a loss of memory-access to events that occurred, or information that was learned, before an injury or the onset of a disease. It tends to negatively affect episodic, autobiographical, and declarative memory while usually keeping procedural memory intact with no difficulty for learning new knowledge.
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In extreme cases, individuals may completely forget who they are. Generally, this is a more severe type of amnesia known as global or generalized amnesia. However, memory loss can also be selective or categorical, manifested by a person's inability to remember events related to a specific incident or topic.
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The causal explanation of retrograde amnesia is still under investigation.
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