Experts have long believed that personality disorders - types of mental illness in which people have trouble functioning with others - were relatively inflexible, and endured throughout a person’s life.

Now, new research contradicts that belief, showing that these disorders actually appear to shift over time, with many people improving at a steady rate.

Each personality disorder typically has around 8 or 9 symptoms, lead author Dr. Mark F. Lenzenweger told Reuters Health. His team found that, on average, people lose 1.4 symptoms of their personality disorders each year, or more than 5 symptoms over 4 years.

These changes occurred in both men and women, regardless of whether they were receiving treatment or had additional mental illnesses.

Consequently, after a few years, some people diagnosed with a personality disorder may no longer have one, Lenzenweger noted. For example, one woman entered the study with borderline personality disorder, and finished the study disorder-free, he said.

In an interview, Lenzenweger explained that people with personality disorders have “maladaptive personalities,” and tend to have ongoing problems in every aspect of their lives. For instance, people with narcissistic personality disorder always see themselves as entitled, believe the world revolves around them, and apply this logic at home, work and everywhere they go.

In contrast, people with depression or anxiety - not considered personality disorders - have episodes of extreme symptoms, he noted.

Despite the fact that many people with personality disorders tend to improve gradually over time, treatment is still important, Lenzenweger stressed. Not everybody included in the study experienced a decrease in symptoms - some even developed more symptoms - and people with personality disorders often need help to deal with their life and relationships, he said.

“The ‘wait and see’ attitude probably wouldn’t be good for most people,” he said.

Personality disorders are surprisingly common, with one study placing the rate as high as 13 percent of certain populations.

People with an obsessive-compulsive personality disorder, for example, may be overly rigid, tending to plan everything out and believing that everyone else should do the same. Paranoid personality disorders are ascribed to people who are generally suspicious of others and overly careful. Those with borderline personality problems, in contrast, can be excessively impulsive, and often uncertain about their decisions.

Experts have long assumed that personality disorders do not change. To investigate this assumption, Lenzenweger and his team followed 250 people with a personality disorder for 4 years, noting if their symptoms shifted. Their findings appear in the Archives of General Psychiatry.

The results show that personality disorders are “not necessarily engraved in stone, the way it’s been taught for generations,” concluded Lenzenweger, who is based at the State University of New York at Binghamton.

He said he and his colleagues plan to continue to follow study participants, and investigate further why their disorders appear to change over time.

SOURCE: Archives of General Psychiatry, October 2004.