Borderline personality disorder (BPD) is marked by a chronic pattern of instability in personal relationships, impulse control, moods and self-image. Compared with other mental-health problems people with BPD are much more likely to attempt suicide (75%) and to actually succeed in killing themselves (10%). No-one is quite sure about the causes of BPD although it is often linked to child abuse and neglect. Some researchers think it can be linked to what is known as an invalidating childhood environment which is one in which there is a constant rejection of the child's feelings or behaviour, emotional display is punished but tantrums are sometimes rewarded and there is an over-simplification of the skills involved in problem-solving. As a result of this environment children learn not to trust their feelings, have difficulty recognising and regulating their emotions and tend to cope with distress in an unhelpful way. Because people who have been exposed to an invalidating childhood environment have a low tolerance for strong emotions or moods they often turn to impulsive behaviour - such as self-harm and drug-taking - to deal with them in a process known as avoidance of affect. Researchers from the Royal Melbourne Institute of Technology University looked into this theory in a sample of 141 people ranging in age from 18 to 71. They found that those people who said that they had had invalidating mothers were much more likely to display avoidance of affect and BPD features. The study found, in accordance with the theory, that maternal invalidation produced avoidance of affect, which in turn lead to BPD symptoms.
Sturrock, Bonnie A., Francis, Andrew and Carr, Steven - Avoidance of affect mediates the effect of invalidating childhood environments on borderline personality symptomatology in a non-clinical sample Clinical Psychologist July 2009, 13(2), 41-51