Borderline personality disorder - characteristics and causes

Borderline personality disorder is a severe personality disorder whose features include impulsivity, changeable moods, relationship problems and identity problems. It is associated with interpersonal and occupational impairment, an increased risk for suicide and higher rates of treatment in both medical and psychiatric settings. A study of 5,496 twins, between the ages of 18 and 86, from the Netherlands, Belgium and Australia looked into the characteristics of people with borderline personality disorder and attempted to see how much of the condition could be attributed to genetic factors and how much to environmental ones. The study found that women and young people were more likely to have the condition. 42% of the variations in the condition could be explained by genetic factors and 58% by environmental ones.

Distel, M.A. ... [et al] - Heritability of borderline personality disorder features is similar across three countries Psychological Medicine September 2008, 38(9), 1219-1229

Previous studies have shown that about 1% of the population have borderline personality disorder. It can improve over time but it affects the life and development of young adults over decades and about 10% of people with the condition kill themselves. Stress is thought to play an important role in producing the behaviour associated with borderline personality disorder and a study of 135 people in The Netherlands aimed to examine this link more closely. The study compared 44 people with borderline personality disorder, 42 people with psychosis (which is also known to be brought on by stress) and 49 unaffected controls. It found that the participants with borderline personality disorder reacted much more strongly to the stresses and strains of everyday life than people with psychosis and the control group; after stressful events their negative mood increased more and their positive mood decreased more than participants in the other two groups.

Glaser, J.-P. ... [et al] - A momentary assessment study of the reputed emotional phenotype associated with borderline personality disorder Psychological Medicine September 2008, 38(9), 1231-1239