Borderline personality disorder (BPD) is a serious mental condition defined by extremes in behavior. The name itself is derived from the alleged borderline between neurosis and psychosis, although modern psychologists have backed away from that definition. In essence, a borderline personality disorder patient is always teetering on the edge between manageable anxiety and uncontrollable psychotic behavior. A patient may cut himself with a knife, for example, but only to the point of self-mutilation, not necessarily suicide.

Although borderline personality disorder can manifest itself in males or females, the majority of diagnosed cases tend to be young women just entering adulthood. It is believed that childhood trauma or sexual abuse is directly linked to the later formation of borderline personality disorder. Sufferers often enter into risky sexual relationships or develop intense but unstable friendships. Those with true borderline personality disorder may become so emotionally dependent on others that steady relationships become impossible to maintain.

One major aspect of borderline personality disorder is the 'black or white' worldview. Those with BPD tend to evaluate their friends, co-workers and family members with a hypercritical eye. A sibling may be seen as an idealized role model one day, only to be treated as untrustworthy or useless the next. The only person a BPD sufferer hates more than an unfaithful friend is his or herself. Self-mutilations and extremely low self-esteem are classic symptoms of the disorder.

There are some critics who suggest that borderline personality disorder is more of a generic diagnosis used to categorize those who don't fit other mental disorder definitions neatly. BPD may be similar to the muscular condition of fibromyalgia -- more of a catch-all diagnosis for a number of unrelated symptoms. In fact, many young women in the 1960s and 1970s were routinely diagnosed with borderline personality disorder, leading to controversial confinement in psychiatric hospitals. Winona Ryder's character in the film Girl, Interrupted is diagnosed with borderline personality disorder, although she does not manifest the more extreme symptoms.

Treatment for borderline personality disorder is typically long-term psychotherapy and the use of mood stabilizing drugs such as Prozac. Psychotherapy for BPD patients is not always an easy process, because sufferers often treat their doctors with the same disdain and animosity they show to others. The main objective of psychotherapy is to get past the patient's defense mechanisms and discover the initial trauma which triggered the condition. Borderline personality disorder can be equally devastating for close friends and family members, who feel the need to 'clean up' after the sufferer and may become enablers.

Borderline personality disorder can accompany other mental conditions, which often makes a proper diagnosis difficult. While someone with a bipolar disorder may be depressed for weeks, a BPD sufferer may be depressed for a few hours and then become almost manic for a short time. Binge eating, promiscuity, gambling and excessive shopping are also indicators of an active borderline personality disorder.