They have the thinnest skin, the shortest fuses and take the hardest knocks. In psychiatrists' offices, they have long been viewed as among the most challenging patients to treat.

They are the kind of people who drive a friend away for interfering and subsequently berate that friend for abandonment.

But almost 20 years after the designation of borderline personality disorder as a recognized mental health condition, some understanding and hope have surfaced for people with the condition and their families.

Borderline personality disorder was center stage in May at the annual meeting of the American Psychiatric Assn. -- with multiple sessions and speakers devoted to the topic. And the message from the meeting was clear: After years during which they threw up their hands, leaders in psychiatry now want to convey a more positive message about the condition and what can be done to help those who have it.

"Borderline personality disorder is considered a pejorative term," says Dr. Richard G. Hersh, a psychiatrist at Columbia University's College of Physicians and Surgeons. "But there are new treatments and new data that give reason for optimism."

That is especially significant given results of a survey of more than 24,000 adults, conducted by the federal government and released last year, that found a lifetime prevalence of borderline personality disorder to be almost 6% -- more than double previous estimates.

"The public and patients want to learn more about this condition, and more doctors want to treat it," says Valerie Porr, founder of a national advocacy group called TARA, Association for Personality Disorders.

Messy relationships

"You look back now and see things," says Patricia Green, the mother of a 25-year-old woman diagnosed with borderline personality disorder.

As a child, Sooki (a pseudonym) was sensitive and easily rattled. In high school, she had such difficulty making friends that she opted for home schooling.

After high school, the real trouble began. She had a series of turbulent relationships; was fired from jobs and racked up serious credit card debt. She began cutting herself and was diagnosed with depression.

Patricia, a school nurse in San Diego, attended a workshop on borderline personality disorder six years ago and left suspecting her daughter had it. The description seemed to fit Sooki to a T.

"Suddenly, all the things about Sooki that didn't seem to be related were all under one umbrella," Patricia says.

As in the case of Sooki, people with the disorder make a mess of their relationships -- and no wonder, given the hallmark symptoms: mood instability, fear of abandonment, impulsive behavior, anger and suicidal or self-injurious acts. People with the disorder may misperceive the actions -- even the facial expressions -- of others.

"You can't regulate your emotions despite your best efforts," says Marsha Linehan, a University of Washington psychologist and leading expert on the disorder.

Borderline personality disorder occurs equally as often in men and women and sufferers often also have other mental illnesses or substance abuse problems. The composite of an angry, unstable, clingy, substance abuser is not a pretty one, and people with the disorder suffer greatly because they drive away even the people who love them most, experts say.

"Having a relative with BPD can be hell," says Perry D. Hoffman, president of the National Education Alliance for BPD. "But our message to families is to please stay the course with your relative because it's crucial to their well being."

One of the most significant developments for those affected by the disorder has been the emergence of a strong family and patient advocacy movement pressing for more research and establishing support networks and treatment referral services. Porr started TARA in 1995; Hoffman launched her organization in 2001. In 2007, the National Alliance for the Mentally Ill, a patient advocacy group, put borderline personality disorder on its list of "priority populations" for public policy efforts.

The National Institute of Mental Health, along with the nonprofit advocacy groups and major medical institutions such as UCLA and the Mount Sinai School of Medicine in New York have convened national and regional conferences on the disorder.