Differences between amnesia and dementia
Amnesia is a clinical manifestation involving the loss or alteration of memory, and can occur due to multiple causes, such as trauma, neurological disease, or mental disorder. This condition may be part of another condition known as dementia, a clinical picture that includes cognitive, motor, and functional impairments that go beyond memory loss alone. And although they share some characteristics, there are several differences between amnesia and dementia .
Throughout the article we explain what amnesia and dementia are, and discuss the main differences between them.
What is amnesia?
Amnesia is a condition in which a person’s memory is lost or impaired . This condition may have organic or neurological causes (from brain damage, physical injury, neurological disease or the use of certain substances) or functional or psychogenic causes (psychological factors, mental disorders, post-traumatic stress or psychological defence mechanisms).
There are two main types of amnesia: antegrade amnesia (where the ability to memorize new things is affected or lost because data is not transferred correctly from conscious short-term memory to permanent long-term memory); and retrograde amnesia (where a person’s pre-existing memories are lost in conscious recall, beyond an ordinary degree of forgetfulness, even though they may memorize new things that occur after the onset of amnesia).
Antegrade 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 amnesia, a state of confusion and memory loss that occurs after a traumatic brain injury. Amnesia that occurs due to psychological factors is usually referred to as psychogenic amnesia.
Many types of amnesia are associated with damage to the hippocampus and other related areas of the brain that are used in encoding, storing and retrieving memories. If there is a blockage in the pathways along which information travels during the encoding or memory retrieval processes, or if entire regions of the brain are missing or damaged, then the brain may be unable to form new memories or retrieve some old ones.
Dementia: What is this disorder?
Dementia is the term used to define a class of disorders characterized by the progressive deterioration of thinking ability and memory as the brain becomes damaged. Usually, when memory loss is severe enough to interfere 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 disorders: aphasia (loss of ability to produce or understand language), apraxia (inability to perform learned movements), agnosia (difficulty recognizing and identifying objects or people without impairment of the senses), or executive dysfunction (inability to plan, organize, or reason).
The most common type of dementia is Alzheimer’s disease , which accounts for 50-75% of all dementias. The second most common type, which accounts for up to 20% of dementia cases, is vascular dementia, which has similar symptoms to Alzheimer’s disease but usually results from damage to the brain caused by a blood clot or a hemorrhage that cuts off the brain’s blood supply due to trauma.
Dementia can be caused by specific events such as traumatic brain injury or stroke, or it can develop gradually as a result of a neurodegenerative disease that affects the brain’s neurons or as a secondary symptom of other disorders such as Parkinson’s disease. Some drugs used to treat other age-related diseases and conditions can also have a detrimental effect on memory and speed up the onset of dementia.
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 diseases or more serious conditions, and not only as a symptom or a clinical manifestation.
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 altered, whereas in dementia, as we have seen above, alterations in language, attention or problem-solving ability may occur, regardless of the memory problems that the demented patient may have.
People suffering from dementia see their ability to adequately execute everyday tasks diminished , something that is not so evident in subjects with amnesia. In addition, dementia usually worsens over time and cognitive abilities are progressively reduced; however, the vast majority of amnesias are reversible, except for those that occur precisely as a clinical sign of ongoing dementia.
Ultimately, amnesia is more of a symptom that can occur as part of dementia, but does not have to be the result of dementia, and usually includes only memory loss in its various forms; and dementia is a much more global impairment of brain functioning and involves the alteration of multiple cognitive areas that go beyond mental abilities, including motor and functional impairments.
- 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.