Differences between amnesia and dementia

Amnesia is a clinical manifestation that involves memory loss or impairment, and can occur due to multiple causes, such as trauma, neurological disease, or disorder mental. This condition can be part of another condition known as dementia, a clinical picture that includes cognitive, motor and functional alterations that go beyond only the loss of memory. And although they share some characteristics, there are several differences between amnesia and dementia.

Throughout the article we explain what both amnesia and dementia consist of, and we address the main differences between one and the other.

• Related article: "The different types of amnesia (and their characteristics)"

What is amnesia?

Amnesia is a condition in which a person's memory is lost or altered. This condition can have organic or neurological causes (due to brain damage, physical injuries, neurological diseases or the use of certain substances) or by functional or psychogenic causes (psychological factors, mental disorders, post-traumatic stress or defense mechanisms psychological).

There are two main types of amnesia: anterograde amnesia (where the ability to memorize new things is impaired or lost because data is not transferred correctly from short-term conscious memory to long-term permanent memory term); and retrograde amnesia (where a person's pre-existing memories are lost in conscious recall, beyond of an ordinary degree of forgetfulness, even though they can memorize new things that occur after the onset of amnesia).

Anterograde amnesia is the more common of the two. Sometimes these two types of amnesia can occur together and are called total or global amnesia. Another type of amnesia is post-traumatic, a state of confusion and memory loss that occurs after a traumatic brain injury. Amnesia that occurs due to psychological factors is generally known as psychogenic amnesia.

Many types of amnesia are associated with damage to the hippocampus and other related areas of the brain. used in the encoding, storage and retrieval of memories. If there is a blockage in the pathways along which information travels during memory encoding or retrieval processes, or if entire regions of the brain are missing or damaged, so the brain may be unable to form new memories or regain some ancient.

Dementia: what is this disorder?

Dementia is the term used to define a class of disorders characterized by progressive impairment of thinking ability and memory as the brain is damaged. Generally, when memory loss is so severe that it interferes with normal daily functioning, the condition is called dementia. Less severe memory loss is known as mild cognitive impairment.

Dementia is characterized by severe loss of memory and cognitive ability (primarily in the areas of attention, language, and problem solving), along with one or more of the following: aphasia (loss of the ability to produce or understand language), apraxia (inability to carry out learned movements), agnosia (difficulties in recognizing and identifying objects or people without damage to the senses) or executive dysfunction (inability to plan, organize or to reason).

The most common type of dementia is Alzheimer's disease, which represents 50-75% of all dementias. The second most common type, accounting for up to 20% of dementia cases, is vascular dementia, which has symptoms similar to Alzheimer's disease but usually results from damage to the brain caused by a blood clot or hemorrhage that cuts off the brain's blood supply due to a trauma

Dementia can be caused by specific events such as traumatic brain injury or stroke, or it can develop gradually as the result of a neurodegenerative disease affecting neurons in the brain or as a secondary symptom of other disorders such as Parkinson. Some drugs used to treat other age-related diseases and conditions can also have a detrimental effect on memory and accelerate the onset of dementia.

• You may be interested: "Types of dementias: the 8 forms of loss of cognition"

Differences between amnesia and dementia

To address the differences between amnesia and dementia, we must look at what defines each of these clinical pictures. Amnesia is a symptom that can occur in many situations and for different causes., and this is something that differentiates it from a condition such as dementia, since the latter is defined as a set of disorders that can lead to other more serious diseases or conditions, and not just as a symptom or manifestation clinic.

Another clear difference between amnesia and dementia is the variety of cognitive symptoms that occur in both conditions. In amnesia, memory is usually the only cognitive function that is impaired, while in dementia, as we have seen previously, they can alterations in language, attention or the ability to solve problems occur, regardless of memory problems that the patient may present demented.

People with dementia see their ability to adequately perform daily life tasks impaired, something that does not usually occur so obviously in subjects with amnesic pictures. Furthermore, dementia usually worsens over time and cognitive abilities progressively decline; however, the vast majority of amnesias are reversible, except for those that present precisely as a clinical sign of ongoing dementia.

Ultimately, amnesia is more of a symptom that can present as part of dementia, but not has to be the result of it, and usually includes only memory loss in its various shapes; and, for its part, dementia is a much more global alteration of brain functioning and involves the alteration of multiple cognitive areas that go beyond memory capacities, and include alterations at the motor and functional.

Bibliographic references:

• American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders. Fifth edition. DSM-V. Masson, Barcelona.
• Belloch, A.; Sandín, B. and Ramos, F. (2010). Manual of Psychopathology. Volume I and II. Madrid: McGraw-Hill.