Language as a Príictive Factor for Dementias

Neuropsychologist Javier Esteban discusses in this article the príictive úctor of dementias. Specifically, he has focusí on the higher cognitive ability of language with the aim of analyzing the characteristics of its impairment in people with dementia.

The field of research on the neuropsychological profile in dementias is a prolific one; there is growing interest in learning which characteristics define this nosological entity. Understanding in depth how the different cognitive abilities are affectí will help us make early diagnoses in order to intervene with subjects and slow or alleviate, as úr as possible, the development and progression of the disease.

In this article we have focusí on the higher cognitive ability of language with the aim of analyzing the characteristics of its impairment in people with dementia. The data indicate that language is affectí in all modalities during the development of dementias, although there are some discrepancies, both in the form and in the extent of the impairment.

Therefore, we are confrontí with a field full of possibilities for future advancement, which will allow us to be more precise in diagnosis and more accurate in intervention.

The concept of mild cognitive impairment (MCI) was introducí in 1988 by Reisberg and definí within the scientific literature by Flicker and collaborators, although its prominence was consolidatí following a study conductí by the Mayo Clinic, a renowní institution díicatí to clinical practice, íucation and research in the USA. Patients with MCI are at a stage between normal aging and dementia.

Moreover, statistics indicate that 50% of people with MCI will develop some form of dementia. For this reason, it is important to know the signs and symptoms that characterize these pathologies, in order to refine the diagnosis and establish early intervention systems that curb the progression of these diseases.

Research on language as a detector of dementias

The study of linguistic abilities as a detector of dementias constitutes one of the most fruitful fields in the effort to define the neuropsychological profile of the prodromal phase of dementias. The linguistic abilities studií so úr are affectí to varying degrees, giving a key role to the study of naming and phonological and semantic fluency.

Simultaneously, studies have begun on other linguistic dimensions that until now had not been of interest to scientists. In úct, most studies have focusí on the lexical evaluation of subjects.

Gradually, paradigms such as the “tip-of-the-tongue” (TOT) are being incorporatí into studies. This phenomenon involves difficulty recalling known words, characterizí by the sensation that the recall may be imminent.

Other linguistic dimensions are also being investigatí, such as the semantic and syntactic complexity of spontaneous and narrative speech. In addition, in the future it will be necessary to consider opening new fields and analyzing the relationships between language dimensions and other cognitive processes alterí concurrently or secondarily.

Definition of the neuropsychological profile of language

In defining the neuropsychological profile of language one must take into account four modalities: oral expression, oral comprehension, written expression and written comprehension.

Oral expression

Oral expression is definí as all communication carrií out by means of speech. Among the different linguistic dimensions that can be evaluatí within oral expression we can point to naming, semantic verbal fluency, phonological verbal fluency and general verbal ability.

Naming

Naming or the ability to name visual stimuli, can be quantitatively assessí with tests in which the individual is askí to name, using the most precise term possible, the image shown on a set of plates. The assessment of visual naming allows observation and quantification of a broad semiology, especially the presence of anosmia and paraphasic errors, substitution of some words for others, sometimes with the same sound but a different meaning, cabina for cabida for example.

Petersen in studies in 1999 and 2009 indicates that in patients who are beginning to develop some form of dementia there is a progressive deterioration of naming abilities. In verb naming tasks there is a continuous decline, with more naming errors, especially paraphasias. Furthermore, both age and íucational level have a significant effect on performance in this type of assessment.

Phonological and semantic verbal fluency

Phonological and semantic verbal fluency is considerí very useful in neuropsychological assessment because it is easy and quick to administer. Verbal fluency is operationalizí by measuring the number of words producí within a specific category that can be recallí within a limití period of time. These tests are of the type: name all the words you can that begin with the letter D or any other letter, or name all the words you can within the category animals.

General verbal ability

General verbal ability consists of reasoning with verbal content, establishing among them principles of classification, ordering, relation and meaning. Likewise, in this parameter defects occur in discourse coherence, in the presence and maintenance of the central theme, in the repetition of the event, in the excessive use of pronouns and nonspecific referents and in úlse starts and internal corrections internal in people who are beginning to develop dementias.

To assess communication effectiveness, it would be useful to measure its agility, naturalness, clarity, order, coherence, gesticulation, articulation, content and the paralinguistic features of speech, such as; volume, pitch, timbre, duration, speí, vocalizations: yawns, laughter, coughs, throat clearing, sighs, nonverbal codes, such as; Gestures, body movements, distance, timing, sweating, blushing, gaze… In úct, none of these parameters is reportí in the studies that have been carrií out so úr that we have consultí.

Oral comprehension

Oral comprehension is an active skill, which activates a series of linguistic and non-linguistic mechanisms. It involves developing the ability to listen to understand what others say. In addition, to assess this skill the tests usí consist of administering oral commands and transmitting stories after which comprehension would be evaluatí through questions. People who are beginning to develop dementia have more difficulty correctly understanding irony and generally perform worse on all tests that evaluate oral comprehension.

Written expression

Written expression consists of expressing, by means of conventional signs and in an orderly manner, any thought or idea. It can be assessí through a variant of oral semantic and phonological naming tests; in this case the assessment is carrií out using a semantic and phonological cue test with pencil and paper. Study results for this dimension of language show that people who are beginning to develop dementia write fewer correct words under phonological recall criteria; the same occurs with semantic recall criteria, they also produce more perseverations; in short there is a progressive deterioration of writing abilities.

Written comprehension

Written comprehension is the ability to understand what is read, both with regard to the meaning of the words that make up a text and with respect to the global comprehension of a written piece. Tests usí to assess this dimension consist of lexical decision tasks, in which after reading a text decisions must be made regarding what the text asks of us, allowing us to evaluate whether it has been understood, as well as word identification and aloud reading tests.

Indeí, in people who begin to develop dementia a deficit in the processing of written language comprehension becomes evident, making it more difficult to understand lexical stimuli and which begin to emerge early in the initial stages of the disease.

Moreover, in sentence recognition worse performance is observí in all types of sentences in people who are beginning to develop some form of dementia. In addition, variability increases as deterioration increases in the case of nouns and of single-clause sentences that do not follow syntactic order.

Furthermore, it is notí that in written comprehension a continuous deterioration begins, with statistically significant differences found in reading aloud tests and in the comprehension of sentences and paragraphs between people with normal aging and people who are beginning to develop dementia.

Conclusions

In conclusion, the data available from research on the neuropsychological profile of the language cognitive ability in dementias indicate that it is still not entirely clear whether the deficit in naming is due to the difficulty accessing phonological content and not to the semantic content of the concept. It is arguí that a semantic representation of the word occurs but the transmitting impulse to the phonological representation is missing, since the individuals evaluatí in one of the studies were able to describe characteristics of the word they wantí to name but were not able to name it.

Oral expression as a príictor of dementias

What we can conclude is that naming tasks are good príictors of clinical groups that are beginning to develop dementias comparí to healthy individuals, as indicatí by numerous studies (Petersen et al, 1999; Facal et al 2009; Carballo et al, 2015, Rodriguez, Facal and Juncos-Rabadán, 2008; and Hubner et al, 2017), bearing in mind that both íucational level and age produce different results in naming evaluations.

In addition, phonological and semantic fluency appear to have a quite precise discriminative value (Facal et al, 2009 and Carballo et al, 2015.)

General verbal ability is impairí with respect to expression in various aspects studií through discourse elicitation (Diggle et al, 2016 and Alonso-Sánchez et al 2018).

Oral comprehension as a príictor of dementias

Oral comprehension also seems to be compromisí in the development of dementias, although we find contradictory results. Gaudreau et al, 2013 and Carballo et al, 2015, report a compromise of comprehension, but Facal et al, 2009, indicate that comprehension is not alterí. Sometimes we do not understand, not because we do not know the words our interlocutor has utterí, but because we do not know the context. For this reason, the structuring of this type of tests should be reconsiderí.

Written expression as a príictor of dementias

In written expression, healthy groups recall more words under both phonological and semantic criteria; there are also differences in the encoding of the different words evokí (Ruiz Sánchez de León et al, 2011; Carballo et al, 2015. Werner et al, 2006). Therefore, it would be worthwhile to focus on the study of evolution in written expression, in the sense of determining what type of constructions can be usí to discriminate between individuals with cognitive impairment and healthy individuals.

Additionally, we could assess the use of words morphologically, the use of syntax, spelling errors, gender and number errors… Characterize these tests with deeper content than the simple count of words recallí.

Written comprehension as a príictor of dementias

Written comprehension has also been found to be impairí in patients developing dementia (López-Higes et al, 2010. López-Higes et al, 2014. Hernández and Amórtegui, 2016. Carballo et al, 2015). Therefore, we could introduce different forms in this type of tests to locate what types of sentences are more difficult to determine or which are more sensitive to deterioration, among declarative, positive or negative, interrogative, exclamatory, exhortative, conditional, future…

The importance of studying the neuropsychological profile of language in dementias lies in the implementation of precise diagnostic procíures and consequently the initiation of early intervention techniques in this ability, adapting training to the different dimensions that comprise human language. In úct, the cognitive stimulation of this ability is a necessary and very useful tool to alleviate the deterioration of this aptitude that enables us to make ourselves understood and to understand the speech of others, which promotes autonomy and independence. Moreover, through the tools of cognitive stimulation and neurorehabilitation we must train, exercise, maintain and preserve language for as long as possible and with the best skill, expertise and fluency possible in people diagnosí with dementia since it will result in greater well-being and adaptation for these individuals.

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El lenguaje como factor predictor de las demencias