Mild Cognitive Impairment

What is the medical definition of dementia?

Dementia is a serious brain disorder that interferes with a person’s ability to carry out everyday tasks.

• The key feature of dementia is a decline in cognitive functions. These are mental processes such as thinking, reasoning, learning, problem solving, memory, language, and speech.
• Other features that occur frequently in dementia include changes in personality and behavior.
• Generally, these symptoms are not considered dementia unless they have continued unabated for at least 6 months.
• Dementia has many different causes. Some may be reversible, such as certain infections, drug intoxication, and liver diseases. Of the irreversible causes, the most common in older adults is Alzheimer's disease.
• Although dementia is frequently linked to old age (“getting senile”), it is not a normal part of aging. Even children with certain degenerative brain disorders can develop dementia.

What are the very first signs of Alzheimer's?

Alzheimer's disease usually begins with mild, slowly worsening memory loss. Many older people fear that they have Alzheimer's disease because they can’t find their eyeglasses or remember someone’s name.

• These very common problems are most often due to slowing of mental processes with age. It is not clear whether this is a normal part of aging.
• While this is a nuisance, it does not significantly impair a person’s ability to learn new information, solve problems, or carry out everyday activities, as Alzheimer's disease does.
• Medical professionals call this benign senescent forgetfulness, age-related memory loss, or mild cognitive impairment (MCI).

What are the stages of dementia?

Memory loss follows a specific pattern in Alzheimer's disease. The losses are mainly in short-term memory. This means that the person has problems remembering recent events.

• The person cannot remember what he did last week or instructions the doctor gave this morning for taking a new medicine.
• This often contrasts sharply with the person’s strong ability to remember minor details and events from many years ago.
• The memory loss is followed by many other cognitive and behavioral symptoms. Eventually, over many years, the person loses many mental and physical abilities and requires around-the-clock care.

What is mild cognitive impairment (MCI)?

MCI is a transitional zone between age-related memory loss and Alzheimer's disease. A person is often said to have MCI when he or she has Alzheimer's-like memory loss while the mind remains "sharp" otherwise.

• The person with MCI is able to think clearly, solve problems, learn new information, and communicate despite relatively minor memory loss.
• Memory loss in MCI is more severe than purely age-related memory loss.

There are other types of MCI, but the type involving short-term memory loss is the most common. Medical professionals call this type “amnestic” MCI. Amnestic has the same root as the word amnesia, meaning memory loss.

We are still learning about MCI. We don’t know how common it is, for example.

• About 5 million people in the United States have Alzheimer's disease, but we don’t know how many have MCI.
• Part of the problem is that the boundaries between age-related memory loss, MCI, and Alzheimer's disease have not been clearly defined.

What is the difference between mild cognitive impairment and Alzheimer's?

From studies in the brains of people with Alzheimer's disease or amnestic MCI, we know that the changes are similar. Therefore, amnestic MCI is generally considered to be due to an early form of Alzheimer's disease.

• Not everyone with MCI develops full dementia. However, people with MCI are more likely than other elderly people to develop Alzheimer's disease.
• At the moment, we do not know what factors contribute to progression from MCI to Alzheimer's disease.

We do not know exactly what causes MCI. We do know that most people with MCI eventually develop Alzheimer's disease. Like Alzheimer's disease, MCI is thought to be linked to abnormal deposits of certain proteins in the brain. Having low levels of certain brain chemicals called neurotransmitters is another feature of MCI and Alzheimer's disease.

A small number of cases of MCI are related not to Alzheimer's disease but to other causes of dementia. These include stroke, Parkinson disease, head injury, depression or extreme stress, drug interactions or side effects, or other medical conditions such as liver diseases or hormone disturbances. The number of conditions that can result in MCI and dementia is large.

The speed with which symptoms develop is often a clue to the cause of the MCI. MCI related to Alzheimer's disease develops gradually in most cases. MCI of some other causes may develop more quickly.

The most common symptom of mild cognitive impairment (MCI) by far is memory loss. Other, much less common symptoms include

• disturbances of language (word finding),
• attention (poor concentration), and
• orientation (disorientation in familiar surroundings).

The important thing to remember is that significant memory loss is not a normal part of aging. If you or a loved one is experiencing bothersome memory loss, especially short-term memory loss, a visit to your health care provider is warranted.

Pinpointing the cause of memory loss is a challenge to your health care provider. Alzheimer's disease and many other causes of dementia cannot be diagnosed with certainty by lab tests or brain scans. Your health care provider will ask you many questions about your symptoms and how they started, your other medical problems, your family’s medical problems, your medications, your habits and lifestyle, and your work and travel history.

The medical interview is followed by a careful physical examination and, possibly, lab tests and scans. Cognitive processes are tested by how well you answer certain questions and follow simple directions. Part of the process of making the diagnosis is ruling out conditions that do not fit the facts. At any time in this process, your health care provider may refer you to a specialist in diseases of elderly persons (gerontologist) or in diseases of the brain (neurologist or psychiatrist).

Lab tests

No specific laboratory test confirms the diagnosis of MCI. Most tests are done to rule out reversible conditions such as thyroid disorders, chemical imbalances, vitamin deficiencies, and infections.

Imaging studies

CT scan and MRI are used to "see" the brain and surrounding organs. Like lab tests, these brain scans do not give a definitive diagnosis of MCI. They may show abnormalities in the brain that are consistent with Alzheimer's-like dementia. They also are used to rule out potentially reversible causes of MCI.

Neuropsychological testing

Neuropsychological testing is the most accurate method of pinpointing and measuring a person’s cognitive problems and strengths. Neuropsychological testing is very useful in diagnosing MCI.

• The testing involves answering questions and performing tasks that have been carefully designed for this purpose. It is carried out by a psychologist.
• It addresses the individual’s appearance, mood, anxiety level, and experience of delusions or hallucinations.
• It assesses cognitive abilities such as memory, attention, orientation to time and place, use of language, and abilities to carry out various tasks and follow instructions.
• Reasoning, abstract thinking, and problem solving also are tested.

No treatment is known to stop or slow down memory loss in MCI. Medications used in Alzheimer's disease and some other kinds of dementia may help in MCI, but this has not been proven. One area of ongoing research is whether people with MCI do better without treatment—keeping in mind that medication can sometimes make cognitive symptoms worse. It is important that people with MCI be checked regularly to see if their condition has changed.

People with MCI should remain physically, socially, and mentally active to the greatest extent possible. Physical activity helps maintain a healthy weight, promotes relaxation and healthy sleep, and lifts the mood. A daily walk is appropriate for many people with MCI. Social interaction also fosters a positive mood and helps prevent depression. Many senior centers offer activities that promote social interaction. Mentally challenging activities, such as crossword puzzles and "brain teasers," may be helpful in holding off mental deterioration, but this has not been proven.

The medications used in Alzheimer's disease have also been tried in MCI. Those that have worked the best so far are the cholinesterase inhibitors.

• Cholinesterase is an enzyme that breaks down a chemical in the brain called acetylcholine. Acetylcholine acts as an important messaging system in the brain, but it is impaired in many people with MCI.
• Cholinesterase inhibitors stop the breakdown of this neurotransmitter. They increase the amount of acetylcholine in the brain and improve brain function in MCI.
• These drugs may improve or stabilize cognitive functions. They also may have positive effects on behavior and everyday activities.
• They are not a cure, but they may slow down conversion of MCI into dementia. In many people, the effect is fairly modest but definite. In others, these drugs do not have much of a noticeable effect.
• The effects are temporary, since these drugs do not change the underlying cause of the MCI, which remains unknown.
• Examples of cholinesterase inhibitors include donepezil (Aricept), rivastigmine (Exelon), and galantamine/galanthamine (Reminyl). These drugs have in effect replaced an older drug called tacrine (Cognex).

People with MCI should be checked regularly because of their increased risk for dementia.

There is no known way to prevent MCI or dementia. People who have a higher level of education or challenge themselves mentally may have a lower risk of MCI and Alzheimer's disease, but this has not been proven conclusively.

In a majority of people with mild cognitive impairment (MCI), the condition eventually worsens. In many, memory loss progresses to additional cognitive losses and behavior changes, eventually resulting in dementia.