What Is Mild Cognitive Impairment, And Why Should You Be Worried About It?

If you're worried about Alzheimer's disease, you should be concerned about Mild Cognitive Impairment first. That's because it's a leading indicator of serious problems. An understanding of MCI will help distinguish things you should worry about from normal aging.

What is Mild Cognitive Impairment?

MCI is defined by what it isn't. It's not normal and it's not dementia* -- it's somewhere in between. Since "normal" and "dementia" are themselves somewhat fuzzy, the dividing lines are blurry. There's no one test for MCI; a physician looks at the available evidence to make a diagnosis.

In normal brain aging, "fluid intelligence" -- the ability to handle new information or act creatively -- declines over time. But MCI affects the brain functions that normally age fairly well: the "crystallized intelligence" capabilities such as memory and vocabulary.

So MCI is an indication that something is wrong. The underlying problem is most often incipient Alzheimer's disease or cerebral vascular disease (which constricts blood flow to the brain), but there can be other causes.

A diagnosis of MCI should only be a first step, because MCI can have many outcomes. Progression to Alzheimer's is a real concern: 12% - 18% of patients with MCI develop Alzheimer's every year. Some drug treatments seem to slightly delay the onset of Alzheimer's. But not everyone with MCI develops Alzheimer's -- it could be caused by depression, or vascular problems, for instance -- and so it may be far more treatable. Unfortunately, while significant effort is going into developing the ability to predict what MCI patients will develop dementia (such as Alzheimer's), there is nothing usable yet. Further consultation with a physician is essential.

What To Look For

Much like Alzheimer's research, there are many paths being followed as investigators try to figure out what causes MCI. And like Alzheimer's, there are few definitive answers so far. But researchers have found several things -- some easily measured, some not -- that are tightly linked to MCI.

• Difficulty performing challenging cognitive tasks that haven't been a problem in the past. Worsening abilities to manage family finances, travel independently, or even prepare meals may indicate MCI (news story).
• Poor performance on a solitare-like game. Researchers found that playing FreeCell, a one person card game like solitare, may help diagnose MCI. People with MCI did poorly when their card placements were compared to the optimal move at each step of the game (news story).
• Hypertension. Hypertension is associated with a 70% greater risk of MCI in people 65+ (LifeTwo link; news story).
• Negative emotions and distress. People who are easily stressed, often anxious, or have negative emotions such as depression are 40% more likely to develop MCI than calmer people. (American Academy of Neurology press release).
• Diabetes. Older people with diabetes have a "significantly" higher risk of developing MCI. Diabetes could be associated with the buildup of plaques in the brain, and it's also linked to blood circulation problems such as stroke (news report)
• High blood sugar levels. Even for patients without diabetes, elevated blood sugar levels are associated with MCI. Although the mechanism isn't understood, the researchers emphasized the importance of treating anyone with abnormal blood sugar levels (news story).
• Difficulty identifying odors. Over a five year period, health adults who scored poorly on an odor identification test were 50% more likely to develop MCI than those who did well. It may be that the tangles associated with Alzheimer's affect the olfactory centers of the brain even before they create sufficient problems to trigger an Alzheimer's diagnosis (LifeTwo story; news link).
• High levels of uric acid in the blood. Although researchers don't understand why, higher levels of uric acid in blood tests are linked to MCI. They suggest that primary care physicians follow up such abnormal blood test results with patients to see if they have any MCI symptoms (news report).
• Heart problems. Patients with heart failure seemed 25% more likely to suffer from MCI than the general population -- likely a reflection of poor blood circulation to the brain (news story).

Prevention

Given the risk factors above, preventive steps are common sense. A healthy diet and regular exercise are the obvious starting points. These will help keep blood pressure, cardiovascular disease, and diabetes risk at bay.

There is evidence that frequent cognitive activity is associated with reduced risk of MCI. Reading a newspaper or playing a mentally challenging game may help (LifeTwo link; American Academy of Neurology press release). Although there are those who challenge these claims, even they agree that it can't hurt.

---
Other Resources:

"Mild Cognitive Impairment," Pieter Jelle Visser, in "Principles and Practice of Geriatric Medicine."

The Mayo Clinic's "Mild Cognitive Impairment" page.

* "dementia" is not a disease, but a group of symptoms or serious problems with two or more brain functions.