Semantic Dementia: causes, symptoms and treatment

This degenerative disorder affects language, making it poor, incoherent and incomprehensible.

Like many other brain processes, human memory cannot be defined as a single function responsible for storing, encoding, retaining and retrieving everything that surrounds us. Rather, it is divided into different types according to 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.

Alterations in this type of memory cause disorders such as semantic dementia.. This is manifested by difficulties in language, or the recognition of objects or faces. Even so, people suffering 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 is on language. This disorder is unique in that it presents a gradual loss of semantic memory, both verbal and non-verbal.

Sufferers progressively lose language and show an impoverishment of semantic knowledge.. This leads to great difficulties in naming, understanding and recognizing objects, as well as 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 little, the main functions of the temporal lobe have to do with memory, being the dominant temporal lobe the one involved in the memory of words and names of objects; and the non-dominant one the one in charge of our visual memory.

This lesion may have its origin in:

• Cerebral atrophy
• Multiple strokes
• Excess of alcohol
• Intracranial tumors
• Normal pressure hydrocephalus
• Chronic drug intoxications
• Multiple sclerosis
• Traumatic brain injury
• AIDS

Symptoms

Semantic dementia is characterized by two main symptoms:

Perceptual disorder: associative agnosia and prosopagnosia 2.

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

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

2. Language deficits: fluent but vacuous speech

During the early stages of the disorder, the patient manifests difficulties in finding the right words to express him/herself; compensating by using other associated terms. For example, if he/she wants to say pen, he/she may 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; eventually presenting an incomprehensible speech. In addition, all these difficulties will also be present in written language, so that the patient's communication with his environment will become increasingly complicated.

In addition, semantic dementia may present many other characteristics:

• Anomia
• Attention deficit
• Episodic and verbal memory disturbances
• Difficulties in matching objects
• Alterations in mood and social behavior.

Diagnosis and prognosis

Although there is no cure for semantic dementia, early diagnosis along with pharmacological therapy is key to good patient functioning and, consequently, improving the patient's prognosis, giving him/her a better quality of life.

Since dementia diseases are complicated to diagnose, it is essential to take into account the history of the disease, and to complement the patient's information with interviews with family members, and thus thoroughly investigate changes in behavior and personality.

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

Neuropsychological testing

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

Neuroimaging techniques

Using magnetic resonance imaging, a characteristic pattern of atrophy can be observed in the temporal lobes (especially in the left lobe), affecting the inferior and anterior areas to a greater extent.

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. However, it is common to administer drug therapy to compensate for the effects associated with this disease. Some of these drugs are:

1. Atypical neuroleptics 2.

Also called atypical antipsychotics. They act on serotonin receptors, as well as on dopaminergic receptors; they are used in this case to treat aggressive behaviors and patient's agitations.

2. Serotonin reuptake inhibitors

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

3. Benzodiazepines

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