Borderline personality disorder is actually a brain disorder. Brain imaging completely changes the way we think about personality. It is easy to label people as bad, willful, uncaring, or even possessed. And diagnosing someone with a personality disorder, such as BPD, suggests their personality or character is a problem. But what is the organ of personality? It’s the brain. If someone has an unstable personality, it is most likely related to imbalances in their brain. People with BPD may have abnormal activity in areas of the brain that regulate emotion, fear, and impulse control. Our brain-imaging work has also taught us that many environmental factors can adversely impact brain function and lead to symptoms of mental illness. We have seen how environmental toxins (such as toxic mold), infections like Lyme disease, extremely low thyroid, anemia, anoxia (a lack of oxygen), carbon monoxide poisoning, brain injury (especially to the frontal lobes), and even chemotherapy can alter brain ...