Alzheimer's blog

Alzheimer's, dementia and MCI overlap, but have different meanings

By Angela Lunde March 3, 2012

From time to time it's good to try and sort out the confusion among the terms mild cognitive impairment (MCI), dementia and Alzheimer's.

Cathy and several others asked about this in recent postings. Be assured that it's perfectly understandable if you're confused. The terms are often used interchangeably and can have varying interpretations even by healthcare professionals. Yet, their meanings are distinctly different. Let me attempt to clarify.

As we age, each of us has some changes in our thinking and memory, sometimes coined "senior moments." You may forget a person's name or a word, but recall it later in the day. You might misplace your glasses, keys, or wallet occasionally. Or maybe you find that you need to make lists more often to remember appointments or tasks. These changes in memory are generally minor and don't disrupt your ability to work, live independently, maintain normal activities and a social life.

MCI is used when cognitive changes (generally memory) are more frequent or exceed what's expected for an individual at a particular age. It can be thought of as a stage between normal forgetfulness due to age and the development of dementia.

In MCI, memory problems may be minimal to mild, and hardly noticeable to the individual. Writing reminders and practicing specific strategies can help a person compensate for these mild changes.

Symptoms of MCI can include:

  • Difficulty performing more than one task at a time
  • Difficulty solving complex problems or making decisions
  • Forgetting recent events or conversations
  • Taking longer to perform more difficult mental activities

Maybe most important is that a diagnosis of MCI means you're able to perform your usual daily activities with minimal change and little difficulty. When this is no longer the case, dementia may be the appropriate term to describe the condition.

Dementia isn't a specific disease. Instead, it describes a group of symptoms affecting intellectual and social abilities severe enough to interfere with daily functioning.

Memory loss generally occurs in dementia, but memory loss alone doesn't mean dementia. Dementia implies there are problems with other brain functions as well, and that more than one dementia symptom is present.

Symptoms of dementia can include:

  • Memory loss
  • Language problems
  • Inability to learn or remember new information
  • Difficulty with planning and organizing
  • Difficulty with coordination and motor functions
  • Personality changes
  • Inability to reason
  • Changes in behavior
  • Apathy or loss of interest in activities
  • Paranoia

Dementia symptoms can be due to many things such as an underactive thyroid, vitamin deficiency, brain tumors and depression. Even certain medications can cause dementia symptoms. However, if during a medical evaluation these reversible causes of dementia are ruled out, the probable cause of dementia symptoms may be due to Alzheimer's.

Alzheimer's causes brain changes that gradually get worse. Two abnormal structures called plaques and tangles are prime suspects in damaging and killing nerve cells, causing a steady decline in memory and mental function.

In older folks, Alzheimer's is the most common cause of progressive dementia symptoms. Symptoms are similar to the dementia symptoms listed above, which is why the terms are often used interchangeably. However, dementia is simply a set of symptoms, whereas Alzheimer's describes what is causing the symptoms.

Another reason it gets confusing is because the lines between normal age-related memory loss and mild cognitive impairment are blurred and overlap, as are the lines between MCI and early stage dementia caused by Alzheimer's.

But unlike Alzheimer's — where cognitive abilities gradually decline — persons with MCI may remain stable for years. And while not all persons with MCI go on to develop Alzheimer's, almost all cases of Alzheimer's start with MCI.

It's important to note that persons with MCI do have an increased risk of going on to develop Alzheimer's disease (or another form of progressive dementia).

However, science isn't able to predict whether someone with MCI will progress, remain stable or improve. Current research is focusing on models to predict who will get Alzheimer's and who won't, and on determining which folks with MCI will go on to develop Alzheimer's.

In the support groups here at Mayo Clinic, we often say to caregivers and persons with MCI or early stage dementia: Hope for the best but plan for the worst.

My message to you is to prepare for the possibility that things will progress — educate yourself, put plans and wishes in order, remain active and engaged, and get support. The Alzheimer's Association has a great booklet called "Living Well with MCI or Early Dementia."

You can find it at:

And remember, planning for the future is not the same as living in the future. Your life is today — the present moment is all any of us have for certain.

March 03, 2012