Concept Of Mild Cognitive Impairment Research Articles

Mild cognitive impairment: what's next?

The concept of mild cognitive impairment is one of the promising directions for studying the predementia stages of different diseases. The feasibility of studying this phenomenon is due not only to a high risk of dementia, but also the potential reversibility of cognitive decline in old age. Long-term follow-up of patients shows different trajectories of cognitive decline in aging. The study of risk factors for the progression of moderate cognitive impairment provided an opportunity to highlight new horizons of prevention of dementia of various etiologies. Despite the insufficient effectiveness of drug therapy in patients with moderate cognitive impairment, exploring the opportunities for possible treatment of their subtypes seems promising from the point of view of improving clinical symptoms and a possible reduction in the rate of disease progression.

Mild cognitive impairment in primary care: a clinical review

Dementia is projected to become a global health priority but often not diagnosed in its earlier preclinical stage which is mild cognitive impairment (MCI). MCI is generally referred as a...

The concept of mild cognitive impairment: a victim of its ubiquity.

Mild cognitive impairment (MCI) is a term used to describe individuals with cognitive impairment that is not severe enough to affect daily functioning (e.g. Petersen, 2004; Winblad et al., 2004). Although MCI has been used to describe cognitive abnormality due to any number of causes that can be progressive, stable, or reversible, it is most often considered to be a transition phase between normal cognition and dementia.

Mild cognitive impairment: A concept analysis.

To clarify the concept of mild cognitive impairment (MCI) and identify its attributes to enhance understanding of its implications for nursing practice and research. MCI is a concept that has evolved, thus clarification of this concept is essential for the advancement of nursing science. Walker and Avant's eight steps of concept analysis strategy was used. Manuals of mental disorders and databases such as PubMed, Springer, PsychINFO, Cumulative Index to Nursing and Allied Health Literature, and Education Resources Information Center (ERIC) from 1982 to 2018. A literature search was conducted using keywords such as "mild," "cognitive," "impairment," and "deterioration." The concept of MCI is defined as the transitional state between cognitive state normal for age and the early manifestation of dementia states. It is characterized by the presence of objective and subjective evidence of impairment in one or multiple cognitive domains, independence in daily activities, can be reversible, and is a risk factor for dementia. Clarification of MCI serves as a framework for identification, treatment, and interventions that may support healthy aging in older adults.

F66. Event-related potentials on working memory tasks for early diagnosis of Alzheimer’s disease and mild cognitive impairment

Alzheimer’s disease (AD) affects above 24 million people in the world. Petersen et al. developed the concept of mild cognitive impairment (MCI), thus describing a state of pre-dementia characterized by intermediate symptoms between normal aging and dementia caused by the onset of AD. Electroencephalographic (EEG) records in patients with AD/MCI evidence neuronal degeneration and functional/ cognitive impairment long before loss of brain tissue can be detected by structural neuroimaging methods, thus allowing an early diagnosis. A number of studies show that AD and MCI patients demonstrate abnormalities in EEG rhythms. Such alterations can be observed in both resting and task-related EEG protocols. In this study we conducted an Event-Related Potential (ERP) analysis from 32-channel EEG recorded when participants from three groups (healthy elderly, MCI and AD) performed a three-level N-back working memory (WM) task, with the purpose of finding out whether or not an early diagnosis of AD/MCI can be established based on such measures. A total of 61 participants were enrolled, of whom 15 had Alzheimer’s disease (AD), 20 had mild cognitive impairment (MCI) and 26 were healthy elderly (HE) individuals. Control group participants (HE) were recruited at Concordia University in Montreal, Canada. Patients (MCI and AD) were recruited at the Jewish General Hospital (JGH) Memory Clinic, a tertiary care referral center of McGill University. Ethical approval was obtained from the involved institutions and all participants provided written consent. All subjects were submitted to a three-level N-back task in ascending WM load (0-back, 1-back, 2-back). Each condition consisted of 100 trials, 40% of which were match trials. The stimuli (digits from 1 to 9) were presented during 600 ms with an inter-stimulus interval of 1400 ms. Participants responded by pressing the left or right button on a keyboard with the index finger of each hand. EEG signals were recorded at 500 Hz sampling rate using a 32-channel Neuroscan device. Of the 32 channels available, two were reserved to monitor horizontal and vertical eyeball movements, and a third one was attached to the right earlobe and used as an additional reference. ERPs of the 29-channel EEG for each of the six N-back tasks (match and non-match responses of the three-level WM load) were separately obtained and submitted to statistical analysis. The multiple comparison tests used were based on the Cluster correction. A considerable amount of significant differences between patient and control groups were found in the ERP during execution of the WM tasks, predominantly in fronto-centro-parietal electrodes. Our results indicate that, compared to the control group, both patient groups (MCI and AD) show a decrease in the amplitude of the P450 component, which is related to WM update. Although tests on larger databases are required to confirm these results, they are promising for achieving an early ERP-based diagnosis of MCI and AD.

Problems in Classifying Mild Cognitive Impairment (MCI): One or Multiple Syndromes?

As the conceptual, methodological, and technological advances applied to dementias have evolved the construct of mild cognitive impairment (MCI), one problem encountered has been its classification into subtypes. Here, we aim to revise the concept of MCI and its subtypes, addressing the problems of classification not only from the psychometric point of view or by using alternative methods, such as latent class analysis, but also considering the absence of normative data. In addition to the well-known influence of certain factors on cognitive function, such as educational level and cultural traits, recent studies highlight the relevance of other factors that may significantly affect the genesis and evolution of MCI: subjective memory complaints, loneliness, social isolation, etc. The present work will contemplate the most relevant attempts to clarify the issue of MCI categorization and classification, combining our own data with that from recent studies which suggest the role of relevant psychosocial factors in MCI.

Clinical Aspects of Alzheimer Disease

The clinical diagnosis of Alzheimer disease (AD) has been well established, but there is a widespread misunderstanding about the relationship between dementia (a syndrome) and AD (a cause of dementia). AD is the most common etiology that causes dementia in mid- and late life. The prototypical clinical presentation is that of a gradually worsening problem with learning new information, that is, a short-term memory deficit, accompanied by cognitive impairment in other domains, including language, spatial cognition, and executive functioning, as well as changes in personality and behavior. A key element of the diagnosis of dementia is that daily functioning is impaired. The concept of mild cognitive impairment (MCI) as the earliest symptomatic presentation of a dementing illness is now widely accepted. MCI due to AD typically presents with isolated problems with learning and memory without substantial loss of ability to function in daily life. Less common variants of AD are now recognized and include a disorder in which spatial and visual cognitive dysfunction occurs or in which word-finding problems predominate at the onset of symptoms. Although AD as a cause of dementia is the most common among etiologies, AD often co-occurs with other neurodegenerative diseases and with cerebrovascular disease. The presence of multietiology dementia in which AD is a contributor is particularly common in the eighth decade of life and beyond. Key words: Alzheimer disease, cognitive impairment, dementia, mild cognitive impairment

From mild cognitive impairment to subjective cognitive decline: conceptual and methodological evolution.

Identification of subjects at the early stages of Alzheimer’s disease (AD) is fundamental for drug development and possible intervention or prevention of cognitive decline. The concept of mild cognitive impairment (MCI) evolved during the past two decades to define subjects at the transitional stage between normal aging and dementia. Evidence from cross-sectional and longitudinal studies has shown that MCI is associated with an increased risk of positive AD biomarkers and an increased annual conversion rate of 5%–17% to AD. The presence of AD biomarkers in subjects with MCI was associated with an even higher risk of progression to dementia. However, earlier clinical trials for pharmacotherapy in subjects with MCI were disappointing. To extend the spectrum of AD to an earlier stage before MCI, subjective cognitive decline (SCD) was introduced and was defined as self-reported cognitive decline before the deficits could be detected by cognitive tests. Subjects with SCD have an increased risk of underlying AD pathology. However, SCD can also develop secondary to other heterogeneous etiologies, including other neurodegenerative and psychiatric diseases, personality traits, physical conditions, and medication use. Several clinical and biomarker features were proposed to predict risk of conversion to AD in subjects with SCD. Further longitudinal studies are needed to support the validity of these high-risk features.

Diagnosing Mild Cognitive Impairment as a Precursor to Dementia: Fact or Fallacy?

Mild cognitive impairment (MCI) describes a period of subclinical cognitive decline associated with an increased risk for the development of Alzheimer's disease (AD). However, research groups have rapidly moved from defining MCI as a risk profile for AD, to promoting MCI as a clinical diagnosis without sufficient evidence of its validity as a diagnostic entity. Specifically, the criterion, subjective change in cognition, remains controversial in light of growing evidence that subjective reports are inadequate predictors of genuine cognitive impairment. Further, operationalisation of the cognitive impairment criterion varies widely across studies in terms of which domains are assessed, and how these domains are assessed. Many studies also fail to acknowledge the psychometric limitations of neuropsychological measures and how this may impact the diagnosis of MCI. In addition, recent research indicates that MCI is longitudinally unstable, with up to 48% of those diagnosed with MCI “recovering” to age appropriate levels of functioning over time. While the MCI concept as it is currently defined may be useful in terms of indicating a risk profile, its ability to sensitively and specifically identify those who will transition to a clinical state remains questionable.

Early Dementia Screening.

As the population of the world increases, there will be larger numbers of people with dementia and an emerging need for prompt diagnosis and treatment. Early dementia screening is the process by which a patient who might be in the prodromal phases of a dementing illness is determined as having, or not having, the hallmarks of a neurodegenerative condition. The concepts of mild cognitive impairment, or mild neurocognitive disorder, are useful in analyzing the patient in the prodromal phase of a dementing disease; however, the transformation to dementia may be as low as 10% per annum. The search for early dementia requires a comprehensive clinical evaluation, cognitive assessment, determination of functional status, corroborative history and imaging (including MRI, FDG-PET and maybe amyloid PET), cerebrospinal fluid (CSF) examination assaying Aβ1–42, T-τ and P-τ might also be helpful. Primary care physicians are fundamental in the screening process and are vital in initiating specialist investigation and treatment. Early dementia screening is especially important in an age where there is a search for disease modifying therapies, where there is mounting evidence that treatment, if given early, might influence the natural history—hence the need for cost-effective screening measures for early dementia.

Are We Ready? The Construct of Subjective Cognitive Impairment and its Utilization in Clinical Practice: A Preliminary UK-Based Service Evaluation.

Extensive research on the concept of mild cognitive impairment (MCI) as a potential prodromal stage of dementia has highlighted the likelihood that abnormalities in information processing occur at even earlier stages in the disease process with research increasingly focused on the relatively new concept of subjective cognitive impairment (SCI). An individual with SCI will experience cognitive impairment solely on a subjective level, which is in contrast to an individual with MCI who will also experience cognitive impairment at an objective level. SCI is believed to be a risk factor for development of MCI. This qualitative service evaluation aimed to determine how much is known about SCI and how it is currently managed in specialist clinical practice in the UK. An email-based questionnaire containing a vignette of an individual presenting with SCI was distributed to 112 memory clinics requesting information on their most likely approach to such an individual. The 21% response rate evinces potential time pressure within clinical services that may preclude research participation and/or a lack of issue salience at present. However, the data from those who responded provide an important insight into 'where we are now' in relation to this issue. Analysis revealed main themes associated with SCI, namely the factors that influence what action is taken when an individual presents and what further investigations are performed, the multiplicity of potential outcomes experienced, and the barriers clinicians may face. The findings highlight the need for a coherent and consistent framework in relation to the management of SCI.

Mild Cognitive Impairment: At the Crossroad of Neurodegeneration and Vascular Dysfunction.

The concept of mild cognitive impairment (MCI) was first introduced for the purpose of identifying individuals in an intermediate state between no cognitive impairment and Alzheimer's disease (AD). Recently, the heterogeneity of MCI has attracted attention as it has become clear that other diseases, such as cerebrovascular disease and Parkinson disease can also cause mild cognitive deficits, prompting a redefinition of MCI. Heterogeneity of MCI has been confirmed by neuropathological examinations. Most MCI patients not only possess amyloid plaques and neurofibrillary tau tangles, but also cerebral vascular pathology such as arteriosclerosis and cerebral amyloid angiopathy (CAA). CAA induces cerebral infarcts or hemorrhage of varying size and type, attributing to further cognitive impairment. Sporadic AD and CAA has been suggested to be the consequence of Aβ elimination failure, mainly caused by disturbance of the perivascular drainage system. Since severe CAA is an independent risk factor for dementia, facilitation of Aβ clearance has been suggested as a potential treatment of AD and MCI. Many epidemiological studies have shown that vascular risk factors increase incidence of MCI and its progression to AD. Accordingly, control of such factors has been shown to reduce risk of conversion to AD and ameliorate cognitive impairment in AD patients. Neurovascular approaches may therefore hold promise for the treatment of dementia in an era of preventive neurology.

Mild Cognitive Impairment.

As individuals age, the quality of cognitive function becomes an increasingly important topic. The concept of mild cognitive impairment (MCI) has evolved over the past 2 decades to represent a state of cognitive function between that seen in normal aging and dementia. As such, it is important for health care providers to be aware of the condition and place it in the appropriate clinical context. Numerous international population-based studies have been conducted to document the frequency of MCI, estimating its prevalence to be between 15% and 20% in persons 60 years and older, making it a common condition encountered by clinicians. The annual rate in which MCI progresses to dementia varies between 8% and 15% per year, implying that it is an important condition to identify and treat. In those MCI cases destined to develop Alzheimer disease, biomarkers are emerging to help identify etiology and predict progression. However, not all MCI is due to Alzheimer disease, and identifying subtypes is important for possible treatment and counseling. If treatable causes are identified, the person with MCI might improve. MCI is an important clinical entity to identify, and while uncertainties persist, clinicians need to be aware of its diagnostic features to enable them to counsel patients. MCI remains an active area of research as numerous randomized controlled trials are being conducted to develop effective treatments.

Geriatric Psychiatry: What's in a Name, and Five Concerns about DSM-5.

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Mild cognitive impairment: diagnosis, longitudinal course, and emerging treatments.

Mild cognitive impairment (MCI) is widely regarded as the intermediate stage of cognitive impairment between the changes seen in normal cognitive aging and those associated with dementia. Elderly patients with MCI constitute a high-risk population for developing dementia, in particular Alzheimer's disease (AD). Although the core clinical criteria for MCI have remained largely unchanged, the operational definition of MCI has undergone several revisions over the course of the last decade and remains an evolving diagnosis. Prognostic implications of this diagnosis are becoming clearer with regard to the risk of progressive cognitive deterioration. Although patients with MCI may represent an optimal target population for pharmacological and non-pharmacological interventions, results from clinical trials have been mixed and an effective treatment remains elusive. This article provides a brief overview of the evolution of the concept of MCI and reviews current diagnostic criteria, the longitudinal course of the disorder, and current and emerging treatments for MCI.

The spectrum of cognitive impairment in Lewy body diseases.

Cognitive impairment represents an important and often defining component of the clinical syndromes of Lewy body disorders: Parkinson's disease and dementia with Lewy bodies. The spectrum of cognitive deficits in these Lewy body diseases encompasses a broad range of clinical features, severity of impairment, and timing of presentation. It is now recognized that cognitive dysfunction occurs not only in more advanced Parkinson's disease but also in early, untreated patients and even in those patients with pre-motor syndromes, such as rapid eye movement behavior disorder and hyposmia. In recent years, the concept of mild cognitive impairment as a transitional or pre-dementia state in Parkinson's disease has emerged. This has led to much research regarding the diagnosis, prognosis, and underlying neurobiology of mild cognitive impairment in Parkinson's disease, but has also raised questions regarding the usefulness of this concept and its application in clinical and research settings. In addition, the conundrum of whether Parkinson's disease dementia and dementia with Lewy bodies represent the same or different entities remains unresolved. Although these disorders overlap in many aspects of their presentations and pathophysiology, they differ in other elements, such as timing of cognitive, behavioral, and motor symptoms; medication responses; and neuropathological contributions. This article examines the spectrum and evolution of cognitive impairment in Lewy body disorders and debates these controversial issues in the field using point-counterpoint approaches.

Prognosis of Mild Cognitive Impairment in General Practice: Results of the German AgeCoDe Study

The concept of mild cognitive impairment (MCI) has recently been introduced into the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as mild neurocognitive disorder, making it a formal diagnosis. We investigated the prognostic value of such a diagnosis and analyzed the determinants of the future course of MCI in the AgeCoDe study (German Study on Ageing, Cognition, and Dementia in Primary Care Patients). We recruited 357 patients with MCI aged 75 years or older from primary care practices and conducted follow-up with interviews for 3 years. Depending on the course of impairment over time, the patients were retrospectively split into 4 groups representing remittent, fluctuating, stable, and progressive courses of MCI. We performed ordinal logistic regression analysis and classification and regression tree (CART) analysis. Overall, 41.5% of the patients had remission of symptoms with normal cognitive function 1.5 and 3 years later, 21.3% showed a fluctuating course, 14.8% had stable symptoms, and 22.4% had progression to dementia. Patients were at higher risk for advancing from one course to the next along this spectrum if they had symptoms of depression, impairment in more than 1 cognitive domain, or more severe cognitive impairment, or were older. The result on a test of the ability to learn and reproduce new material 10 minutes later was the best indicator at baseline for differentiating between remittent and progressive MCI. Symptoms of depression modified the prognosis. In primary care, about one-quarter of patients with MCI have progression to dementia within the next 3 years. Assessments of memory function and depressive symptoms are helpful in predicting a progressive vs a remittent course. When transferring the concept of MCI into clinical diagnostic algorithms (eg, DSM-5), however, we should not forget that three-quarters of patients with MCI stayed cognitively stable or even improved within 3 years. They should not be alarmed unnecessarily by receiving such a diagnosis.

The unbearable lightness of MCI

The title of this Editorial, with apologies to Milan Kundera (Kundera, 1985) implies no lack of gravitas in the concept of Mild Cognitive Impairment (MCI). Rather, it refers to the current definitions of MCI being somewhat free-floating, loosely anchored to diagnostic frameworks, and more conceptual than operational. In their defense, we cannot completely obliterate the flexibility clinicians need in order to exercise expert judgment and take individual patients’ circumstances into account when making clinical diagnoses. Further, it would be imprudent to prematurely codify diagnostic criteria for MCI; after all, we are still gathering basic information about the wide range of mildly impaired states that we encounter in different clinical settings and in the population at large.

Cognitive impairment 3 years after neurological Varicella-zoster virus infection: a long-term case control study

Varicella-zoster virus (VZV) is one of the most common viruses causing central nervous system (CNS) infection, sometimes with severe neurological complications and sequelae despite appropriate antiviral treatment. Whether the neurological sequelae of VZV CNS infections include long-term cognitive impairment and how this impairment might affect the patients is still largely unknown. In this study, 14 patients with predominant CNS manifestations caused by VZV infection underwent cognitive testing 3 years (median 39.5 months, range 31-52 months) after acute disease. The results were compared with those for 28 controls, matched for age and gender. The tests covered the cognitive domains of speed and attention, memory and learning, visuospatial function, language and executive function. To further assess the cognitive dysfunction caused by neurological VZV infection, patients were classified into the concept of mild cognitive impairment (MCI), which is associated with development of dementia in other pathologies. The VZV patients performed significantly worse than controls on four tests covering the domains of speed and attention, memory and learning and executive function. The cut-off was set at 1.5 SD below mean age. In addition, a greater proportion of VZV patients were classified with MCI as compared with controls. In conclusion, patients with previous VZV infection affecting the brain had signs of long-term cognitive impairment in the domains of speed and attention, memory and learning and executive function. However, larger study populations are needed to confirm these results.

Mild cognitive impairment in Parkinson's disease

The concept of mild cognitive impairment (MCI) in the general population has received increased attention over recent years, and is associated with risk of progression to Alzheimer's disease. Within Parkinson's disease (PD), MCI (PD-MCI) is also now recognised to be relatively common, with certain subtypes predicting progression to Parkinson's disease dementia (PDD). Recently, criteria to better characterise PD-MCI and its subtypes have been produced by the Movement Disorder Society. In contrast to the population as a whole, where amnestic MCI is the most common subtype, non-amnestic PD-MCI dominates, with prominent executive and attention dysfunction. Although the pathophysiology of PD-MCI is poorly understood and encompasses both PD and non-PD pathology, it is most likely the result of a complex interaction between neurotransmitter dysfunction, synaptic pathology, protein aggregation and neuronal damage. Determining the factors that influence the progression of these pathologies in PD and the individuals at risk of ultimately developing PDD is critical for targeted intervention and drug discovery studies. Further work is required, however, to determine the significance of PD-MCI and also to validate the diagnostic criteria. This would be best delivered in the form of longitudinal studies in homogenous cohorts of PD participants, to allow prognostication and generalisation among the PD population. At the present time, no drug therapies are available for PD-MCI. Management includes screening for the disorder, excluding treatable causes of cognitive decline and cautious use of dopamine agonists and medications such as anticholinergics.