Borderline personality disorder (BPD) is a mental health condition characterised by symptoms such as mood instability, heightened impulsivity, and impaired self-awareness. Collectively, these symptoms can severely hinder an individual’s ability to engage meaningfully in various aspects of their life. Historically, doctors and mental health researchers had an incomplete understanding of the brain processes leading to the onset of BPD. However, new information helps clarify this understanding by highlighting two fundamental brain effects associated with the disorder.
Understanding Borderline Personality Disorder
Mental health professionals define a personality disorder as any psychiatric or psychological condition that impairs an individual’s ability to understand or effectively participate in interpersonal relationships or social interactions. It also affects one’s ability to maintain a stable self-image independent of relationships with others. Generally, the impairments seen in personality disorders manifest as consistently recurring patterns of thought or behaviour that deviate from social norms, creating a sense of separation between the individual and their social or personal environment. The American Psychiatric Association, which establishes standard mental health guidelines in the United States, recognises BPD and several other personality disorders as distinct categories of mental illness.
To be diagnosed with BPD, an individual must exhibit five or more symptoms specifically associated with the condition. These symptoms include angry outbursts without relevant social context, a destabilising tendency to categorise relationships as strictly “good” or “bad,” unpredictable mood swings that include depression, recurrent involvement in impulsive or reckless behaviour, frequent expressions of boredom, making suicidal threats, and engaging in various forms of purposeful, non-fatal self-injury. Some individuals with BPD may eventually commit suicide. Although many people develop BPD symptoms during childhood or adolescence, current guidelines restrict official diagnosis of the condition (or any other personality disorder) to adults, except in relatively rare circumstances.
Brain Function Basics
The brain’s primary functions are conducted through specialised nerve cells called neurons. With the assistance of chemicals known as neurotransmitters, these neurons engage in a constant, dynamic “conversation” that determines brain function in any given set of circumstances. Although all neurons operate on the same fundamental principles, specific types of neurons perform particular tasks in designated brain areas. In the context of BPD, two particularly important brain areas are the limbic system and the frontal cortex. Neuron activity in the limbic system helps determine a person’s basic emotional state, while neuron activity in the frontal cortex helps regulate mood stability by controlling emotional fluctuations.
Changes Associated with BPD
In a study review in the journal Biological Psychiatry, a team of researchers from the University of Toronto compiled data from 11 different studies that used modern brain imaging technology to examine neuron changes in people with BPD. The researchers concluded that individuals with BPD experience two distinct alterations in neuron function. Firstly, the neurons in the limbic system, which play a role in determining a person’s emotional state, show heightened levels of activity, resulting in a markedly negative mood. Additionally, the neurons in the frontal cortex, which help regulate mood fluctuations, show decreased activity levels. Without the regulatory actions typically provided by the frontal cortex, negative moods generated in the limbic system become abnormally persistent and intense.
Similar types of brain destabilisation occur in individuals with other personality disorders and various other mental illnesses. However, the study authors note that individuals with BPD experience changes in a specific part of the frontal cortex, known as the subgenual anterior cingulate, which appears to be a unique and identifying characteristic of the disorder. They also emphasise that although people with BPD have turbulent emotional lives, the effects of the disorder can be managed with psychotherapy that enhances the frontal cortex’s ability to regulate emotional fluctuations. The most successful therapies for BPD already significantly achieve these improvements.
