Forgetfulness & Dissociation: While it may seem random, forgetfulness is common in abused children. The more severe the abuse, the more severe the forgetfulness. When children frequently experience ongoing episodes of abuse, they learn to dissociate, or “leave” their bodies to cope. Frequent dissociation can cause the child to “space out” during times abuse is not occurring. It can be frightening and confusing for a child when they realize time has passed and they cannot recall what happened. Dissociation can cause the child to forget things they learned (or should have learned) in school, and create academic struggles. They may also forget things friends, siblings, parents and other adults told them. Adults may assume the child is inattentive, stupid, and lazy. Some may even think s/he is lying about not knowing what happened and what they were told. In abusive homes the child may be hurt more for not remembering things they were told. Children who dissociate may be incorrectly diagnosed with ADD/ADHD or learning disabilities. Events and memories in an abused child’s life may come and go, as well as change. This can be just as confusing as the abuse itself. If left untreated, severe dissociation can sometimes turn into DID (Dissociative Identity Disorder, i.e. multiple personalities). Children and adults who have suffered abuse so severe they dissociate should get intense therapy to try and piece things back together, as well as recover from the abuse.
I found this bit particularly interesting as when I had various tests done that resulted in me getting extra time in exams etc it was found that for my intelligence my memory is in an incredibly low percentile (this occurs in less than 1% of the population). I wonder if it had anything to do with the abuse...