See also
- Menopause-related cognitive impairment – similar symptoms, appears shortly after menopause, and can be treated with hormone replacement therapy [ citation needed ]
| Mild cognitive impairment | |
|---|---|
| Other names | Incipient dementia, isolated memory impairment |
| Specialty | Neurology |
| Symptoms | Can include memory impairments (amnestic) or cognitive problems like impaired decision making, language, or visuospatial skills (non-amnestic) |
| Usual onset | Typically appears in adults 65 or older |
| Types | Amnestic, non-amnestic |
| Risk factors | Age, family history, cardiovascular disease |
| Diagnostic method | Based on symptoms assessed by a clinical neuropsychologist through observations, neuroimaging, and blood tests |
Mild cognitive impairment (MCI) is a diagnosis that reflects a transitional state between normal aging and dementia, [1] especially dementia due to Alzheimer's disease (Alzheimer's dementia). [2] MCI may include both memory and non-memory neurocognitive impairments. [3] About 50 percent of people diagnosed with MCI have Alzheimer's disease and go on to develop Alzheimer's dementia within five years. MCI can also serve as an early indicator for other types of dementia, although MCI may also remain stable or remit. [4] Many definitions of MCI exist. A common feature of many of these is that MCI involves cognitive impairments that are measurable but that are not significant enough to interfere with instrumental activities of daily living. [1]
The DSM-5 introduces the concept of mild neurocognitive disorder (mNCD), which is designed to be largely equivalent to MCI. [5] The International Classification of Diseases (ICD-11) refers to MCI as "Mild Neurocognitive Disorder (MND)". [6] It is controversial whether MCI should be used as a diagnosis. [7]
MCI can present with a variety of symptoms, but is divided generally into two types. [4]
Amnestic MCI (aMCI) is mild cognitive impairment with memory loss as the predominant symptom; aMCI is frequently seen as a prodromal stage of Alzheimer's disease. [4] [3] [8] Studies suggest that these individuals tend to progress to probable Alzheimer's disease at a rate of approximately 10% to 15% per year.[ needs update ] [9] It is possible that being diagnosed with cognitive decline may serve as an indicator of MCI. [10]
Nonamnestic MCI (naMCI) is mild cognitive impairment in which impairments in domains other than memory (for example, language, visuospatial, executive) are more prominent. [4] [11] It may be further divided as nonamnestic single- or multiple-domain MCI, and these individuals are believed to be more likely to convert to other dementias (for example, dementia with Lewy bodies). [12]
Mild cognitive impairment (MCI) may be caused due to alteration in the brain triggered during early stages of Alzheimer's disease, to other causes, or to a combination of causes.[ better source needed ] [13] Brain damage, brain injury, delirium and prolonged substance abuse can cause MCI. HIV-associated neurocognitive disorder can cause MCI. Risk factors of both dementia and MCI are the same, and include: aging, genetics, and cardiovascular disease. [14]
The diagnosis of MCI requires clinical judgement, [9] possibly including clinical observation, neuroimaging, [15] blood tests and neuropsychological testing. MCI may be diagnosed differently by different clinicians using different definitions or criteria, but generally including: [16]
Magnetic resonance imaging can observe deterioration, including progressive loss of gray matter in the brain, from MCI to full-blown Alzheimer dementia. [17] A technique known as PiB PET imaging is used to show the sites and shapes of beta amyloid deposits in living subjects using a 11C tracer that binds selectively to such deposits. [18] Individuals with MCI may have increased oxidative damage in their nuclear and mitochondrial brain DNA. [19]
The American Academy of Neurology's (AAN) clinical practice guideline on MCI from January 2018 stated that clinicians should identify modifiable risk factors in individuals with MCI, assess functional impairments, provide treatment for any behavioral or neuropsychiatric symptoms, and monitor the individual's cognitive status over time. [4] It also stated that medications which cause cognitive impairment should be discontinued or avoided if possible. [4] Due to the lack of evidence supporting the efficacy of cholinesterase inhibitors in individuals with MCI, the AAN guideline stated that clinicians who choose to prescribe them for the treatment of MCI must inform patients about the lack of evidence supporting this therapy. [4] The guideline also indicated that clinicians should recommend that individuals with MCI engage in regular physical exercise for cognitive symptomatic benefits; [4] clinicians may also recommend cognitive training, which appears to provide some symptomatic benefit in certain cognitive measures. [4] Current evidence suggests that cognition-based interventions do improve mental performance (i.e. memory, executive function, attention, and speed) in older adults and people with mild cognitive impairment. [20] Especially, immediate and delayed verbal recall resulted in higher performance gains from memory training.
Diet improvements are likely beneficial to MCI. However, there is currently limited evidence to form a strong conclusion to recommend particular carbohydrate supplements in preventing or reducing cognitive decline in older adults with normal cognition or mild cognitive impairment. [21]
According to research conducted in England, people with MCI often do not receive adequate care and support in healthcare settings. This leaves them and their families in a limbo with uncertainty regarding their futures and the fear of possibly developing dementia. The lack of services also fails to point them to effective ways to prevent dementia such as exercise and social contact. Successful dementia prevention services would have to be tailored to people's preferences and backgrounds. [22] [23]
As MCI may represent a prodromal state to clinical Alzheimer's dementia, treatments for Alzheimer's disease could potentially be useful. [24] Of these, rivastigmine failed to stop or slow progression to Alzheimer's disease or to improve cognitive function for individuals with mild cognitive impairment; [25] donepezil showed only minor, short-term benefits and was associated with significant side effects. [26]
MCI does not usually interfere with daily life. [4]
The prevalence of MCI varies by age. [4] The prevalence of MCI among different age groups is as follows: 6.7% for ages 60–64; 8.4% for ages 65–69, 10.1% for ages 70–74, 14.8% for ages 75–79, and 25.2% for ages 80–84. [4] After a two-year follow-up, the cumulative incidence of dementia among individuals who are over 65 years old and were diagnosed with MCI was found to be 14.9%. [4]
Due to the emphasis shifting to the earlier diagnosis of dementia, more people are assessed who report memory problems. In turn this also leads diagnosing more people who might have MCI which is a risk factor for dementia. [22] [23] Globally, approximately 16% of the population over the age of 70 experiences some type of MCI.[ medical citation needed ]
Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform everyday activities. This typically involves problems with memory, thinking, behavior, and motor control. Aside from memory impairment and a disruption in thought patterns, the most common symptoms of dementia include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia ultimately has a significant effect on the individual, their caregivers, and their social relationships in general. A diagnosis of dementia requires the observation of a change from a person's usual mental functioning and a greater cognitive decline than might be caused by the normal aging process.
Dementia with Lewy bodies (DLB) is a type of dementia characterized by changes in sleep, behavior, cognition, movement, and regulation of automatic bodily functions. Memory loss is not always an early symptom. The disease worsens over time and is usually diagnosed when cognitive impairment interferes with normal daily functioning. Together with Parkinson's disease dementia, DLB is one of the two Lewy body dementias. It is a common form of dementia, but the prevalence is not known accurately and many diagnoses are missed. The disease was first described on autopsy by Kenji Kosaka in 1976, and he named the condition several years later.
Vascular dementia is dementia caused by a series of strokes. Restricted blood flow due to strokes reduces oxygen and glucose delivery to the brain, causing cell injury and neurological deficits in the affected region. Subtypes of vascular dementia include subcortical vascular dementia, multi-infarct dementia, stroke-related dementia, and mixed dementia.
Binswanger's disease, also known as subcortical leukoencephalopathy and subcortical arteriosclerotic encephalopathy, is a form of small-vessel vascular dementia caused by damage to the white brain matter. White matter atrophy can be caused by many circumstances including chronic hypertension as well as old age. This disease is characterized by loss of memory and intellectual function and by changes in mood. These changes encompass what are known as executive functions of the brain. It usually presents between 54 and 66 years of age, and the first symptoms are usually mental deterioration or stroke.
Neurocognitive functions are cognitive functions closely linked to the function of particular areas, neural pathways, or cortical networks in the brain, ultimately served by the substrate of the brain's neurological matrix. Therefore, their understanding is closely linked to the practice of neuropsychology and cognitive neuroscience – two disciplines that broadly seek to understand how the structure and function of the brain relate to cognition and behaviour.
Rapid eye movement sleep behavior disorder or REM sleep behavior disorder (RBD) is a sleep disorder in which people act out their dreams. It involves abnormal behavior during the sleep phase with rapid eye movement (REM) sleep. The major feature of RBD is loss of muscle atonia during otherwise intact REM sleep. The loss of motor inhibition leads to sleep behaviors ranging from simple limb twitches to more complex integrated movements that can be violent or result in injury to either the individual or their bedmates.
Donepezil, sold under the brand name Aricept among others, is a medication used to treat dementia of the Alzheimer's type. It appears to result in a small benefit in mental function and ability to function. Use, however, has not been shown to change the progression of the disease. Treatment should be stopped if no benefit is seen. It is taken by mouth or via a transdermal patch.
Cognitive disorders (CDs), also known as neurocognitive disorders (NCDs), are a category of mental health disorders that primarily affect cognitive abilities including learning, memory, perception, and problem-solving. Neurocognitive disorders include delirium, mild neurocognitive disorders, and major neurocognitive disorder. They are defined by deficits in cognitive ability that are acquired, typically represent decline, and may have an underlying brain pathology. The DSM-5 defines six key domains of cognitive function: executive function, learning and memory, perceptual-motor function, language, complex attention, and social cognition.
The mini–mental state examination (MMSE) or Folstein test is a 30-point questionnaire that is used extensively in clinical and research settings to measure cognitive impairment. It is commonly used in medicine and allied health to screen for dementia. It is also used to estimate the severity and progression of cognitive impairment and to follow the course of cognitive changes in an individual over time; thus making it an effective way to document an individual's response to treatment. The MMSE's purpose has been not, on its own, to provide a diagnosis for any particular nosological entity.
HIV-associated neurocognitive disorders (HAND) are neurological disorders associated with HIV infection and AIDS. It is a syndrome of progressive deterioration of memory, cognition, behavior, and motor function in HIV-infected individuals during the late stages of the disease, when immunodeficiency is severe. HAND may include neurological disorders of various severity. HIV-associated neurocognitive disorders are associated with a metabolic encephalopathy induced by HIV infection and fueled by immune activation of macrophages and microglia. These cells are actively infected with HIV and secrete neurotoxins of both host and viral origin. The essential features of HIV-associated dementia (HAD) are disabling cognitive impairment accompanied by motor dysfunction, speech problems and behavioral change. Cognitive impairment is characterised by mental slowness, trouble with memory and poor concentration. Motor symptoms include a loss of fine motor control leading to clumsiness, poor balance and tremors. Behavioral changes may include apathy, lethargy and diminished emotional responses and spontaneity. Histopathologically, it is identified by the infiltration of monocytes and macrophages into the central nervous system (CNS), gliosis, pallor of myelin sheaths, abnormalities of dendritic processes and neuronal loss.
Brain training is a program of regular activities purported to maintain or improve one's cognitive abilities. The phrase “cognitive ability” usually refers to components of fluid intelligence such as executive function and working memory. Cognitive training reflects a hypothesis that cognitive abilities can be maintained or improved by exercising the brain, analogous to the way physical fitness is improved by exercising the body. Cognitive training activities can take place in numerous modalities such as cardiovascular fitness training, playing online games or completing cognitive tasks in alignment with a training regimen, playing video games that require visuospatial reasoning, and engaging in novel activities such as dance, art, and music.
Cognitive impairment is an inclusive term to describe any characteristic that acts as a barrier to the cognition process or different areas of cognition. Cognition, also known as cognitive function, refers to the mental processes of how a person gains knowledge, uses existing knowledge, and understands things that are happening around them using their thoughts and senses. Cognitive impairment can be in different domains or aspects of a person's cognitive function including memory, attention span, planning, reasoning, decision-making, language, executive functioning, and visuospatial functioning. The term cognitive impairment covers many different diseases and conditions and may also be symptom or manifestation of a different underlying condition. Examples include impairments in overall intelligence, specific and restricted impairments in cognitive abilities, neuropsychological impairments, or it may describe drug-induced impairment in cognition and memory. Cognitive impairments may be short-term, progressive, or permanent.
The NINCDS-ADRDA Alzheimer's Criteria were proposed in 1984 by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association and are among the most used in the diagnosis of Alzheimer's disease (AD). These criteria require that the presence of cognitive impairment and a suspected dementia syndrome be confirmed by neuropsychological testing for a clinical diagnosis of possible or probable AD; while they need histopathologic confirmation for the definitive diagnosis. They specify as well eight cognitive domains that may be impaired in AD. These criteria have shown good reliability and validity.
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems with language, disorientation, mood swings, loss of motivation, self-neglect, and behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to twelve years.
The Montreal Cognitive Assessment (MoCA) is a widely used screening assessment for detecting cognitive impairment. It was created in 1996 by Ziad Nasreddine in Montreal, Quebec. It was validated in the setting of mild cognitive impairment (MCI), and has subsequently been adopted in numerous other clinical settings. This test consists of 30 points and takes 10 minutes for the individual to complete. The original English version is performed in seven steps, which may change in some countries dependent on education and culture. The basics of this test include short-term memory, executive function, attention, focus, and more.
Alzheimer's Disease Neuroimaging Initiative (ADNI) is a multisite study that aims to improve clinical trials for the prevention and treatment of Alzheimer's disease (AD). This cooperative study combines expertise and funding from the private and public sector to study subjects with AD, as well as those who may develop AD and controls with no signs of cognitive impairment. Researchers at 63 sites in the US and Canada track the progression of AD in the human brain with neuroimaging, biochemical, and genetic biological markers. This knowledge helps to find better clinical trials for the prevention and treatment of AD. ADNI has made a global impact, firstly by developing a set of standardized protocols to allow the comparison of results from multiple centers, and secondly by its data-sharing policy which makes available all at the data without embargo to qualified researchers worldwide. To date, over 1000 scientific publications have used ADNI data. A number of other initiatives related to AD and other diseases have been designed and implemented using ADNI as a model. ADNI has been running since 2004 and is currently funded until 2021.
Florbetaben, sold under the brand name Neuraceq, is a diagnostic radiotracer developed for routine clinical application to visualize β-amyloid plaques in the brain. It is a fluorine-18 (18F)-labeled stilbene derivative.
LATE is a term that describes a prevalent medical condition with impaired memory and thinking in advanced age, often culminating in the dementia clinical syndrome. In other words, the symptoms of LATE are similar to those of Alzheimer's disease.
The Cogstate Brief Battery (CBB) is a computer-based cognitive assessment used in clinical trials, healthcare, and academic research to measure neurological cognition. It was developed by Cogstate Ltd.
Alzheimer's disease (AD) in African Americans is becoming a rising topic of interest in AD care, support, and scientific research, as African Americans are disproportionately affected by AD. Recent research on AD has shown that there are clear disparities in the disease among racial groups, with higher prevalence and incidence in African Americans than the overall average. Pathologies for Alzheimer’s also seem to manifest differently in African Americans, including with neuroinflammation markers, cognitive decline, and biomarkers. Although there are genetic risk factors for Alzheimer’s, these account for few cases in all racial groups.
In patients with MCI, exercise training (6 months) is likely to improve cognitive measures and cognitive training may improve cognitive measures. ... Clinicians should recommend regular exercise (Level B). ... Recommendation: For patients diagnosed with MCI, clinicians should recommend regular exercise (twice/week) as part of an overall approach to management (Level B).