There is considerable variability in the course of borderline personality disorder. The most common pattern is one of chronic instability in early adulthood, with episodes of serious affective and impulsive dyscontrol and high levels of use of health and mental health re— sources. The impairment from the disorder and the risk of suicide are greatest in the young-adult years and gradually wane with advancing age. Although the tendency to- ward intense emotions, impulsivity, and intensity in relationships is often lifelong, indi- sometime during the first year. During their 305 and 40s, the majority of individuals with this disorder attain greater stability in their relationships and vocational functioning. Fol- low-up studies of individuals identified through outpatient mental health clinics indicate that after about 10 years, as many as half of the individuals no longer have a pattern of be- havior that meets full criteria for borderline personality disorder.
Genetic and physiological. Borderline personality disorder is about five times more common among first-degree biological relatives of those with the disorder than in the gen- eral population. There is also an increased familial risk for substance use disorders, anti- social personality disorder, and depressive or bipolar disorders.
The pattern of behavior seen in borderline personality disorder has been identified in many settings around the world. Adolescents and young adults with identity problems (especially give the impression of borderline personality disorder. Such situations are characterized by emotional instability, ”existential” dilemmas, uncertainty, anxiety-provoking choices, con- ﬂicts about sexual orientation, and competing social pressures to decide on careers.
Borderline personality disorder is diagnosed predominantly (about 75%) in females.
Depressive and bipolar disorders. Borderline personality disorder often co-occurs with depressive or bipolar disorders, and when criteria for both are met, both may be diagnosed.
Because the cross-sectional presentation of borderline personality disorder can be mimicked by an episode of depressive or bipolar disorder, the clinician should avoid giving an addi- tional diagnosis of borderline personality disorder based only on cross-sectional presenta- tion without having documented that the pattern of behavior had an early onset and a long- standing course.