Mild cognitive impairment (MCI): concept, causes and symptoms

through Mild cognitive impairment (MCI)By consensus, it is understood that a transitional phase between normal aging and dementia characterized by an objective loss of cognitive function, demonstrated in a neuropsychological assessment and by the patient.

Signs and symptoms of mild cognitive impairment

At the subjective level, is accompanied by complaints about loss of cognitive abilities. In addition, for mild cognitive disorders, these cognitive deficits must not interfere with the patient’s autonomy and must not be able to be linked to other pathologies such as psychiatric and neurological disorders, addictions, etc. Therefore, the main difference from a patient with dementia is the maintenance of independence in activities of daily living, despite some degree of cognitive impairment.

The first diagnostic criteria for DCL were described by Petersen et al (1999), although the concept was born much earlier. By doing a search on Pubmed, we can see that in 1990 we have already found manuscripts in which there is talk of mild cognitive impairment. initially, DCL was only considered as a diagnosis leading the subject to Alzheimer’s disease; however, in 2003 a team of experts (including Petersen himself) proposed to classify the diagnosis of DCL according to the cognitive domains affected in the neuropsychological assessment. Later, in a review by Gauthier et al. which took place in 2006, it was first proposed that different types of mild cognitive impairment can lead to different types of dementia.

Today, DCL is considered to be a condition that can lead to a certain type of dementia or simply not progressing.

Clinical characterization of mild cognitive impairment

To be realistic, a clear, unique and well-established diagnosis of mild cognitive impairment is not yet available.

Different authors apply different criteria to diagnose, and there is no total consensus on how to identify it. However, the first steps were taken to generate agreement and in the DSM-V manual we can already find a diagnosis of “mild neurocognitive disorder”, which bears some resemblance to DCL. Due to the lack of consensus, we will briefly cite the two bases on which the diagnosis of DCL rests.

1. Neuropsychological assessment

Neuropsychological assessment has become an indispensable tool in the diagnosis of dementias and also of mild cognitive impairment. For the diagnosis of DCL a comprehensive neuropsychological battery must be set up to assess the main cognitive domains (Memory, language, visuospatial reasoning, executive functions, psychomotor capacity and processing speed).

The assessment should show that at least one neuropsychological area is affected. However, there is currently no cut-off point for considering a cognitive domain as affected. In the case of dementia, it is usually established as a threshold of 2 negative standard deviations (or what is the same, that the performance is less than 98% of the population of the age group and the level of education of the patient ). In the case of DCL, there is no consensus for the cutoff, with the authors setting it at 1 negative standard deviation (16th percentile) and others at 1.5 negative standard deviation (7th percentile).

Based on the results obtained during the neuropsychological assessment, the type of mild cognitive impairment with which the patient is diagnosed is defined. Depending on the areas concerned, the following categories are established:

  • Single domain amnesic DCL: Only memory is affected.

  • Multi-domain amnesic DCL: Memory is affected and at least one other area.

  • Single domain non-amnesic DCL: Memory is preserved but some areas are affected.

  • Multi-domain non-amnesic DCL: Memory is preserved but several areas are affected.

These types of diagnoses can be found in the review by Winblad et al. (2004) and are one of the most widely used in research and clinical practice. Today, many longitudinal studies attempt to follow the evolution of different subtypes of DCL towards dementia. In this way, through neuropsychological evaluation, a patient prognosis could be made to achieve specific therapeutic actions.

There is currently no consensus and research has yet to offer a clear idea to confirm this fact, but some studies have reported that Single-domain or multiple-domain amnesic-type DCL would most likely lead to Alzheimer’s dementiaWhile in the case of patients progressing to vascular dementia, the neuropsychological profile could be much more varied and there may or may not be memory impairment. This would be due to the fact that in this case the cognitive disorders would be associated with lesions or microlesions (cortical or subcortical) which can lead to different clinical consequences.

2. Assessment of the patient’s degree of independence and other variables

One of the essential criteria for the diagnosis of mild cognitive impairment, which is shared by almost all of the scientific community, is that the patient must maintain his independence. If the activities of daily living are affected, it will make us suspect dementia (which would not confirm anything either). For this, and especially since the neuropsychological evaluation thresholds are not clear, the patient’s medical history will be essential. In order to assess these aspects, I recommend below various tests and scales widely used in clinical and research:

IDDD (Interview for Deterioration in Daily Living Activities in Dementia): assesses the degree of independence in activities of daily living.

EQ50: assesses the degree of quality of life of the patient.

3. Presence or absence of complaints

Another aspect considered necessary for the diagnosis of mild cognitive impairment is the presence of subjective cognitive complaints. Patients with DCL often report different types of cognitive impairment during the consultation, which are not only related to memory, but also to anomie (difficulty finding the names of things), disorientation, problems with concentration. , etc. Consideration of these complaints as part of the diagnosis is essential, but it should also be borne in mind that in many cases patients suffer from anosognosia, i.e. they are not aware of their deficits.

In addition, some authors argue that subjective complaints have more to do with mood than the actual cognitive state of the subject, and therefore we cannot leave everything in the hands of the profile of subjective complaints, even if they should not. be ignored. It is often very useful to compare the patient’s version with that of a loved one when in doubt.

4. Eliminate underlying neurological or psychiatric problems

Finally, when examining the medical history, it must be excluded that poor cognitive performance is the cause of other neurological or psychiatric problems (schizophrenia, bipolar disorder, etc.). It is also necessary to assess the degree of anxiety and mood. If we adopted strict diagnostic criteria, the presence of depression or anxiety would exclude the diagnosis of DCL.

However, some authors advocate the coexistence of a mild cognitive impairment with this type of symptomatology and propose diagnostic categories in terms of possible DCL (when there is a factor that makes the diagnosis of DCL doubtful) and probable DCL (when it is possible). there are no concurrent factors) in DCL), similar to how it is performed in other disorders.

A final reflection

Today, mild cognitive impairment is one of the main focuses of scientific research in the study of dementias. Why was he going to study? As we know it, medical, pharmacological and social advances have led to an increase in the expectation of life.

This added to a decrease in the birth rate which resulted in an older population. Dementias proved to be an unachievable imperative for many people who saw that as they grew older they maintained good physical health but suffered from memory loss that condemned them to a situation of addiction. Pathologies Neurodegenerative diseases are chronic and irreversible.

From a preventive approach, mild cognitive impairment opens up a therapeutic window in the treatment of the precipitous evolution towards dementia by pharmacological and non-pharmacological approaches. We cannot cure dementia, but DCL is a condition in which the individual, although cognitively impaired, retains full independence. If we can at least slow the progression to dementia, we will positively influence the quality of life for many people.

Bibliographical references:

  • Espinosa A, Alegret M, Valero S, Vinyes-Junqué G, Hernández I, Mauleón A, Rosende-Roca M, Ruiz A, López O, Tárraga L, Boada M. (2013) Longitudinal follow-up of 550 patients with mild cognitive impairment : evidence of an important conversion towards detection of dementia rates of the main risk factors involved. J Alzheimers Dis 34: 769-780

  • Gauthier S, Reisberg B, Zaudig M, Petersen RC, Ritchie K, Broich K, Belleville S, Brodaty H, Bennett D, Chertkow H, Cummings JL, de Leon M, Feldman H, Ganguli M, Hampel H, Scheltens P, Tierney MC, Whitehouse P, Winblad B. (2006) Mild cognitive impairment. Lancet 367: 1262-70.

  • Gorelick PB et al. (2011) Vascular Contributions to Cognitive Impairment and Dementia: A Statement for Health Care Professionals from the American Heart Association / American Stroke Association. Trace 42: 2672-713.

  • Janoutová J, Šerý O, Hosák L, Janout V. (2015) Is mild cognitive impairment a precursor of Alzheimer’s disease? Short summary. Cent Eur J Public Health 23: 365-7

  • Knopman DS and Petersen RC (2014) Mild Cognitive Impairment and Mild Dementia: A Clinical Perspective. Mayo Clin Proc 89: 1452-9.

  • Winblad B et al. (2004) Mild Cognitive Impairment Beyond Controversy Towards Consensus: Report of the International Mild Cognitive Impairment Working Group. J Intern Med 256: 240-46.

  • Petersen RC, Smith GE, Waring SC, Ivnik RJ, Tangalos EG, Kokmen E. (1999) Mild cognitive impairment: clinical characterization and outcome. Arch Neurol 56: 303-8.

  • Ryu SY, Lee SB, Kim TW, Lee TJ. (2015) Complaints of subjective memory, depressive symptoms, and instrumental activities of daily living in mild cognitive impairment. Int Psychogeriatr 11: 1-8.

Leave a Comment