The cause of her memory lapses was unknown. She had her suspicions, but that was all they were. Considering the hard life she'd lived since being pulled out of her broom cupboard, her mental issues could be any number of things. Maybe she was Crucioed too many times. After all, the Longbottoms eventually went mad after their intense bout of torture. Did the curse have the same effect if it was applied over the course of many years? If so, she wasn't surprised that a number of other Death Eaters seemed a bit barmier than they used to be. Or maybe she could blame physical damage for her problems. The first real episode she experienced was when she was still practically a newlywed. Antonin hadn't yet raised his hand to her outside of training, but there were plenty of other incidents over the years she was a Death Eater where she suffered damage to her head. She lost count the number of concussions she could boast of. There was always a possibility that the illegal potions she kept stashed away in her desk in the Ministry were to blame. Practically harmless if used sparingly, she'd been known to take too many of them when it suited her purposes to forget what she was doing. Perhaps her problems were due to a combination of all of those factors. It was possible she would never get to the bottom of the mystery.