- Extreme mood swings — Eden can swing from anger to sadness to romantic emotions at the drop of a hat, often within the same chapter and occasionally even within the same paragraph
- Intense and unstable relationships with family and loved ones, swinging from extreme dislike to extreme closeness — Eden waffles constantly between hating Bramford and crushing intensely on him, again often within the same chapter and even within the same few paragraphs
- Impulsive and dangerous behaviors — Eden is constantly doing stupid things that endanger herself and others around her, such as wandering off into the jungle by herself or blurting out confidential information to others
- Substance abuse — Eden is addicted to a drug called "oxy" (it's stated that much of the population takes drugs, but Eden is the only character we actually see taking them)
- Recurring suicidal thoughts or behavior — Eden thinks about killing herself at least once
- Stress-related paranoid thoughts — Eden believes everyone is out to get her just because she's a Pearl
- Distorted or unstable self-image — Eden is obsessed with her own physical appearance
I'm not an expert on mental health or psychiatry, but Eden sure fits a lot of the criteria. And while I think this wasn't at all intentional on the part of the writer, it still explains a LOT of Eden's behavior throughout the book.