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Mild cognitive impairment (MCI) is the stage between the expected cognitive decline of normal aging and the more serious decline of dementia. It can involve problems with memory, language, thinking and judgment that are greater than normal age-related changes.
If you have mild cognitive impairment, you may be aware that your memory or mental function has "slipped." Your family and close friends also may notice a change. But these changes aren't severe enough to significantly interfere with your daily life and usual activities.
Mild cognitive impairment may increase your risk of later developing dementia caused by Alzheimer's disease or other neurological conditions. But some people with mild cognitive impairment never get worse, and a few eventually get better.
Symptoms
Your brain, like the rest of your body, changes as you grow older. Many people notice gradually increasing forgetfulness as they age. It may take longer to think of a word or to recall a person's name.
But consistent or increasing concern about your mental performance may suggest mild cognitive impairment (MCI). Cognitive issues may go beyond what's expected and indicate possible MCI if you experience any or all of the following:
- • You forget things more often.
- • You forget important events such as appointments or social engagements.
- • You lose your train of thought or the thread of conversations, books or movies.
- • You feel increasingly overwhelmed by making decisions, planning steps to accomplish a task or understanding instructions.
- • You start to have trouble finding your way around familiar environments.
- • You become more impulsive or show increasingly poor judgment.
- • Your family and friends notice any of these changes.
If you have MCI, you may also experience:
- • Depression
- • Irritability and aggression
- • Anxiety
- • Apathy
There's no single cause of mild cognitive impairment (MCI), just as there's no single outcome for the disorder. Symptoms of MCI may remain stable for years, progress to Alzheimer's disease or another type of dementia, or improve over time.
Current evidence indicates that MCI often, but not always, develops from a lesser degree of the same types of brain changes seen in Alzheimer's disease or other forms of dementia. Some of these changes have been identified in autopsy studies of people with MCI. These changes include:
- Abnormal clumps of beta-amyloid protein (plaques) and microscopic protein clumps of tau characteristic of Alzheimer's disease (tangles)
- Lewy bodies, which are microscopic clumps of another protein associated with Parkinson's disease, dementia with Lewy bodies and some cases of Alzheimer's disease
- Small strokes or reduced blood flow through brain blood vessels
Brain-imaging studies show that the following changes may be associated with MCI:
- • Shrinkage of the hippocampus, a brain region important for memory
- • Enlargement of the brain's fluid-filled spaces (ventricles)
- • Reduced use of glucose, the sugar that's the primary source of energy for cells, in key brain regions
Risk factors
The strongest risk factors for MCI are:
- • Increasing age
- • Having a specific form of a gene known as APOE-e4, also linked to Alzheimer's disease — though having the gene doesn't guarantee that you'll experience cognitive decline
Other medical conditions and lifestyle factors have been linked to an increased risk of cognitive change, including:
- • Diabetes
- • Smoking
- • High blood pressure
- • Elevated cholesterol
- • Obesity
- • Depression
- • Lack of physical exercise
- • Low education level
- • Infrequent participation in mentally or socially stimulating activities
Complications
People with MCI have a significantly increased risk — but not a certainty — of developing dementia. Overall, about 1 to 3 percent of older adults develop dementia every year. Studies suggest that around 10 to 15 percent of individuals with MCI go on to develop dementia each year.
Diagnosis
There is no specific test to confirm a diagnosis of mild cognitive impairment (MCI). Your doctor will decide whether MCI is the most likely cause of your symptoms based on the information you provide and results of various tests that can help clarify the diagnosis.
Many doctors diagnose MCI based on the following criteria developed by a panel of international experts:
- You have problems with memory or another mental function. You may have problems with your memory, planning, following instructions or making decisions. Your own impressions should be confirmed by someone close to you.
- You've declined over time. A careful medical history reveals that your ability has declined from a higher level. This change ideally is confirmed by a family member or a close friend.
- Your overall mental function and daily activities aren't affected. Your medical history shows that your overall abilities and daily activities generally aren't impaired, although specific symptoms may cause worry and inconvenience.
- Mental status testing shows a mild level of impairment for your age and education level. Doctors often assess mental performance with a brief test such as the Mini-Mental State Examination (MMSE). More-detailed neuropsychological testing may help determine the degree of memory impairment, which types of memory are most affected and whether other mental skills also are impaired.
- Your diagnosis isn't dementia. The problems that you describe and that your doctor documents through corroborating reports, your medical history, and mental status testing aren't severe enough to be diagnosed as Alzheimer's disease or another type of dementia.
Neurological exam
As part of your physical exam, your doctor may perform some basic tests that indicate how well your brain and nervous system are working. These tests can help detect neurological signs of Parkinson's disease, strokes, tumors or other medical conditions that can impair your memory as well as your physical function. The neurological exam may test:
- • Reflexes
- • Eye movements
- • Walking and balance
Lab tests
Blood tests can help rule out physical problems that can affect memory, such as a vitamin B-12 deficiency or an underactive thyroid gland.
Brain imaging
Your doctor may order an MRI or CT scan to check for evidence of a brain tumor, stroke or bleeding.
Mental status testing
Short forms of mental status testing can be done in about 10 minutes. During testing, doctors ask people to conduct several specific tasks and answer several questions, such as naming today's date or following a written instruction.
Longer forms of neuropsychological testing can provide additional details about your mental function compared with the function of others of a similar age and education level. These tests may also help identify patterns of change that offer clues about the underlying cause of your symptoms.
Treatment
Currently, no drugs or other treatments are approved specifically for mild cognitive impairment (MCI) by the Food and Drug Administration (FDA). However, MCI is an active area of research. Clinical studies are underway better understand the disorder and find treatments that may improve symptoms or prevent or delay progression to dementia.
Alzheimer's drugs
Doctors sometimes prescribe cholinesterase inhibitors, a type of drug approved for Alzheimer's disease, for people with MCI whose main symptom is memory loss. However, cholinesterase inhibitors aren't recommended for routine treatment of MCI.
Treating other conditions that can affect mental function
Other common conditions besides MCI can make you feel forgetful or less mentally sharp than usual. Treating these conditions can help improve your memory and overall mental function. Conditions that can affect memory include:
- High blood pressure. People with MCI tend to be more likely to have problems with the blood vessels inside their brains. High blood pressure can worsen these problems and cause memory difficulties. Your doctor will monitor your blood pressure and recommend steps to lower it if it's too high.
- Depression. When you're depressed, you often feel forgetful and mentally "foggy." Depression is common in people with MCI. Treating depression may help improve memory, while making it easier to cope with the changes in your life.
- Sleep apnea. In this condition, your breathing repeatedly stops and starts while you're asleep, making it difficult to get a good night's rest. Sleep apnea can make you feel excessively tired during the day, forgetful and unable to concentrate. Treatment can improve these symptoms and restore alertness.
