Because it creates subtle changes and has a broad set of symptoms, diagnosing mild cognitive impairment can be challenging for patients and physicians.
Essentially, MCI causes serious enough cognitive changes they may be noticed by the person affected or the people around them. The condition may not affect how the person carries out everyday activities, said a special report "More Than Aging: Understanding Mild Cognitive Impairment," contained within the Alzheimer's Association's annual facts and figures report.
It may be caused by a variety of factors, including anxiety, sleep deprivation or medication side effects. It may also develop because of a number of neurological, psychiatric or degenerative disorders, and may be caused by stroke, other vascular diseases or traumatic brain injury.
However, it may also develop because of brain changes associated with Alzheimer's disease.
MCI is an early stage of memory loss that may affect language or visual/spatial perception. The Alzheimer's Association estimates it affects 12-18 percent of people ages 60 and older.
"MCI is characterized by subtle changes in memory and thinking," the "More Than Aging" report states. "MCI is sometimes confused with normal aging, but it is not part of the typical aging process."
And, 10-15 percent of people who have MCI develop dementia each year, it said. (About a third of people with MCI develop dementia over five years.)
"However, some individuals with MCI revert to normal cognition or do not have additional cognitive decline," the report states. "Identifying which individuals with MCI are more likely to develop dementia is a major goal of current research. Distinguishing between cognitive issues, resulting from normal aging, those associate with the broad syndrome of MCI and this related to MCI due to Alzheimer's disease is critical in helping individuals, their families and physicians prepare for future treatment and care."
MCI is classified as one of two types, based on symptoms -- amnestic, in which memory issues are predominantly affected; and nonamnestic, in which other issues are affected, such as language, visuospatial abilities (perception of spacial relationships between objects), or executive functions (planning, remembering instructions and juggling multiple tasks).
"For example, a person with amnestic MCI could forget conversations or misplace items in their home, whereas a person with nonamnestic MCI could have difficulty keeping their train of thought during a conversation, finding their way around a once-familiar place or finishing everyday tasks, such as paying a bill," the report states.
An MCI diagnosis may require clinical exams and brief assessments to evaluate thinking and memory function. Assessments may measure changes in reasoning, problem-solving, planning, naming, comprehension and other skills.
Diagnosis may require ruling out other brain diseases, such as Parkinson's disease, dementia with Lewy bodies (associated with rapid eye movement sleep abnormalities), and conditions affecting blood vessels supporting the brain.
There is no treatment for MCI.
"In some cases, physicians may be able to identify reversible causes of cognition impairment, such as depression, medication side effects or sleep apnea," the report said. "They may also recommend exercise and healthy lifestyle interventions to help improve cognitive function and quality of life."
Post-diagnosis outcomes may vary depending on the underlying causes or other factors.
"According to new research, nearly half of people diagnosed with MCI did not progress to dementia and were cognitively normal when they were evaluated 2.4 years after their MCI diagnosis," the report said.
Alzheimer's disease-caused MCI has a specific underlying cause -- the "distinct biological changes lead to the damage and death of nerve cells in the brain."
Bio-markers, such as measure of beta-amyloid deposits, pathologic tau and others, can be detected in brain images or measured in cerebrospinal fluid.
These tests are unavailable to many patients.
"New blood tests are under development that provide simple, accurate, non- invasive detection of Alzheimer's disease bio-markers -- sometimes even before symptoms appear," the report shows. "For now, these blood-based bio-marker tests are for research use only and not available in everyday medical practice, but they hold promise for identifying patients at risk of MCI due to Alzheimer's disease earlier in the disease process."
Editor’s note: This is part two of an occasional series on Alzheimer’s disease.
See also:
Alzheimer’s care hasn’t changed much in decades
Previous coverage includes:
Alzhemer’s disease afflicts 6.5 million Americans
Losing a loved one to dementia is slow, painful