Researchers can’t find any examples of repressed memory in literary works going back further than 200 years:
In an unusual study, a group of psychiatrists and literary scholars, led by Harrison Pope of Harvard Medical School, recently argued that the psychiatric disorder known as dissociative amnesia (often called repressed memory) is a "culture-bound syndrome" — a creation of Western culture sometime in the 19th century.
Pope pointed out that Shakespeare, Homer and other pre-19th-century writers show numerous characters suffering from other psychiatric disorders: the disjointed thinking that we call schizophrenia, or the persistent sadness that marks depression. Because art draws its inspiration from life, Pope said, this shows that those disorders have been around forever.
I want to come up with an example of trauma-related amnesia in older literature, but… I can’t remember one.
It’s been argued that contemporary literature remains ignorant of contemporary neurobiology and so continues to construct characters based on outdated notions of how the brain actually works. Could it be that there was a similar situation in ancient literature–that there were storytelling conventions that prevented writers from acknowledging brain disorders that nonetheless existed?
This reminds me of Julian Jaynes’ theory from back in the 70s; his analysis of ancient texts led him to conclude that humans were not conscious until a few thousand years ago. He said there are no examples of introspection in the Iliad, for example; characters simply hear the voices of the gods, rather like schizophrenics do, and that this indicates that humans had a different mental structure than they do now.