What Is Amnesia? What Causes Amnesia?

Memory formation is an important function of the human brain. It not only allows us to reminisce about past vacations, recall the punchline to a joke, or remember an important date, it is also vital in terms of learning. Everything you have learned, from the day you were born, is as a result of your innate ability to experience something, process that information, and remember it so that you know how to respond to that situation in the future. Given the incredible complexity of the human brain, with its billions of neurone cells and chemicals, it is perhaps not surprising that the scientific processes behind memory formation are not entirely well understood.

Causes of amnesia

Amnesia is a loss of memory that can be caused by an injury or disease in the areas of the brain that deal with memory formation. Hitting your head, falling off a bike or a horse, having a stroke or bleed in the brain – all of these things and more can cause amnesia, not to mention genetic and/or degenerative disorders such as Alzheimer’s Disease, substance abuse (e.g. taking illegal drugs or abusing alcohol), and trauma.

When we think of amnesia, we often associate it with total memory loss, but in reality, amnesia – which can be temporary or permanent, falls into several different types, which can occur independently or at the same time.

Retrograde amnesia

Retrograde amnesia is the loss of memory or parts of the memory before a certain point in time. This type of amnesia is most often associated with brain injury or an acute condition such as a stroke or hemorrhage, whereby sufferers are unable to recall memories from before the accident or event. Depending on the nature and severity of the injury, retrograde amnesiacs may be unable to recall events in the period leading up to the accident, or may have forgotten information going back much longer.

Anterograde amnesia

This type of amnesia is not so much a ‘loss’ of memory as the inability to create new memories. To use a personal example, my father suffered a brain injury in 1993 – afterwards, he was perfectly able to remember his family and old friends, but found it impossible to remember the name of anyone he met after the injury, no matter how many times he met them.

Dissociative amnesia

This third type of amnesia is fundamentally different from the other two in that it is rarely the direct result of a physical injury or disease. Instead, dissociative amnesia is a psychological phenomenon whereby memories are formed, but are not able to be recalled. This type of amnesia is typically associated with traumatic experiences, for example the repression of the memories of sexual abuse, or bearing witness to a violent attack.

Treatment for amnesia

Treatment for amnesia often includes cognitive therapy, although its success depends on the severity of the causative injury or disorder. Since neurones in the brain are unable to grow back once damaged, any amnesia that results from a permanent injury or degenerative disorder is unlikely to improve. Nevertheless, if the neurones are not permanently damaged then partial or full regain of memory can be achieved.

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Lisa Martin

Lisa Martin is a qualified biology teacher and experienced freelance science writer from Warwickshire in the UK. She is fascinated by how the human body works and is particularly interested in writing about new research and discoveries in science and medicine.

Follow Lisa on Twitter: lisaamartin1

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