Subtle heart dysfunction detected in young adults with bipolar
In a novel study of young adults (aged 20–45) with bipolar disorder, Taiwanese researchers were able to detect subtle (subclinical) abnormalities in how their heart muscle functions and pumps blood before the onset of heart failure. The researchers’ findings, published in the journal Biological Psychiatry, point to new avenues for therapeutic development aimed at preventing progression to heart failure in an at-risk population.
Bipolar disorder is a severe mental illness that often manifests during adolescence and young adulthood. Population-based cohort studies and large-scale meta-analyses have revealed that in addition to experiencing the lifelong burden of mood symptoms, patients are at an approximately twofold-higher risk of heart failure, which is one of the main causes of premature cardiovascular mortality in patients with bipolar disorder.
Yet despite accumulating evidence that cardiovascular disease risk increases during the early stages of bipolar disorder, few studies have investigated cardiac dysfunction in the early course of the illness. The new study reveals that myocardial dysfunction is already evident in patients with bipolar disorder under 45 years of age before the onset of heart failure, suggesting a possible link to underlying coronary vascular dysfunction.
By using indicators sensitive to early detection of subclinical cardiac dysfunction before the onset of heart failure, the study showed that both global and regional peak systolic strain (measuring how much the heart muscle deforms or shortens during a contraction) and myocardial work (assessing the total work the heart muscle does to pump blood) were impaired across left ventricular segments in young adults with bipolar disorder compared to individuals of similar age without psychiatric disorders. The findings suggest an impaired cardiac function in relation to aberrant coronary vascular perfusion in the early course of bipolar disorder.
“Although there is much evidence suggesting elevated cardiovascular risk in individuals with bipolar disorder, we are still surprised by the findings that even in this young population with bipolar disorder, the myocardial dysfunction extensively involves the left ventricular segments across the perfusion territories of the three major coronary arteries,” said first author Dr Cheng-Yi Hsiao, from Taipei Medical University and Taipei Medical University Hospital.
According to lead investigator Dr Pao-Huan Chen, also from Taipei Medical University and Taipei Medical University Hospital, the hypothesis-generating study was designed to identify patterns and formulate potential hypotheses for further investigation into the heart–bipolar disorder link. The researchers believe future studies should explore the mechanistic pathways leading to coronary vascular dysfunction, in order to clarify the pathophysiology of heart failure in patients with bipolar disorder.
“Following replication in future studies across different samples, the peak systolic strain and myocardial work indices should be incorporated into the cardiovascular assessment for patients with bipolar disorder,” Chen said. “This assessment would provide an opportunity to identify and manage cardiac dysfunction as early as possible before the progression of heart failure, while laying a strong foundation for the development of new therapeutics to avoid heart failure and improve life expectancy.”
Dr John Krystal, Editor of Biological Psychiatry, said the study raises important questions about “potential genetic links between bipolar disorder and cardiac disease, the cardiac impact of psychotropic medications, and other environmental factors like diet, exercise, stress and substance use. It will also be important to understand why women were affected to a greater extent than men.”
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