In an experimental medicine study of D-cycloserine given during chronic obstructive pulmonary disease (COPD) rehabilitation, only models including brain imaging markers of breathlessness-expectation successfully predicted Dyspnea-12 score improvement. D-cycloserine was independently associated with breathlessness improvement, according to original research published in Thorax.
Chronic breathlessness persisting despite maximal medical therapy is a key feature of COPD. While pulmonary rehabilitation is the best treatment for chronic breathlessness in COPD, responses to treatment are variable, with 30% deriving no clinical benefit, Sarah L. Finnegan, PhD, with the Nuffield Department of Clinical Neurosciences, University of Oxford (England), and colleagues wrote.
While recent research has shown fear and anxiety to be key components of the expectation that plays an important role in the mechanisms and maintenance of breathlessness, expectation-related effects have not previously been considered in prediction studies of pulmonary rehabilitation outcomes. The authors’ prior research showed a clear correlation between improvements in breathlessness through pulmonary rehabilitation and expectation-related brain activity in areas that include the anterior insula, anterior cingulate cortex, and prefrontal cortex. That research methodology, however, did not attempt to predict individual responses.
The current study focused on brain activity changes within preselected regions associated with breathlessness-expectation and body and symptom perception. Its purpose was to predict improvements in breathlessness during pulmonary rehabilitation by analyzing baseline data from a longitudinal experimental medicine study of D-cycloserine on breathlessness during pulmonary rehabilitation. D-cycloserine, a partial agonist of brain N-methyl-D-aspartate receptors, was chosen because of its effects on neural plasticity and influence on brain expectation mechanisms associated with cognitive behavioral therapies. The authors hypothesized that baseline brain activity in response to breathlessness-related expectation would predict improvement in breathlessness through pulmonary rehabilitation, with D-cycloserine emerging as a significant factor in the prediction model.
The researchers recruited 71 participants (18 women, median age 71 years [46-85 years]) with mild to moderate COPD immediately prior to enrollment in a National Health Service–prescribed course of pulmonary rehabilitation. They were randomized double-blind to receive either 250 mg oral D-cycloserine or a matched placebo. Participants received a single dose on four occasions 30 minutes prior to the onset of the first four pulmonary rehabilitation sessions.
Baseline variables, including brain-activity, self-report questionnaires responses, clinical measures of respiratory function, and drug allocation were used to train three machine-learning models to predict the outcome, a minimally clinically relevant change in the Dyspnea-12 score.
Improvements in Dyspnea-12 score occurred only in the two models including brain imaging markers of breathlessness-expectation (sensitivity 0.88, specificity 0.77). The model that combined brain and behavior metrics produced the best classification performance (accuracy, 0.83 [95% confidence interval, 0.75-0.90]; sensitivity, 0.88; specificity, 0.77; P < 0.001). While the brain-only model was able to correctly categorize participants with statistically significant likelihood (accuracy, 0.70 [95% CI, 0.58-0.81]), it demonstrated poor goodness of fit, a measure of how well sample data fit a distribution from a population with a normal distribution. “By enriching the brain-only models with questionnaires and physiology measures improved performance considerably,” the researchers stated.
“Our findings demonstrate the first predictive model of change in breathlessness across pulmonary rehabilitation and, for the first time, the clinical relevance of expectation-related brain activity as a therapeutic target in the treatment of breathlessness. ... This was achieved using sensitive brain imaging techniques in order to capture personalized responses to breathlessness-expectation which has, until recently remained relatively unexplored.”
“This study raises interesting questions about breathlessness-expectations,” commented assistant professor of medicine Mary Jo S. Farmer, MD, PhD, director pulmonary hypertension service, University of Massachusetts, Worcester, in an interview. “There is much more to be understood about expectations pathways as to how these pathways are built upon prior experience and pave the way for reaction to future experiences. There is need for a similar study with larger sample size and clarification of the role of the effect of the agent D-cycloserine on breathlessness-expectation.”
The researchers noted their study’s limitations, pointing out that the small sample size precluded holding out a proportion of the original data to create an external validation dataset.
Dr. Finnegan and Dr. Farmer declared no disclosures relevant to this study. This work was supported by the JABBS Foundation and Dunhill Medical Trust. This research was funded in whole, or in part, by the Wellcome Trust.