BPD and Neurobiology: Does the Brain of Someone Who Suffers From BPD Differs From the Brain of a Regular Person?
Borderline personality disorder is a disorder that arguably has more stigma attached to it than any other mental health issue. Due to the media presenting BPD characters as ‘crazy’ and violent, the label is difficult to remove. This might make BPD sufferers feel like their disorder isn’t taken seriously or make them believe that all they have to do to change is to try harder. However, studies show that BPD comes with visible brain changes that explain why sufferers struggle with certain behaviours.
What Are the Symptoms of BPD?
To be diagnosed with BPD you have to struggle with at least 5 of the following 9 symptoms: frantic efforts to avoid real or perceived abandonment, a chronic feeling of emptiness, unstable self-image and sense of self, impulsive behaviour in at least two areas such as reckless driving, spending, binge eating, substance abuse and sex, inappropriate anger and difficulty controlling it, a pattern of unstable relationships with other people, recurring suicidal threats, gestures or self-harm behaviour, paranoia or dissociative symptoms and mood swings and intense emotions.
As some of the symptoms resemble complex PTSD, BPD was a disorder often seen as a result of a traumatic childhood. But now we know that BPD is a mix of environmental, anatomical and genetic factors. For example, studies indicate that the heritability of BPD in twins falls between 40% and 70%. A study conducted in 2011 that compared 542 same-sex, mostly monozygotic twins identified heritability of 60%. 
What are the Brain Differences in Someone With BPD?
Previous studies looked at brain structures to better understand the correlation between neurological changes and BPD symptoms. For example, one of the MRI studies found abnormal amygdala functioning in patients with borderline personality disorder.  Amygdala is a region of the brain involved in processing emotions and memories. Its job is also to regulate negative emotions such as fear and aggression. In the study, a group of BPD patients was asked to view negative stimuli that caused an increased amygdala activation linked to intense emotions, one of the main BPD symptoms. Other studies looking at BPD patients noted a decrease in hippocampus size that is responsible for behavioural regulation.  Individuals with smaller hippocampus are more impulsive and more susceptible to stress. In addition, Dialectical Behavioural Therapy (DBT), which is a therapy designed for BPD patients specifically, was found to decrease the heightened activity of the amygdala by helping patients develop emotion regulation strategies.  Amygdala and hippocampus are the main brain structures that explain symptoms of borderline personality disorder that can have abnormal activity and size due to genetics or trauma.