Cognitive impairment | |
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Other names | Cognitive deficit |
Specialty | Psychiatry |
Cognitive impairment is an inclusive term to describe any characteristic that acts as a barrier to the cognition process or different areas of cognition. [1] 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. [2] Cognitive impairment can be in different domains or aspects of a person's cognitive function including memory, attention span, planning, reasoning, decision-making, language (comprehension, writing, speech), 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 (as with intellectual disabilities), specific and restricted impairments in cognitive abilities (such as in learning disorders like dyslexia), neuropsychological impairments (such as in attention, working memory or executive function), or it may describe drug-induced impairment in cognition and memory (such as that seen with alcohol, glucocorticoids, [3] and the benzodiazepines. [4] ). Cognitive impairments may be short-term, progressive (gets worse over time), or permanent. [2]
There are different approaches to assessing or diagnosing a cognitive impairment including neuropsychological testing using various different tests that consider the different domains of cognition. Examples of shorter assessment clinical tools include the Mini Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). [5] There are many different syndromes and pathologies that cause cognitive impairment including dementia, mild neurocognitive disorder, and Alzheimer's disease. [5]
Cognitive impairments may be caused by many different factors including environmental factors or injuries to the brain (e.g. traumatic brain injury), neurological illnesses, or mental disorders. [2] While more common in elderly people, not all people who are elderly have cognitive impairments. [2] Some known causes of cognitive impairments that are more common in younger people are: chromosomal abnormalities or genetic syndromes, exposure to teratogens while in utero (e.g., prenatal exposure to drugs), undernourishment, poisonings, autism, and child abuse. [2] Stroke, dementia, depression, schizophrenia, substance abuse, brain tumours, malnutrition, brain injuries, hormonal disorders, and other chronic disorders may result in cognitive impairment with aging. Cognitive impairment may also be caused by a pathology in the brain. Examples include Alzheimer's disease, Parkinson's disease, HIV/AIDS-induced dementia, dementia with Lewy bodies, and Huntington’s disease. [2]
Short-term cognitive impairment can be caused by pharmaceutical drugs such as sedatives. [2]
Screening for cognitive impairment in those over the age of 65 without symptoms is of unclear benefit versus harm as of 2020. [6] In a large population-based cohort study included 579,710 66-year-old adults who were followed for a total of 3,870,293 person-years (average 6.68 ± 1.33 years per person), subjective cognitive decline was significantly associated with an increased risk of subsequent dementia. [7]
In addition to a series of cognitive tests, general practitioner physicians often also rely on clinical judgement for diagnosing cognitive impairment. [8] Clinical judgement is ideal when paired with additional tests to that permit the medical professional to confirm the diagnosis or confirm the absence of a diagnosis. [8] Clinical judgement in these cases may also help inform the choice in additional tests. [8]
Deciding on an appropriate treatment for people with cognitive decline takes clinical judgement based on the diagnosis (the specific cognitive problem), the person's symptoms, other patient factors including expectations and the person's own ideas, and previous approaches to helping the person. [8]
Although one would expect cognitive decline to have major effects on job performance, it seems that there is little to no correlation of health with job performance. With the exception of cognitive-dependent jobs such as air-traffic controller, professional athlete, or other elite jobs, age does not seem to impact one's job performance. This obviously conflicts with cognitive tests given, so the matter has been researched further. One possible reason for this conclusion is the rare need for a person to perform at their maximum. There is a difference between typical functioning, that is – the normal level of functioning for daily life, and maximal functioning, that is – what cognitive tests observe as our maximum level of functioning. As the maximum cognitive ability that we are able to achieve decreases, it may not actually affect our daily lives, which only require the normal level. [9]
Some studies have indicated that childhood hunger might have a protective effect on cognitive decline. One possible explanation is that the onset of age-related changes in the body can be delayed by calorie restriction. Another possible explanation is the selective survival effect, as the study participants who had a childhood with hunger tend to be the healthiest of their era. [10]
When a person's level of cognition declines, it is often harder to live in an independent setting. Some people may have trouble taking care of themselves and the burden on the people caring for them can increase. Some people require supportive healthcare and, in some cases, institutionalization. [5]
The role of light therapy for treating people with cognitive impairment or dementia is not fully understood. [11] [12] [13] [14]
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.
Neuropsychological tests are specifically designed tasks that are used to measure a psychological function known to be linked to a particular brain structure or pathway. Tests are used for research into brain function and in a clinical setting for the diagnosis of deficits. They usually involve the systematic administration of clearly defined procedures in a formal environment. Neuropsychological tests are typically administered to a single person working with an examiner in a quiet office environment, free from distractions. As such, it can be argued that neuropsychological tests at times offer an estimate of a person's peak level of cognitive performance. Neuropsychological tests are a core component of the process of conducting neuropsychological assessment, along with personal, interpersonal and contextual factors.
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.
In neuropathy, primary progressive aphasia (PPA) is a type of neurological syndrome in which language capabilities slowly and progressively become impaired. As with other types of aphasia, the symptoms that accompany PPA depend on what parts of the brain's left hemisphere are significantly damaged. However, unlike most other aphasias, PPA results from continuous deterioration in brain tissue, which leads to early symptoms being far less detrimental than later symptoms.
Cognitive reserve is the mind's and brain's resistance to damage of the brain. The mind's resilience is evaluated behaviorally, whereas the neuropathological damage is evaluated histologically, although damage may be estimated using blood-based markers and imaging methods. There are two models that can be used when exploring the concept of "reserve": brain reserve and cognitive reserve. These terms, albeit often used interchangeably in the literature, provide a useful way of discussing the models. Using a computer analogy, brain reserve can be seen as hardware and cognitive reserve as software. All these factors are currently believed to contribute to global reserve. Cognitive reserve is commonly used to refer to both brain and cognitive reserves in the literature.
A cognitive intervention is a form of psychological intervention, a technique and therapy practised in counselling. It describes a myriad of approaches to therapy that focus on addressing psychological distress at a cognitive level. It is also associated with cognitive therapy, which focuses on the thought process and the manner by which emotions have bearing on the cognitive processes and structures. The cognitive intervention forces behavioral change. Counselors adopt different technique level to suit the characteristic of the client. For instance, when counseling adolescents, a more advanced strategy is adopted than the intervention used in children. Before the intervention, an initial cognitive assessment is also conducted to cover the concerns of the cognitive approach, which cover the whole range of human expression - thought, feeling, behavior, and environmental triggers.
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.
Alcohol-related dementia (ARD) is a form of dementia caused by long-term, excessive consumption of alcohol, resulting in neurological damage and impaired cognitive function.
Mild cognitive impairment (MCI) is a neurocognitive disorder which involves cognitive impairments beyond those expected based on an individual's age and education but which are not significant enough to interfere with instrumental activities of daily living. MCI may occur as a transitional stage between normal aging and dementia, especially Alzheimer's disease. It includes both memory and non-memory impairments. The cause of the disorder remains unclear, as well as both its prevention and treatment, with some 50 percent of people diagnosed with it going on to develop Alzheimer's disease within five years. The diagnosis can also serve as an early indicator for other types of dementia, although MCI may remain stable or even remit.
Pseudodementia is a condition that leads to cognitive and functional impairment imitating dementia that is secondary to psychiatric disorders, especially depression. Pseudodementia can develop in a wide range of neuropsychiatric disease such as depression, schizophrenia and other psychosis, mania, dissociative disorders, and conversion disorders. The presentations of pseudodementia may mimic organic dementia, but are essentially reversible on treatment and doesn't lead to actual brain degeneration. However, it has been found that some of the cognitive symptoms associated with pseudodementia can persist as residual symptoms and even transform into true neurodegenerative dementia in some cases.
Psychological therapies for dementia are starting to gain some momentum. Improved clinical assessment in early stages of Alzheimer's disease and other forms of dementia, increased cognitive stimulation of the elderly, and the prescription of drugs to slow cognitive decline have resulted in increased detection in the early stages. Although the opinions of the medical community are still apprehensive to support cognitive therapies in dementia patients, recent international studies have started to create optimism.
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens, and 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.
The Addenbrooke's Cognitive Examination (ACE) and its subsequent versions are neuropsychological tests used to identify cognitive impairment in conditions such as dementia.
Geriatric psychology is a subfield of psychology that specializes in the mental and physical health of individuals in the later stages of life. These specialized psychologists study a variety of psychological abilities that deplete as aging occurs such as memory, learning capabilities, and coordination. Geriatric psychologists work with elderly clients to conduct the diagnosis, study, and treatment of certain mental illnesses in a variety of workplace settings. Common areas of practice include loneliness in old age, depression, dementia, Alzheimer's disease, vascular dementia, and Parkinson's disease.