Mild Cognitive Impairment (MCI): Concept, Causes And Symptoms
By Mild Cognitive Impairment (MCI) According to consensus, we understand that transitional phase between normal aging and dementia characterized by an objective loss of cognitive functions, demonstrated in a neuropsychological evaluation and, by the patient.
On a subjective level, is accompanied by complaints referring to loss of cognitive abilities. Furthermore, for it to be Mild Cognitive Impairment, these cognitive deficits must not interfere with the patient’s independence and must not be able to be related to other pathologies such as psychiatric and neurological disorders, addictions, etc. Therefore, the main difference compared to a patient with dementia is the maintenance of independence in activities of daily living, despite a certain degree of cognitive impairment.
The first diagnostic criteria for MCI were described by Petersen et al (1999), although the concept was born much earlier. Doing a search in Pubmed we can see that in 1990 we already found manuscripts that talk about Mild Cognitive Impairment. Initially, MCI was only seen as a diagnosis that led the subject to Alzheimer’s disease ; However, in 2003 a team of experts (including Petersen himself) proposed classifying the diagnosis of MCI based on the cognitive domains affected in the neuropsychological evaluation. 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.
Nowadays, MCI is seen as a condition that can lead the subject to some type of dementia or, simply, it may not evolve.
Clinical Characterization of Mild Cognitive Impairment
Being realistic, There is still no clear, single and well-established diagnosis for Mild Cognitive Deficit.
Different authors apply different criteria to diagnose it, and there is no total consensus about how to identify it. Even so, the first steps have been taken to generate an agreement and in the DSM-V manual we can already find a diagnosis of “Mild Neurocogntive Disorder”, which has a certain resemblance to MCI. Due to the lack of consensus, we are going to briefly mention the two bases on which the diagnosis of MCI is based.
Neuropsychological evaluation has become an indispensable tool in the diagnosis of dementia and also Mild Cognitive Impairment. For the diagnosis of MCI An exhaustive neuropsychological battery must be applied that allows us to evaluate the main cognitive domains (memory, language, visuospatial reasoning, executive functions, psychomotor capacity and processing speed).
Through the evaluation it must be demonstrated that, at least, there is one neuropsychological domain that is affected. Even so, there is currently no established cut-off point to consider a cognitive domain as affected. In the case of Dementia, the cut-off point is usually set at 2 negative standard deviations (or in other words, performance is below 98% of the population of the patient’s age group and educational level). In the case of MCI, there is no consensus for the cut-off point, with some authors establishing it at 1 negative standard deviation (16th percentile) and others at 1.5 negative standard deviations (7th percentile).
Based on the results obtained in the neuropsychological evaluation, the type of Mild Cognitive Impairment with which the patient is diagnosed is defined. Depending on the domains that are affected, the following categories are established:
These diagnostic types can be found in the review by Winblad et al. (2004) and are some of the most used in research and clinical practice. Nowadays, many longitudinal studies attempt to follow the evolution of the different subtypes of MCI towards dementia. In this way, through neuropsychological evaluation, a patient prognosis could be made to carry out specific therapeutic actions.
Currently there is no consensus and research has not yet offered a clear idea to confirm this fact, but, even so, some studies have reported that single-domain or multi-domain amnestic type MCI would be the most likely to lead to Alzheimer’s dementia while in the case of patients who progress towards vascular dementia, the neuropsychological profile could be much more varied and there may or may not be memory impairment. This would be because in this case the cognitive impairment would be associated with lesions or microlesions (cortical or subcortical) that could lead to different clinical consequences.
2. Evaluation 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 the entire 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 even more so when the cut-off points of the neuropsychological evaluation are not clear, the anamnesis of the patient’s clinical history will be essential. In order to evaluate these aspects, I recommend below different tests and scales that are widely used in clinical and research:
IDDD (Interview for Deterioration in Daily Living Activities in Dementia): Evaluates the degree of independence in activities of daily living.
EQ50: Evaluates the degree of quality of life of the patient.
3. Presence or absence of complaints
Another aspect that is considered necessary for the diagnosis of Mild Cognitive Impairment is the presence of subjective cognitive complaints. Patients with MCI usually report different types of cognitive complaints in the consultation, which are not only related to memory, but also to anomia (difficulty finding the names of things), disorientation, concentration problems, etc. Considering these complaints as part of the diagnosis is essential, although it should also be taken into account that in many cases patients suffer from anosognosia, that is, they are not aware of their deficits.
Furthermore, some authors maintain that subjective complaints have more to do with the mood than with the actual cognitive state of the subject and, therefore, we cannot leave everything in the hands of the profile of subjective complaints, although they should not be ignored. It is usually very useful to contrast the patient’s version with that of a family member in cases of doubt.
4. Rule out underlying neurological or psychiatric problems
Finally, when reviewing the medical history, it must be ruled out that poor cognitive performance is the cause of other neurological or psychiatric problems (schizophrenia, bipolar disorder, etc.). It is also necessary to carry out an evaluation of the degree of anxiety and mood. If we adopted strict diagnostic criteria, the presence of depression or anxiety would rule out the diagnosis of MCI.
However, some authors defend the coexistence of Mild Cognitive Impairment with this type of symptomatology and propose diagnostic categories in terms of possible MCI (when there are factors that make the diagnosis of MCI doubtful) and probable MCI (when there are no concomitant factors to MCI). ), in a similar way to how it is done in other disorders.
A final thought
Today, Mild Cognitive Impairment is one of the main focuses of scientific research in the context of the study of dementia. Why would it be studied? As we know, Medical, pharmacological and social advances have led to an increase in life expectancy.
This has been added to a decrease in the birth rate that has resulted in an older population. Dementias have become an unavoidable imperative for many people who have seen that as they aged they maintained a good level of physical health but suffered memory loss that condemned them to a situation of dependency. Neurodegenerative pathologies are chronic and irreversible.
From a preventive approach, Mild Cognitive Impairment opens a therapeutic window for the treatment of precipitated evolution towards dementia through pharmacological and non-pharmacological approaches. We cannot cure dementia, but MCI is a state in which the individual, although cognitively impaired, retains full independence. If we can at least slow the progression towards dementia, we will be positively influencing the quality of life of many individuals.
