Semantic Dementia: causes, symptoms and treatment

Like many other brain processes, human memory cannot be defined as a single function responsible for saving, encoding, retaining and recovering everything that surrounds us. Rather, it is divided into different types based on the way it works. When these systems fail, alterations such as semantic dementia appear., which we will address throughout this article.

But first of all and to clarify terms, what is semantic memory? Semantic memory gives us the ability to store everything in our long-term memory. Specifically, it refers to the memory of meanings, understandings and other conceptual knowledge.

The alteration in this type of memory causes disorders such as semantic dementia. Which manifests itself through difficulties in language, or the recognition of objects or faces. Even so, people who suffer from this type of disease can lead a relatively normal life.

• Recommended article: "Semantic memory: functioning and associated disorders"

What is semantic dementia?

Semantic dementia is a progressive neurodegenerative disorder whose focus of action is centered on language. This disorder is unique in presenting a gradual loss of semantic memory, both verbally and nonverbally.

People who suffer from it gradually lose their language and show an impoverishment of semantic knowledge.. This leads to great difficulties in naming, understanding and recognizing objects, in addition to remembering names and faces.

Causes

The main cause of semantic dementia is frontotemporal lobe degeneration (FTLD); being one of the three clinical syndromes mostly associated with this degeneration.

To clarify these terms a bit, the main functions of the temporal lobe have to do with the memory, with the dominant temporal lobe being involved in recalling words and names of objects; and the non-dominant one is in charge of our visual memory.

This injury can be caused by:

• Brain atrophy
• multiple infarcts
• excess alcohol
• intracranial tumors
• Normal pressure hydrocephalus
• Chronic drug poisoning
• Multiple sclerosis
• brain trauma
• AIDS

Symptoms

Semantic dementia is characterized by presenting two main symptoms:

1. Perceptual disorder: associative agnosia and prosopagnosia

The person suffering from this disorder is unable to recognize or understand visual stimuli, specifically faces, objects or names.

This makes it difficult for the patient to interact with others and to lead a normal life in society.. Which supposes an added risk of social exclusion. It is not difficult to understand the frustration that can be felt by not being able to recognize the people around you; including, of course, your loved ones.

2. Language deficit: fluent but empty language

During the beginning of the disorder, the patient manifests difficulties in finding the correct words to express himself; compensating for it by using other associated terms. For example, if you wanted to say pen, you might say ink or pen.

As the disease progresses, the meaning of the most common words is also lost.. Therefore, he could no longer use ink to refer to the pen, but would use more generic words such as utensil or instrument.

Gradually the language will become much poorer; ending up presenting an incomprehensible speech. In addition, all these difficulties will also appear in written language, so that the patient's communication with his environment will be increasingly complicated.

As an addition, semantic dementia can present many other characteristics:

• anomie
• Attention deficit
• Alterations in episodic and verbal memory
• Difficulty matching objects
• Changes in mood and social behavior

Diagnosis and prognosis

Although there is no cure for semantic dementia, early diagnosis coupled with therapy pharmacology are key to a good functioning of the patient and, consequently, to improve the prognosis of the patient. patient; giving you a better quality of life.

Since dementing illnesses are difficult to diagnose, it is essential to take into account the history of the illness, and supplement patient information with family interviews to further investigate changes in behavior and personality.

There are three forms of diagnosis that are most successful. They are the following.

1. neuropsychological tests

These tests include both verbal and non-verbal tasks, and are specified in the Concrete and Warrington's Abstract Word Synonym Test, or Howard and Patterson's Pyramids and Palms Test (1992).

2. Neuroimaging techniques

Through the use of magnetic resonance imaging, a characteristic pattern of atrophy can be observed in the temporal lobes (especially in the left), affecting to a greater extent the lower and previous.

Thanks to these techniques, semantic dementia can be differentiated from other subtypes of lobar degeneration such as frontotemporal dementia or progressive non-fluent aphasia.

3. Histopathology

Almost all patients diagnosed with this type of dementia have positive results for ubiquitin and TDP-43.

Treatment

As noted above, there is no cure for this disorder. But if the administration of pharmacological therapy is usual to compensate for the effects associated with this disease. Some of these drugs are:

1. Atypical neuroleptics

Also called atypical antipsychotics. They act on serotonin receptors as well as dopaminergic receptors; being used in this case to treat the aggressive conducts and the agitations of the patient.

2. serotonin reuptake inhibitors

Commonly called antidepressants. This drug increases the levels of serotonin inhibiting its reuptake, thus relieving depressive symptoms, compulsions, etc. that the person can present.

3. Benzodiazepines

This drug is a psychotropic medication (acts on the central nervous system), and is characterized by its sedative effects, anxiolytics and hypnotics, among others. In semantic dementia it is used to cushion anguish, anxiety and insomnia.