Mild Cognitive Impairment
Mild cognitive impairment (MCI) is a condition characterized by a slight but noticeable and measurable decline in a person’s cognitive abilities, including memory and thinking skills, that is considered greater than normal age-related changes.
A person with MCI is at an increased risk of developing Alzheimer's disease or another type of dementia. Mild cognitive impairment causes cognitive changes that are serious enough to be noticed by a person (or those close to them), and detectable by cognitive assessment. They are not severe enough to impact activities of daily life, and therefore, do not meet the diagnostic criteria for dementia.
People living with mild cognitive impairment may either revert to normal, remain stable or progress to dementia. About 10 to 15 per cent of older adults with MCI progress to dementia every year.
It is estimated that about 15 to 20 per cent of adults aged 65 years and above have MCI. MCI can be classified into subtypes based on the skills affected, as amnestic and non-amnestic MCI, and as single domain and multiple domains MCI.
- MCI that primarily affects memory is known as amnestic MCI. A person may start to forget important information that he or she would previously have recalled easily, such as appointments, conversations or recent events.
- MCI that affects thinking skills other than memory is known as non-amnestic MCI. Thinking skills that may be affected include the ability to make decisions, judge the time or sequence of steps needed to complete a complex task or visual perception.
Causes & risk factors
The causes of MCI are not yet completely understood. Experts believe that many cases could result from brain changes occurring in the very early stages of Alzheimer's disease or other dementias.
The risk factors most strongly linked to MCI are the same as those for dementia, including advancing age, family history of Alzheimer's disease or another dementia, and stroke or cardiovascular disease. Other causes include medication side effects, traumatic brain injury, sleep deprivation, anxiety and depression.
How is MCI diagnosed?
Mild cognitive impairment (MCI) is a "clinical" diagnosis representing a physician’s professional judgment about the reason for a person's symptoms. Diagnosis is based on medical history, physical assessment, blood tests, mental status assessment, neurological examination and imaging studies.
A medical workup for MCI includes the following core elements:
- Thorough medical history (including input from a family member or a friend) where the physician documents current symptoms, previous illnesses and medical conditions, any family history of significant memory problems or dementia and changes in functioning.
- Assessment of independent function and daily activities, focusing on changes in a person's typical level of functioning.
- Cognitive assessment using brief tests designed to evaluate baseline memory, planning, judgment, ability to understand visual information and other key thinking skills. The Montreal Cognitive Assessment test or MoCA is a common tool. A MoCA score of 26 and above is considered normal. A score below 26 is considered consistent with MCI.
- Neurological assessment to check the function of nerves and reflexes, movement, coordination, balance and senses.
- Evaluation of mood to detect depression; symptoms may include problems with memory or feeling “foggy.” Depression is widespread and may be especially common in older adults.
- Blood tests and imaging of the brain's structure (CT, MRI, PET scans to exclude other causes of cognitive impairment).
If the workup does not show a clear clinical picture, the doctor may recommend neuropsychological testing, which involves a series of written or computerized tests to evaluate specific thinking skills.
Diagnostic criteria for MCI include the following:
- Concern regarding a change in cognition
- Impairment in one or more cognitive domains
- Preservation of independence in functional abilities
- Absence of dementia
Mood and behaviour changes in MCI
Mood and behaviour changes are present in 35 to 75 per cent of individuals with mild cognitive impairment. Depression, apathy and anxiety are the most common. Irritability and agitation may be present. Hallucinations and loss of inhibitions are less common.
People with MCI who exhibit mood and behaviour changes have an increased risk of progressing or converting into dementia.
Predictors of conversion
The most accurate predictors of dementia include:
- Neuropsychological tests showing a decline in episodic memory and long delay cued recall
- CSF biomarkers- low beta-amyloid 42, and elevated tau
- Shrinking or atrophy of hippocampus area of the brain (memory and learning centre) on MRI
- Hypometabolism (reduced glucose metabolism) as seen on FDG-PET
- White matter lesions (blood vessel changes in the white matter of the brain) on CT/MRI
What treatment options are available?
Currently, there are no medications to treat mild cognitive impairment. Pharmaceutical drugs approved to treat symptoms of Alzheimer's disease have not shown any lasting benefit in delaying or preventing the progression of mild cognitive impairment (MCI) to dementia. People diagnosed with MCI should be followed up every six months to determine if the symptoms have progressed.
- Cognitive interventions
- Cognitive stimulation – challenging the brain through active learning, solving puzzles, etc. to increase a person’s cognitive reserve
- Cognitive training – guided memory training, language training
- Cognitive rehabilitation – memory aids, skill-building and strategies to tackle real-world difficulties in order to improve, achieve or maintain everyday functioning
Mood and behaviour focus
- Efforts to improve mood through music, art, physical activity and socializing
Exercise and lifestyle factors:
- Regular exercise, Mediterranean diet, controlling cardiovascular risk factors such as high blood pressure, cholesterol, and diabetes; and participating in cognitively stimulating and socially engaging activities may help slow down cognitive decline.
MCI increases the risk of developing dementia at a later period, but it is not an inevitable consequence.
Researchers are working on new diagnostic tools that would help identify and measure underlying brain changes linked to specific types of dementia and help predict the outcome of MCI for each person.
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