Those afflicted with borderline personality disorder (BPD) are characterized with a variety of cognitive and emotional deficits seen throughout life regarding the regulation of emotions, impulsivity, and maladaptive images of self and others. This often leads to a pattern of unstable interpersonal relationships. Early life trauma and genetics are theorized to play major roles in the development of this condition. Up until recently, research has mostly been focused on the neurophysiological abnormalities that may play a role in the disorder, particularly in the amygdala, insula, and anterior cingulate cortex, all of which are thought to be involved in emotional and affective processing, and the regulation responses to stress.
The purpose of this post is to review a study called “Dysregulation between emotion and theory of mind networks in borderline personality disorder”. Rather than strictly look at the physiological aspects of borderline personality disorder, researchers O’Neill and colleagues instead focus on the potential social-cognitive deficits, including mentalization and theory of mind, while also observing any differences in functional connectivity within the neural networks. Mentalization refers to the process in which people internally and externally interpret the actions of themselves and others as meaningful. Theory of mind refers to the ability in which an individual is able to understand and appreciate that others have mental states that are different from their own. A deficit in either of these processes may contribute to abnormalities in behavior, and has been found in many psychiatric disorders, including borderline personality disorder. The authors describe functional connectivity as the correlation of neuronal activity within a variety of networks, throughout different regions of the brain.
In the first portion of the study researchers compared the functional connectivity of the anterior cingulate cortex and the theory of mind regions of the brain in controls and diagnosed BPD patients. The anterior cingulate cortex is known through previous research to play a crucial role in cognition and the processing of emotion and empathy, and is believed to play a role in theory of mind processing. It is hypothesized that there is a dysfunction in connectivity in BPD patients compared with controls.
The second portion of the study focused on an analysis of the default mode network in BPD patients compared with controls, which includes the medial temporal lobe, the posterior cingulate cortex, the medial, lateral, and inferior parietal cortex, the medial prefrontal cortex, and the precuneus. The default mode network is believed to play a role in numerous internal cognitive processes such as self-referential processing, episodic memory, theory of mind processing, emotion, and inner speech. According to the authors, there seems to be a gap in research regarding abnormalities in the default mode network in patients with BPD, and hypothesize that differences in functional activity may be found to be a useful biological marker for the disorder in the future.
Due to the fact that the nearly 75% of individuals diagnosed with borderline personality disorder are women, the researchers decided only to include females in the participant group; this was to avoid any potential skewing of results due to gender-based differences. Ethics committees from the Adelaide and Meath Hospital and St. James’s Hospital in Dublin, Ireland gave ethical approval to conduct the study. Twenty two subjects, all of whom were diagnosed with BPD and receiving treatment in Dublin from the South-West mental health services, volunteered for the study. A second psychiatrist was tasked to confirm the original diagnosis of BPD of all subjects before inclusion in the study. Controls were matched with subjects for age, and nineteen female volunteers were recruited from the same community in which the subjects resided. Psychiatrists screened the subjects and controls to ensure there was no history of substance abuse, neurological trauma, or psychiatric conditions, all of which were disqualifying factors. History of major depressive disorder was the only exception to this rule, and current treatment was not a disqualifying factor for the participants. Rating scales used for this purpose included the SCID-I, the Hamilton Rating Scale for Depression, the Eysenck Personality Questionnaire, the Barratt Impulsiveness Scale, and the Beck Depression Inventory. Of the BPD patients whose data was analyzed, twelve were taking SSRI or dual acting-antidepressants at the time the study was conducted. Three of those twelve were also taking quetiapine, and one was taking olanzapine.
During the fMRI task, participants were instructed to choose whether or not the observed stimuli was either “understood” or “not understood”. Stimuli consisted of cartoons that displayed a variety of visual puns or jokes that required mentalization. A control condition was also displayed, which included cartoons that were ambiguous and contained some degree of incongruity. All slides were displayed for six seconds, and had been previously validated in previous studies; they contained no aggressive, violent, or sexual content. Rest events were randomly placed between trials, in which participants were shown a blank screen. All data in which the participant responded in time, regardless of the answer that was given, was included in analysis. Each participant went through 120 trials, and completion of the entire task took roughly 18 minutes.
Two of the BPD patients did not complete the assessment sessions, and three were excluded from the fMRI analysis because of excessive head movement during the session, leaving seventeen BPD patients and nineteen controls for final fMRI analysis. Sophisticated software was used to preprocess the data, including SPM8 and CONN. These tools were used to compensate for the slight variations in recorded data due to movement or slice-dependent time shifts. Also, spurious data was removed from analysis; including any recorded signal that came from within the white matter, or cerebrospinal fluid. An alpha level of .025 was used during the preprocessing stage to compensate for the two different networks that were analyzed. It is important to note that the use of medication was also included as a factor in analysis, but did not affect any of the final results.
According to the Barratt Impulsiveness Scale, those with BPD scored significantly higher on impulsivity and neuroticism, and lower on extraversion, compared to controls. Fewer patients with BPD had continued education past high school and consumed many more cigarettes than controls. In the theory of mind condition, BPD subjects were less likely to respond “understood” when having to choose between positive or negative responses, leading the researchers to believe that they may have been unsure when observing interpersonal content. Across all conditions, those with BPD also took longer to deliver positive responses compared to the control group.
In controls, increased functional connectivity was observed between the precuneus, the left inferior frontal gyrus, the left precentral frontal, and the left middle occipital parietal, compared to BPD subjects. Furthermore, decreased functional connectivity was found in the BPD subjects between the anterior cingulate cortex and the left superior temporal cortex, the right mid-cingulate cortex, and the right supramarginal parietal. The right mid-cingulate cortex is known to play a role in self- and other- perspectives. The superior temporal cortex and the right supramarginal parietal, together make up the temporo-parietal junction, which happens to belong to the main neural network responsible for mentalization. According to the researchers, these findings indicate a disconnect between the affective brain region, and the theory of mind neural network, causing dysfunction in theory of mind processing originating from emotional the emotional regions.
Further, individuals with borderline personality disorder showed higher functional connectivity to the left mid-frontal, left precentral, left mid-occipital parietal, and Brodmann areas 44 and 45, both of which make up Broca’s area. The researchers have hypothesized that the increased activity between these regions may help explain the high rates of internal thought and self-referential processing that is often observed in patients with BPD, although this theory is premature and should be further tested in future studies.
Several limitations to this study were acknowledged by the researchers, one of which includes the fact that functional magnetic resonance imaging strictly measures BOLD, which stands for the blood level oxygenation dependent signal; meaning that it does not directly measure neuronal activity, it has only been assumed that increased blood flow to a specific area of the brain is due to increased activity. Another limitation is that subject participation was limited only to those with BPD and no other comorbid conditions, the exception being major depressive disorder. There is a high rate of comorbidity in the population of people with borderline personality disorder; according to the authors, exclusion of these individuals may have limited the generalisability of the results. Aside from the DSM-IV criteria, no other measures were used during the study to confirm BPD or other psychiatric illness; this may be viewed as another limitation.
Further research investigating the findings of this study should include BPD patients with a more natural variety of comorbid disorders; similar results will strengthen the findings of this study. Also, further research should be conducted on the differences between resting state connectivity of BPD and other psychiatric conditions. Borderline personality disorder is not the only condition that has been linked with higher resting state functional connectivity, and it would be interesting to determine whether or not there are any similarities in dysfunctional neural networks in BPD compared to other psychological conditions. Just as it has been demonstrated in our previous posts exploring psychopathy and bipolar disorders, this study shows functional and physical changes in those with borderline personality disorder. Mental illness arguably robs the individual of free will, and this should always be taken into consideration in the criminal justice system when handling cases involving mentally ill defendants.
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