Mild Cognitive Impairment (MCI)
MCI is a form of cognitive decline where changes are serious enough to be noticed by the affected individual and their family members, but not severe enough to interfere with normal activities of daily living.
Mild Cognitive Impairment (MCI) falls under theBrain HealthandHealthy Aging & Longevitycategories.
Mild cognitive impairment (MCI) describes a condition where people have poorer memory and thinking skills compared to other people their age but with minimal effects on typical daily tasks. This is sometimes caused by reversible factors like medication side effects, alcohol, poor sleep, and head injuries. But mild cognitive impairment is also the earliest detectable sign of the progressive cognitive decline associated with forms of dementia, including Alzheimer’s disease. Therefore, it is an important condition to detect to prevent the cognitive impairments from becoming sufficient to impair a person’s independence and ability to perform typical daily tasks.
People with mild cognitive impairment may lose things with increasing regularity, find it hard to make decisions and judgments, or notice increasing difficulty with language and remembering appointments and recent events. These symptoms are often also noticed by their friends and family. People with such symptoms should ask their doctor to test for signs that help identify the cause. This is important because some causes of mild cognitive impairment are unrelated to dementia and are treatable.
The signs of mild cognitive impairment include impaired memory, poor task completion, impaired nerve reflexes, and problems with movement, coordination, and balance.
The factors that can cause poor memory and thinking skills but are unrelated to dementia (e.g., medications, alcohol, poor sleep, and head injuries) are first ruled out with a medical history. The subsequent diagnosis of mild cognitive impairment involves several steps. Cognitive, neurological, and physical function tests are used to confirm poor memory and thinking skills and to identify problems with movement, coordination, and balance. Additional diagnostic tests may also be used to identify possible causes. For example, brain imaging tests like magnetic resonance imaging (MRI) or positron emission tomography (PET) can detect abnormalities in brain structure, while biochemical tests can detect abnormalities in tau and beta-amyloid protein levels in the cerebrospinal fluid (CSF).
The reversible causes of mild cognitive impairment (e.g., medication side-effects, alcohol, poor sleep, and head injuries) can often be treated by addressing those factors directly. For mild cognitive impairment associated with dementia (including Alzheimer's disease), there are no current pharmacological treatments. Instead, strategies are used to help people with mild cognitive impairment improve their cognitive function and maintain independence in performing their typical daily tasks. These strategies include maintaining regular physical and cognitive activities and social interactions. But more evidence is needed to determine their efficacy for preventing dementia.
The effects of several supplements have been studied in people with mild cognitive impairment. These include omega-3 fatty acids, probiotics, ginkgo biloba, B vitamins, vitamin C, vitamin D, vitamin E, etc. However, the current evidence does not support the use of any supplement in people with mild cognitive impairment for improving cognitive function or preventing dementia. That said, the current evidence is limited, and more high-quality large-scale randomized controlled trials are needed to make definitive conclusions.
Evidence suggests that higher circulating concentrations of methionine cycle metabolites (homocysteine, methionine, and S-Adenosylmethionine) are associated with greater cognitive decline in people with mild cognitive impairment. Since folate and vitamin B12 regulate methionine metabolism and can reduce plasma homocysteine concentrations, it is possible that their intake may influence cognitive decline. However, while lower folate and B12 concentrations are associated with poorer cognitive function, current evidence does not show that dietary folate or vitamin B12 intake prevents or treats mild cognitive impairment.
Other cohort studies show that consuming a mediterranean diet and a higher dietary intake of omega-3 fatty acids are associated with a lower risk of mild cognitive impairment. Long-duration randomized controlled trials are needed to prove the causality of these associations.
While all types of exercise improve cognitive function in people with mild cognitive impairment, resistance exercise appears most likely to prevent further cognitive decline. However, the efficacy of exercise in reducing the risk of dementia is currently unclear.
Transcranial direct current stimulation (electrically stimulating specific brain regions) can improve memory and cognitive skills in people with mild cognitive impairment. However, larger and higher-quality randomized controlled trials are needed to determine whether it can prevent or delay cognitive decline.
Computer or app-based cognitive training may also improve cognitive function in people with mild cognitive impairment. But, the current evidence is equivocal and higher-quality studies are needed.
Recently, drugs that reduce brain beta-amyloid accumulation (lecanemab, aducanumab, etc) have improved some aspects of cognitive function in people with early-stage Alzheimer's disease. Other drugs (memantine, donepezil, etc) are also sometimes used to treat symptoms in people with dementia. However, the safety and efficacy of these drugs have yet to be tested in people with mild cognitive impairment.
The causes of mild cognitive impairment can include the side effects of medications, alcohol, sleep deprivation, head injuries, and some neurological/psychiatric disorders. But mild cognitive impairment is also found in the early stages of neurodegenerative diseases like forms of dementia, including Alzheimer’s disease.
The exact cause of mild cognitive impairment associated with dementia and Alzheimer’s disease is unknown, but the risk factors include advanced age and diabetes. A family history of dementia or Alzheimer's disease also increases risk, suggesting that inherited genetic traits play a role. For example, people with the APOE-ε4 variant in the gene coding apolipoprotein E have a greater risk of developing mild cognitive impairment.
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