Mild cognitive impairment is a transition stage between the cognitive decline of normal aging and the more serious problems caused by Alzheimer's disease.

The disorder can affect many areas of thought and action — such as language, attention, reasoning, judgment, reading and writing. However, the most common variety of mild cognitive impairment causes memory problems.

According to the American College of Physicians, mild cognitive impairment affects about 20 percent of the population over 70. Many people with mild cognitive impairment eventually develop Alzheimer's disease, although some remain stable and others even return to normal.

The forgetfulness of normal aging is minor. You misplace your car keys or lose your car in the parking garage. Perhaps you can't remember the name of a former co-worker when you meet unexpectedly at the grocery store. This is nothing to worry about.

But red flags should go up if you start forgetting things you typically remember, such as doctor's appointments or your weekly pinochle game. This happens to everyone now and then, but if a pattern develops, it could be a symptom of mild cognitive impairment.

Commonly used criteria for a diagnosis of mild cognitive impairment are:

• Deficient memory, preferably confirmed by another person
• Essentially normal judgment, perception and reasoning skills
• Largely normal activities of daily living
• Reduced performance on cognitive tests, compared with other people of similar age and educational background

People with mild cognitive impairment may also experience:

• Depression
• Irritability
• Anxiety
• Aggression
• Apathy

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Brain shrinkage

Mild cognitive impairment often causes the same types of brain changes seen in Alzheimer's disease or other forms of dementia. The difference is in the extent of these changes, which is limited in mild cognitive impairment. These changes may include:

• Plaques, which are abnormal clumps of a protein called beta-amyloid
• Tangles, which are abnormal clumps of a protein called tau
• Shrinkage of the hippocampus, an area of the brain important for memory
• Strokes
• Lewy bodies, which are abnormal clumps of a protein that's associated with Parkinson's disease

• A specific change in a gene, called apolipoprotein E (APOE), which has been linked to Alzheimer's disease
• High blood pressure
• Diabetes
• Low levels of physical, social and mental activity
• Fewer years of education

People with mild cognitive impairment are three times more likely to develop Alzheimer's or other dementias than are those without such impairment. In fact, about half the people with mild cognitive impairment will progress to Alzheimer's disease within five years.

You will probably first discuss your symptoms with your family doctor. He or she may refer you to a dementia specialist — who may be a neurologist or a psychiatrist — for further evaluation.

What you can do
Appointments can be brief. To make the best use of the limited time, plan ahead and write lists of important information, including:

• Detailed descriptions of all your symptoms
• A list of all your medications and dosages, including nonprescription drugs and supplements
• Questions for the doctor, such as what tests or treatments he or she may recommend

What to expect from your doctor
You and your spouse, partner or someone else who knows you well may be asked:

• About any changes in your memory, personality and behavior
• What medications you're taking
• If you have a history of stroke, depression, alcohol abuse, head trauma or other neurological disorders

There is no specific test to confirm a diagnosis of mild cognitive impairment. Instead, your doctor will try to rule out other potential causes for your symptoms. Tests may include the following.

Neurological exam
As part of your physical exam, your doctor may also check for signs of Parkinson's disease, strokes, tumors or other medical conditions that can impair memory as well as physical function. The neurological exam may test:

• Reflexes
• Eye movements
• Balance
• Sense of touch

Mental status exam
A short form of this type of test can be done in less than 10 minutes in your doctor's office. You may be asked to:

• Name today's date and your location
• Copy a design, such as intersecting pentagons
• Follow a three-stage command
• Remember a list of three words
• Follow a written direction
• Count backwards by sevens
• Draw a clock

Longer forms of neuropsychological testing can take several hours. Your results are then compared with those of people from a similar age and education level. This can help distinguish normal from abnormal cognitive aging, and may help identify patterns in cognitive functions that provide clues to the underlying condition.

Lab tests
Simple blood tests can rule out physical problems that can affect memory, such as vitamin B-12 deficiency or an underactive thyroid gland.

Brain scans
Your doctor may order an MRI or CT scan to check for evidence of stroke or bleeding, and to rule out the possibility of a tumor.

There is no cure for mild cognitive impairment. Treatment of coexisting conditions, such as high blood pressure or depression, may help reduce cognitive problems. Scientists are searching for a treatment that may delay or prevent the progression to Alzheimer's disease or other dementias.

Alzheimer's drugs
During the first year of a three-year study, the rate of progression from mild cognitive impairment to Alzheimer's was much lower in the people who took donepezil (Aricept). However, that difference disappeared by the end of the study.

An Alzheimer's drug called galantamine (Razadyne) increases the risk of sudden death from heart attacks and strokes when used in people who have mild cognitive impairment.

High blood pressure drugs
People who have mild cognitive impairment are also more likely to have problems with the blood vessels inside their brains. High blood pressure can worsen these problems and cause memory difficulties. That's why it's important to keep your blood pressure at normal levels.

Antidepressants
Depression is common in people who have mild cognitive impairment, and depression, itself, can cause memory problems. Treating depression may help improve memory, while making it easier to cope with the changes in your life.

Study results have been mixed about whether the following activities can prevent or reverse mild cognitive impairment. But they can be part of a healthy lifestyle for older people with or without mild cognitive impairment.

• Exercise your muscles. Physical exercise may help reduce your risk of developing memory problems.
• Exercise your brain. Engaging in intellectually challenging activities has been associated with better memory skills.
• Avoid isolation. People who have a limited social network may have a much greater risk of developing dementia.
• Sleep well. Memory problems have been associated with sleep disorders. Discuss with your doctor any problems you have sleeping.

• Vitamin E. This antioxidant may help protect brain cells from the oxidative stress that appears to play a role in dementia, but it works no better than placebo in relieving the symptoms or delaying the progression of mild cognitive impairment.
• Ginkgo. This supplement appears to improve memory and concentration in older adults with no major memory problems, but it's still uncertain if ginkgo can help the memory problems associated with mild cognitive impairment.
• Music therapy. Older adults with Alzheimer's disease and other memory disorders have been successfully treated with music therapy to reduce their aggressiveness and to improve their mood and willingness to cooperate in daily activities.