,” she adds. In the early stagesthe person initially can compensateby using labeled pillboxesfor exampleor keeping notesand often still can function. But gradually — often over years — the person begins to have trouble doing things for themselves.

“There are multiple things going on in the brain,” Budson says. “What is common to all the dementias is that there is a process that is progressively killing brain cells. That is the commonality.” 

Types of dementia

Alzheimer’s disease is by far the most common formcausing 60 to 80 percent of dementia casesaccording to the Alzheimer’s Association. But there are other formseach with different causes and sometimes strikingly different symptoms. These include vascular dementiaLewy body dementia and frontotemporal dementia — which entered popular consciousness with news of actor Bruce Willis’ diagnosis in 2023. Some people can suffer from a combination of two or more of thesea condition known as mixed dementia. What these illnesses have in common is that they result from a progressive destruction of brain cellsaffecting thinkingmemory and behavior in various ways.

Signs and symptoms of dementia

Dementia is not the same as mild cognitive impairmentor MCIan early stage of memory and cognitive loss not serious enough to impair a person’s daily activities. Some people with MCI — 10 to 15 percent — will progress to full-blown dementia each year. Others will not.

“Mild cognitive impairment means there is some evidence that your thinking and memory are not as good as they should bebut not to the level where you can’t function independently,” Power says. “It’s true that people with MCI are more likely to develop dementia in their lifetime. It’s also true that many will revert back to normal cognition or never progress to dementia.”

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The Stats

  • More than 55 million people globally live with dementiaa number expected to rise to about 139 million by 2050according to the World Health Organization.
  • In the United Statesan estimated 7.2 million Americans have the most common form of dementiaAlzheimer’s disease. That number is projected to reach close to 14 million by 2060.
  • Early-onset Alzheimer’s is much less commonaffecting about 200,000 Americans younger than 65according to the Centers for Disease Control and Prevention.
  • Overallwomen are at greater risk of developing Alzheimer’s than men.
  • Black and Hispanic people are at greater risk for Alzheimer’s than white people.

People with dementiaon the other handhave progressed to a point where they can’t pay their bills, reliably take medications or drive safely. Eventuallythey will struggle to make a grocery list or work the TV remote. They may get lost in their own neighborhood and no longer recognize loved ones. They may “remember” experiences they never had. They will stop being able to dress themselves or go to the toilet.

With Alzheimer’speople “have trouble remembering the answers to questionsso they end up asking them again and again and again,” Budson says. “Other timespatients with Alzheimer’s can have false memories. For exampleone of my patients watched a TV show about going on a trip to Europethen told her family she went on this wonderful trip to Europe. She thought it all happened to her.”

Dementia in its various forms can impair judgmentaffect mood and personalityprompt odd behavior and distort how a person perceives what he or she sees.

One of Schulz’s Alzheimer’s patients had trouble telling where objects are in space. “She is a math professor who can still do all her equations.” She wrote them downso she could consult them. But she can’t find her phone on the tablehe says. “She can look at a doorknob but can’t tell you which way the door will open.”

Occasionally forgetting a name or misplacing a set of keys is normal as we age. The deficits associated with dementia are greaterand more devastatingsince they seriously affect how a person lives and functions.

“Many fear dementia more than a cancer diagnosis,” says Christine KistlerM.D.who specializes in geriatric medicine at the University of Pittsburgh Medical Center. In a waythat’s understandable. “We’ve made remarkable advances in diagnosing and treating cancerbut there is nothing we can do to cure dementia.”

What causes dementia?

Dementia occurs when neuronsor nerve cellsin the brain quit working. They lose their connection to other brain cells and eventually die. We all lose neurons as we agebut the loss is much greater in dementia. risk factors for dementiasuch as age and geneticsare impossible to change. But there are other factors that you can act upon — including diet and exercisehearing loss and social isolation.

How is dementia diagnosed?

There is no single diagnostic test to say whether a person has dementia. So doctors use a variety of tests and tools to learn what’s going on with the patientlook for signs of disease andmost importantlyrule out other treatable conditions that may be causing the cognitive problems. Brain scans may be usedas well as other tests — on blood and spinal fluid — to detect changes within the brain and identify the presence of certain substances associated with dementia. Paper-and-pencil or computer-based tests of memory and thinking are also often used to help make a dementia diagnosis.

​Dementia treatment and care

When it becomes impossible for a dementia patient to remain at home, the family often faces a wrenchingexpensive decision about whether to move their loved one into a care facility. “The point at which a person can’t stay at home is unique to that person,” Kistler says. “It tends to be when the behaviors can’t be managed safely at homeand that includes caregiver burnout and distress.”

Families don’t have to do this alone. Social workers affiliated with care facilities and doctors’ offices can often provide education on how to make this decision and how to make the transition in a way to have the best odds of success.

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The transition can be difficult and confusingbut there are steps families can take to ease the process. “Families can visit even if their loved ones don’t know them. A kind voice and caring actions can really help,” Kistler says. She also suggests taking the patient outside. “We know nature is helpful — or play them music. Put familiar things in their roomsuch as photos — there is no reason to leave sterile walls there.” Even small gestures to keep a patient busy are meaningful. Power’s husbanda nursefound a soothing way to comfort one elderly dementia patient who was anxious about being in a new facility. 

“She didn’t know where she was,” Power recalls. “My husband grabbed a stack of towels and said‘Could you fold the towels for the baby?’ It made her feel valued. She became calm. She had a purpose and felt good about it — and the feeling is what mattered in that moment.”

Reducing risk for dementia

Researchers say there are things you can do to reduce your risk, along with avoiding head injuries and maintaining hearing. These include stopping smokingeating a healthy Mediterranean- diet and exercisingcontrolling diabetes and managing heart disease riskssuch as high cholesterol and hypertension. “We believe that what’s good for the heart is good for the brain,” Power says.

Editor’s Note: This story has been updated to include new information.

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