The ability to read is a fundamental skill in today’s society. Academic and working life generally require mastery of this skill. This is why, from childhood onwards, we learn to give meaning to the words we form through written language, something that, although it may seem relatively simple for an adult if it has been done from childhood, requires a high level of processing and a great number of operations and mental transformations in order to be carried out successfully.

However, sometimes people who have possessed and correctly developed the ability to read lose that possibility for some reason, completely losing the ability to read. This circumstance corresponds to alexia , which we will talk about throughout this article.

Alexia: basic definition

It is called alexia a written language disorder characterized by the partial or complete loss of reading ability, being produced by the appearance of some kind of brain injury. It is therefore a secondary type of affectation, that is to say, derived from another alteration, which can even be interpreted as a symptom of the latter.

It is considered a type of visual agnosia, that is, the absence of recognition of any type of perceptible stimulation through sight. In this case, the subject loses the ability to understand written words , and it is impossible or at least very difficult for him to code them in order to transform the spelling into the phoneme, even though he has previously possessed this ability.

Types of alexia

Although alexia implies the loss of reading ability, it does not always appear in the same way, and there may also be other problems or different deficits. Among the main types we can find

Alexia pure or without agraphy

This type of alexia is one in which only severe difficulties or the complete impossibility of visual recognition of letters or words appear, but the subject is able to write correctly (in spite of not being able to understand what he has written). It is also called blindness to words . It is possible for the subject to recognise some single word that is frequently used.

It is not the most common, since it usually involves a bilateral affectation in such a way that visual information cannot pass to the areas that interpret and generate the language, in the left hemisphere. This usually corresponds to problems in the occipital area of the brain , in the fusiform, lingual and/or angular gyrus, or the uncus.

Central Alexia or with agraphy

As in the previous case we find an alteration and impossibility or great difficulty in the recognition of written words, but also in their production. In other words, in this case we find that the subject can neither read nor write. It is possible that anomie also appears , having problems in identifying objects and visual stimuli beyond reading and writing.

This type of alexia usually corresponds to lesions in the angular gyrus, which is responsible for processing information in such a way that the spelling or letters are changed into phonemes or sounds and vice versa, which is necessary for both reading and writing. It is also related to lesions in the parietals or in the fibres from the temporal and occipital lobes.

Anterior Alexia or with aphasia

Also called frontal alexia, we are facing a circumstance in which not only are there alterations at the reading level but also in the production of speech. In this case, the lesion is generally produced at a more frontal level, and its functionality is similar to that of a subject with Broca’s aphasia . It is usually the case that there are fewer problems with words familiar to the subject than with other alexias.

Differentiation from other situations

It is important to take into account that in alexia we are facing a situation in which the subject already knew how to read and there has been a loss of this ability, not being considerable as alexia the cases of those people who have never learned to do so, that is, illiteracy.

It is also relevant to differentiate it from developmental dyslexia , which would be that neurodevelopmental disorder (which implies that at a neuronal level what exists is an atypical organization of brain development and not a lesion itself) in which a difficulty in reading and writing appears from childhood and in which there has never been a greater degree of capacity than that which the subject expresses at that time (not a loss but rather a difficulty).

Finally, it should be noted that alexia is not derived from the absence of visual perception itself: the subject can see the words and his eyes work with sufficient precision to perceive them, the problem being the coding and transformation of these words into something meaningful.

Possible causes

Alexia is considered to be a type of agnosia and a reading disorder generated by some type of brain injury. But the causes of such injury can vary greatly. It should also be taken into account that the lesion can appear in different locations of the nervous system, from the angular and/or supramarginal turns to the fibers coming from the occipital or temporal lobes, passing through the lingual and fusiform turns, among others. Among the main causes of the appearance of alexia we can find the following events.

1. Stroke

One of the main causes of alexia is suffering some kind of stroke or ictus, we are talking about ischemia (blockage of the blood vessel that prevents blood from reaching certain areas) or hemorrhage (rupture of the vessel). Depending on the areas affected, the death of the brain tissue may cause the loss of reading ability .

2. Head trauma

Another classic reason for the appearance of alexia is the fact of having suffered some kind of head trauma. Traffic accidents, accidents at work or aggressions are some of the causes that make some type of alexia appear.

3. Dementias and other neurodegenerative disorders

Alexia can occur during the course of the deterioration generated by some type of dementia, such as Alzheimer’s, or other similar disorders. Depending on the disorder itself, the difficulty, worsening and impossibility of reading may appear in different phases of the disease .

4. Brain tumor

Another possible cause of alexia is found in the appearance of brain tumors that affect, paint or compress the brain areas and nerve fibers involved in the reading process .

5. Brain infections

Alexia can also appear in the face of certain infectious processes that end up affecting the brain. Some typical ones are meningitis or encephalitis .

Treatment of Alexia

The treatment of alexia is not simple, taking into account that we are facing a phenomenon derived from some kind of brain injury, and in fact we may be facing a permanent damage. However, this does not mean that it is not possible to achieve different levels of recovery, depending on the areas injured or the degree of involvement of the injury, or compensation of functions.

The type of treatment will depend on these and other factors, and for its implementation will require a multidisciplinary team working in disciplines such as neurology or psychology , in addition to other health or even social specialties.

The first thing will be to determine and treat the cause of the appearance of the alexia. Mostly an early diagnosis will allow a better work at the level of treatment and may prevent a worsening (for example, if we are facing an infection or a tumor these can grow and generate more damage).

It will be necessary to use an individualized rehabilitation program , being usual the use of language therapies and different types of cognitive stimulation. Psychoeducation will also be important for both the person and his/her environment, so that they can understand what has happened and know how to apply different means so that the difficulties do not represent a limitation. It can also be important to work on the affective sphere, self-concept and self-esteem, which can be altered by the presence of deficits.

Bibliographic references:

  • Junqué, C. and Barroso, J. (Coords.) (2009). Manual of Neuropsychology. Madrid: Síntesis.
  • Portellano, J.A. (2005). Introduction to neuropsychology. Madrid: McGraw Hill.