Semantic dementia: causes, symptoms and treatment
Like many other brain processes, human memory can not be defined as a single function responsible for storing, coding, retaining and recovering everything that surrounds us. But it is divided into different types according to the way it works. When these systems fail, alterations like 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 possibility of storing 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 is manifested by difficulties in language, or 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 on language. This disorder is unique in that it presents a gradual loss of semantic memory, both verbally and nonverbally.
People who suffer from it progressively lose language and show an impoverishment of semantic knowledge . This results in great difficulties in naming, understanding and recognizing objects, in addition to remembering names and faces.
Causes
The main cause of semantic dementia is the degeneration of the frontotemporal lobe (DLFT) ; 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, with the dominant temporal lobe being involved in the memory of words and names of objects; and the non-dominant one in charge of our visual memory.
This injury can have its origin in:
- Brain atrophy
- Multiple infarcts
- Excess alcohol
- Intracranial tumors
- Hydrocephalus normotensa
- Chronic poisoning by drugs
- Multiple sclerosis
- Brain trauma
- AIDS
symptom
Semantic dementia is characterized by 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 can lead a normal life in society . What is an added risk of social exclusion. It is not difficult to understand the frustration that can be felt when you can not recognize the people around you; including, of course, your loved ones.
2. Deficit in language: fluid but vacuous language
During the beginning of the disorder, the patient manifests difficulties in finding the correct words to express himself; compensating it by using other associated terms. For example, if you want to say pen, you may say ink or pen.
As the disease progresses, the meaning of the most common words is also lost . Therefore I could no longer use ink to refer to the pen, but I would use more generic words such as utensil or instrument.
Gradually, the language will become much poorer; ending by presenting an incomprehensible speech. In addition, all these difficulties will also be presented in written language, so that the patient's communication with their environment will be increasingly complicated.
In addition, semantic dementia can present many other characteristics:
- Anomia
- Attention deficit
- Alterations in episodic and verbal memory
- Difficulty matching objects
- Alterations in mood and social behavior
Diagnosis and prognosis
Although there is no cure for semantic dementia, an early diagnosis together with pharmacological therapy are key to a good functioning of the patient and, consequently, improve the patient's prognosis; giving it a better quality of life.
Since demential diseases are difficult to diagnose, it is essential to take into account the history of the disease, and supplement the patient's information with interviews with relatives, and thus thoroughly investigate the changes in behavior and personality.
There are three forms of diagnosis that are more successful. They are the following.
1. Neuropsychological tests
These tests include both verbal and non-verbal tasks, and are specified in the tests Concrete and Abstract Word Synonym Test by Warrington, or the Test of Pyramids and Palm Trees by Howard and Patterson (1992).
2. Neuroimaging techniques
Through the use of magnetic resonances, a characteristic pattern of atrophy in the temporal lobes (especially in the left lobe) can be observed, affecting the lower and anterior areas to a greater extent.
Thanks to these techniques, semantic dementia can be differentiated from other subtypes of lobular degeneration such as frontotemporal dementia or non-fluent progressive aphasia.
3. Histopathology
Almost all patients diagnosed with this type of dementia present positive results for ubiquitin and for TDP-43.
Treatment
As noted above, there is no cure for this disorder. But it is usual the administration of pharmacological therapy to compensate 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 behaviors and the agitations of the patient.
2. Serotonin reuptake inhibitors
Commonly called antidepressants. This drug increases serotonin levels by inhibiting its reuptake, thus relieving depressive symptoms, compulsions, etc. what the person can 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 cushion anguish, anxiety and insomnia.
