Primary progressive aphasia (APP): causes and symptoms
One of the definitions of language is that of the human being's own capacity that he uses to express thoughts and feelings through the word. Unfortunately, there are cases in which this ability is truncated. One of these cases are aphasias, which are known to disable people for speech.
A type of aphasia that is rare is primary progressive aphasia (APP) which is characterized by a progressive degeneration of speech capacity in patients who maintain relatively intact the rest of their cognitive, instrumental or behavioral skills.
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Causes of primary progressive aphasia
Primary progressive aphasia (APP), also called Mesulam aphasia, is a neurodegenerative disease that materializes in a pathology of the linguistic domain .
This develops gradually and occurs in people who do not suffer any other alteration in the other cognitive areas, nor experience alterations in behavior or are limited to the performance of their daily activities.
During the first stages of development of the disease, the patient is completely autonomous in terms of achieving any task, however the degenerative course of this pathology finally leads to generalized dementia.
Contrary to what happens with secondary aphasias, primary aphasias seem to have no specific origin or cause. Even so, certain studies have tried to detect the presence of atrophy patterns associated with this aphasia. Through the use of magnetic resonances, characteristic atrophies of each of the types of aphasia have been observed:
- Lower frontal and insular frontal atrophy in the grammatical APP
- Bilateral anterior temporal atrophy with predominance left in the semantic variant
- Left temporoparietal atrophy in the logopenic variant
Types of primary progressive aphasia
Researchers in this field detail three variants of this type of aphasia in which, as mentioned in the previous section, each of them is associated with an anatomical functional pattern.
These variants are ungrammatical / non-flowing, the semantic variant and the logopenic variant.
1. Agramatical variant
This variant is characterized by presenting itself in the form of very difficult speech and a completely agrammatic production.
To clarify this concept, it should be noted that the agrammatism consists of the emission of short phrases with a very simple structure; omitting the functional expressions, which are those that serve as a link between the words.
The first symptom of the disease tends to be difficulty in planning speech . Which begins to become slow and very laborious.
Certain grammatical errors that are not very important can be detected early by applying oral production tests. In which patients with APP generally make some mistake in sentences with a complex grammatical construction.
2. Semantic variant
Also called semantic dementia, in which the patient presents enormous difficulties when it comes to naming any object or thing ; presenting a normal performance in the rest of the linguistic functions, at least at the beginning of the illness.
During the course of the disease semantic memory deteriorates gradually, while other difficulties appear in understanding the meaning of objects. These difficulties when identifying and accessing knowledge occur independently of the sensory modality in which the stimuli are presented.
There is usually a gradual decrease in the body of knowledge that the patient has about the world around him.
3. Logopenic variant
It is considered the least common variant of the three, which has two characteristic features:
- Difficulty accessing vocabulary
- Errors in phrase repetition
The clearest way to exemplify this type of aphasia is to represent it as the constant feeling of "having something on the tip of the tongue". The patient does not suffer from an agramatism, but rather he finds recurrent difficulties when it comes to finding the words he is looking for; presenting, in addition, phonological errors .
This last point makes us suspect that patients suffering from primary progressive aphasia also present a deterioration in the phonological store; since the understanding of isolated words and short sentences is correct, but difficulties appear when interpreting long sentences.
Diagnosis: Mesulam criteria
There are two different stages when making a diagnosis of primary progressive aphasia:
- Patients must meet the characteristics of Mesulam for the APP without considering any specific variant.
- Once the APP is diagnosed, it will be determined which variant is treated by the evaluation of linguistic cognitive processes.
Mesulam criteria for the APP
These criteria described by Mesulam in 2003 take into account both the diagnostic inclusion criteria and the exclusion criteria. These criteria are the following:
- The language becomes a slow and progressive speech. Both when naming objects, as in syntax or oral comprehension.
- Other activities and functions that do not imply communicative competences intact.
- Aphasia as the most prominent deficit at the onset of the disease. Although the rest of psychological functions may be affected during the course of this, the language is the most damaged from the beginning.
- The APP is discarded if there is presence of strokes, tumors or trauma related to aphasia in the patient's history.
- If there are strange behavioral changes and more evident than the aphasic alteration, the APP is discarded.
- If there are significant alterations in episodic memory, non-verbal memory or visuospatial processes, it will not be considered APP.
- In the presence of parkinsonian symptoms such as stiffness or tremor, APP is ruled out.
There is no cure or medication for the APP. However, there are logopedic therapies that help improve and maintain the patient's communication capacity.
These therapies focus on the person's effort to compensate for the deterioration of language skills . In this way, although the evolution of the disease can not be stopped, the condition can be controlled.
Evolution and prognosis
Although PPP can occur over a wide age range, it is more likely to occur in people between 50 and 70 years of age . As mentioned above, for now there is no cure for PPP, so prognosis of this disease is somewhat demoralizing.
Once the disease has been established, this aphasic disorder tends to progress in a way that eventually leads to severe cases of mutism. But unlike other dementias the patient becomes dependent much later.
Regarding the presence of other additional deficits, language is the only clinical manifestation or, at least, the most predominant. But if there are cases of other alterations at the cognitive, behavioral, extrapyramidal, etc. level. However, it is unknown how frequently dementias become generalized during the course of the disease.