New York, Aug 29 (IANS): People with a mental illness marked by unstable moods often experience trouble having successful friendships and romantic relationships, a study says.

Individuals with the illness borderline personality disorder, or BPD may have lowered brain activity in regions important for empathy which in turn could trigger trouble in relationships, the study indicated.

"Our results showed that people with BPD traits had reduced activity in brain regions that support empathy," said study lead author Brian Haas, assistant professor at University of Georgia in the US.

"This reduced activation may suggest that people with more BPD traits have a more difficult time understanding and/or predicting how others feel, at least compared to individuals with fewer BPD traits," Haas noted.

For the study, the researchers used functional magnetic resonance (fMRI) imaging to measure brain activity in 80 participnats.

They found a link between those with high borderline personality traits and a decreased use of neural activity in two parts of the brain: the temporoparietal junction and the superior temporal sulcus, two brain regions implicated to be critically important during empathic processing.

"We found that for those with more BPD traits, empathetic processes are not as easily activated," study co-author Joshua Miller, psychology professor at University of Georgia noted.

"Borderline personality disorder is considered one of the most severe and troubling personality disorders," Miller said.

"BPD can make it difficult to have successful friendships and romantic relationships. These findings could help explain why that is," Miller pointed out.

The findings were published in the journal Personality Disorders: Theory, Research and Treatment.