The mild cognitive impairment (MCI) is a syndrome may have cognitive deficits beyond what is considered normal, which may or may not interfere with daily life and does not meet the criteria for dementia.
That is to say: the MCI, as the name suggests, is a type of cognitive impairment characterized by being mild (deficits are unimportant), but they are notorious enough not to be explained by the normal aging of the brain.
And is that people, as we get older, we lose our mental faculties.
We lose speed of thought, every time we are less agile mentally, our learning ability decreases, it can cost us more to remember things …
However, this slight cognitive decline is not considered any type of disease, and is classified as “cognitive deterioration associated with age” (DECAE).
The DECAE is considered a relatively benign phenomenon, and practically all people present it (to a greater or lesser degree) as we get older. Nobody gets rid of losing faculties with age.
However, the DCL does not refer to this benign aging of the human brain, but is considered a type of deterioration greater than that which is present in a DECAE.
Therefore, the DCL would constitute those types of cognitive declines that are not purely associated with age and therefore are not considered as “normal” but as pathological.
Usually when we talk about pathological cognitive deterioration, we are usually talking about dementia, such as Alzheimer’s dementia or dementia due
to Parkinson’s disease.
Mild Cognitive Impairment
However, MCI is not a dementia, it is a type of cognitive impairment lower than that presented in any type of dementia syndrome.
Thus, mild cognitive impairment refers to those people who are neither cognitively normal (have a greater deterioration than what should be expected by age) or dementia (have a lower deterioration than those with people with Dementia).
In fact, the term DCL was coined by Peterson in 1999 to refer to those unimportant cognitive disorders, with the aim of achieving an early diagnosis of Dementia.
This author argued that the criteria for diagnosing demential syndromes (especially Alzheimer’s disease ) were too strict, and only allowed detection of dementias when they had existed for a long time.
Put another way: for Peterson when a person had the deficits needed to diagnose Alzheimer’s dementia, it had been manifesting at a lower intensity for a long time.
In this way, Petersen considered DCL as a degenerative process that sooner or later would turn into Dementia.
However, it has been shown that not all people with mild cognitive impairment end up suffering from a dementing syndrome.
More specifically, taking into account the data provided by Iñiguez in 2006, only between 10% and 15% of patients with MCI end up developing a dementing syndrome.
Thus, by way of summary, the MCI is a type of deterioration greater than that considered “normal” but less than that related to demential syndromes.
In addition, this disease increases the likelihood of ending up suffering from a demential syndrome of 1-2% (for healthy people) up to 10-15% (for people with MCI).
Subtypes of mild cognitive impairment
Although the deficits of MCI are mild, the presentation of this disorder can vary and the type of cognitive decline can be of several forms.
Thus, at present 4 subtypes of mild cognitive impairment have been described, each with certain characteristics. Let’s review them quickly.
1. Single domain amnesiac DCL
A patient whose only cognitive complaint is related to a memory deficit would be labeled in this subtype.
It is the most frequent subtype and is characterized because the person does not present any type of cognitive deficit beyond a slight loss of memory.
For certain authors, this subtype of MCI could be considered as a stage prior to Alzheimer’s disease.
2. Amnesic DCL with involvement in multiple areas
A patient with memory loss and complaints in other cognitive areas such as problem solving, word naming or attention and concentration difficulties would be framed in this subtype.
There may be multiple cognitive deficits but all of them of low intensity, so it could not be considered a dementing syndrome.
3. Non-amnestic DCL with involvement in multiple areas
A patient without any alteration in his memory but with difficulties in other cognitive areas such as attention, concentration, language, calculation or problem solving would be diagnosed with non-amnestic MCI with affectations in multiple areas.
In this subtype, as in the previous one, multiple low intensity cognitive deficits can be presented, but with the difference that there is no memory loss.
4. DCL non-amnesic single domain
Finally, a patient who, as in the previous case, does not present a memory loss and only presents one of the other cognitive deficits described above , would be included in this subtype of MCI.
The diagnosis of cognitive deterioration Leve is usually complex since there are no precise and universally established criteria to detect this disorder.
The main requirement for the diagnosis is to present a cognitive deterioration evident by neuropsychological exploration ( mental performance tests ) without these meet the criteria of dementia.
Although there are no stable diagnostic criteria to detect mild cognitive impairment, I will comment below on those proposed by the International Psychogeriatric Association, which in my opinion clarify several concepts:
Decrease in cognitive ability at any age.
Decrease in cognitive capacity affirmed by the patient or informant.
Gradual decrease of minimum duration of six months.
Any of the following areas may be affected.
Memory and Learning
Attention and Concentration
Decrease in mental state assessment scores or neuropsychological tests.
This situation can not be explained by the presence of a Dementia or other medical cause.
Thus, the criteria to establish the diagnosis of MCI are to present complaints of declining cognitive abilities, which are detectable through mental performance tests and that are less severe than those of Dementia.
That is why, to be able to differentiate mild cognitive deterioration from a dementia takes on special importance, let’s see how we can do it.
Main differences with dementia
In order to clarify the differences between DCL and dementia, first we will see what are the diagnostic criteria of the edema syndrome .
According to the Diagnostic and Statistical Manual of Mental Disorder (DSM-IV), they are the following:
A. The presence of multiple cognitive deficits manifested by:
1. Impairment of memory (impairment of the ability to learn new information or recall information previously learned).
2. One (or more) of the following cognitive alterations:
(a) aphasia (language alteration)
(b) apraxia (impaired ability to perform motor activities, even though motor function is intact).
(c) agnosia (failure to recognize or identify objects, even though the sensory function is intact).
(d) alteration of the execution (eg, planning, organization, sequencing and abstraction.
B. Cognitive deficits in each of the A1 and A2 criteria cause a significant cognitive deterioration of work or social activity and represent a significant reduction in the previous level of activity.
C. Deficits are not due to other medical or psychiatric illnesses.
As we can see, the demential syndromes are characterized by the deterioration of memory and other cognitive alterations such as language, planning, problem solving, apraxia or agnosias.
The characteristics of MCI are practically the same as those of dementia, since in mild cognitive impairment we can see both memory deficits and the other cognitive deficits that we have just commented.
Therefore, the DCL can not be differentiated from dementia by the type of alterations that the person presents since they are the same in both pathologies, therefore, the differentiation can only be done through the severity of these.
In this way, the keys to differentiate DCL from dementia are the following:
Unlike dementia, the deterioration that occurs in MCI does not usually modify in excess the functionality of the person, which can continue to perform activities autonomously and without difficulties (except tasks that require a very high cognitive performance).
In dementias, the learning capacity is usually null or very limited, whereas in the MCI, although it has diminished, a certain ability to learn new information may remain .
People with dementia are usually unable or have many difficulties to perform tasks such as handling money, go shopping, orient themselves on the street, etc. On the other hand, people with MCI usually manage more or less well for this type of task.
The most typical DCL deficits are memory loss, naming problems and decreased verbal fluency, so the unique presentation of these 3 deficits (of low severity) makes the diagnosis of MCI more likely than of Dementia.
All DCL deficits are much less serious. To quantify it, a useful screening tool is the Mini-Mental State Examination (MMSE). A score between 24 and 27 in this test would support a diagnosis of MCI, a score of less than 24 on the diagnosis of Dementia.
Markers of mild cognitive impairment
Since mild cognitive impairment increases the risk of developing an Alzheimer-type dementia, current research has focused on determining markers of both MCI and Alzheimer’s.
Although there are still no clear markers, there are several biological, behavioral, psychological and neuropsychological markers that allow us to differentiate both pathologies and predict which patients with MCI can develop dementia.
One of the main biomarkers of Alzheimer’s disease (AD) are the peptides in the cerebrospinal fluid.
In the neurons of people with Alzheimer’s disease, greater amounts of Beta-amyloid, T-Tau and P-Tau proteins have been detected.
When patients with MCI present high levels of these proteins in their brain, it is more than likely that they develop AD, however, if they present normal levels of these proteins the evolution towards AD becomes very improbable.
Behavioral and psychological markers
A study conducted by Baquero in 2006 estimated that 62% of patients with MCI present some psychological or behavioral symptom. The most frequent are depression and irritability.
Likewise, authors such as Lyketsos, Apostolova and Cummings, defend that symptoms such as apathy, anxiety and agitation (typical of depressions) increase the probability of developing AD in patients with mild cognitive impairment.
According Íñieguez, those patients with DCL presenting a fairly significant language and implicit memory or a marked deterioration alteration of the episodic memory and working, are more likely to develop AD patients DCL with another pattern of deficits.
Thus, by way of conclusion, it seems that the limits between mild cognitive impairment and dementia are not clearly defined.
The DCL could be defined as a cognitive decline of low intensity that does not diminish in excess the day to day of the person, but that in some cases can suppose a previous phase to a serious, progressive and chronic demential disorder.
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And what else do you know about the DCL? Explain to me how you interpret this disorder. I’m interested in your opinion Thank you so much!