Normalizing activation levels
Both treatments were associated with convergent activity increases and decreases in several brain regions: the anterior cingulate cortex, medial frontal gyrus, inferior frontal gyrus, cingulate gyrus, parahippocampal gyrus, and the posterior cingulate cortex.
The researchers then examined studies based on treatment method – psychotherapy or pharmacotherapy and the effect on the two disorders.
“After psychotherapy, the frontal lobe and temporal lobe were the primary brain regions in which activation changed, indicating a top-down effect of this therapy type, while after drug therapy, the limbic area was the region in which activation changed, indicating a ‘bottom-up’ effect,” said Dr. Li.
Dr. Li cited previous research pointing to functional and structural abnormalities in both disorders – especially in the default mode network (DMN) and frontolimbic network.
In particular, alterations in the amygdala and the parahippocampal gyrus are reported more frequently in BPD than in BD, whereas dysfunctional frontolimbic brain regions seem to underlie the emotional dysfunction in BPD. Several studies have also associated the impulsivity of BD with dysfunctions in the interplay of cortical-limbic circuits.
Dr. Li said the study findings suggest “that treatment may change these brain activation levels by acting on the abnormal brain circuit, such as the DMN and the frontolimbic network so as to ‘normalize’ its activity and improve symptoms.”
Specifically, brain regions with abnormally increased activation “showed decreased activation after treatment, and brain regions with abnormally decreased activation showed increased activation after treatment.”
Discrete, overlapping mechanisms
Commenting on the study, Roger S. McIntyre, MD, professor of psychiatry and pharmacology, University of Toronto, and head of the Mood Disorders Psychopharmacology Unit, said the study “provides additional support for the underlying neurobiological signature of bipolar disorder and a commonly encountered co-occurring condition – borderline personality disorder – having both discrete yet overlapping mechanisms.”
Dr. Roger S. McIntyre
He found it interesting that “medications have a different principal target than psychosocial interventions, which has both academic and clinical implications.
“The academic implication is that we have reasons to believe that we will be in a position to parse the neurobiology of bipolar disorder or borderline personality disorder when we take an approach that isolates specific domains of psychopathology, which is what they [the authors] appear to be doing,” said Dr. McIntyre, who wasn’t associated with this research.
In addition, “from the clinical perspective, this provides a rationale for why we should be integrating pharmacotherapy with psychotherapy in people who have comorbid conditions like borderline personality disorder, which affects 20% of people living with bipolar disorder and 60% to 70% have borderline traits,” he added.
The research was supported by the Anhui Natural Science Foundation and Grants for Scientific Research from Anhui Medical University. Dr. Li and coauthors declared no relevant financial relationships. Dr. McIntyre has received research grant support from CIHR/GACD/National Natural Science Foundation of China and the Milken Institute; speaker/consultation fees from Lundbeck, Janssen, Alkermes, Neumora Therapeutics, Boehringer Ingelheim, Sage, Biogen, Mitsubishi Tanabe, Purdue, Pfizer, Otsuka, Takeda, Neurocrine, Sunovion, Bausch Health, Axsome, Novo Nordisk, Kris, Sanofi, Eisai, Intra-Cellular, NewBridge Pharmaceuticals, Viatris, AbbVie, Atai Life Sciences. Dr. McIntyre is a CEO of Braxia Scientific Corp.
A version of this article first appeared on Medscape.com.