NUHS discovers novel link between unhealthy hearts and dementia

Researchers from National University Health System (NUHS) have discovered a link between cardiac diseases and brain dysfunction. The findings by a joint team of cardiovascular and brain researchers uncovered a strong association between cardiac diseases and tiny brain lesions called cerebral microinfarcts (CMIs) which are commonly found in patients with cognitive impairment or dementia.

The study is a collaboration between two research centres of NUHS, the Cardiovascular Research Institute (CVRI) and the Memory Ageing and Cognition Centre (MACC). The results were published in JAMA Neurology, a journal of the American Medical Association, and suggest that treating cardiac dysfunction could also help to prevent CMI-related brain injury. Previous studies have shown that the presence of CMIs is relatively uncommon in elderly individuals without dementia (24%), but more common in patients diagnosed with Alzheimer's disease (43%) or vascular dementia (62%).

"Our findings suggests that the development of these tiny brain lesions, which are closely linked to diseases like dementia, may be caused by chronic heart problems and vascular disease," said Associate Professor Christopher Chen, Director of MACC. CMIs were previously considered impossible to detect in living patients but the team had used higher field strength (3Tesla) magnetic resonance imaging (MRI) to identify CMIs in the brain of living persons. "In an earlier study, we showed these microinfarcts were associated with cognitive dysfunction, and now we show that they are also associated with clinical and subclinical cardiac disease," added lead author, Dr Saima Hilal, a visiting Research Fellow at the MACC and post-doctoral scientific researcher at the Erasmus Medical Center, Rotterdam, Netherlands.

The researchers studied a sample size of 243 elderly participants (average age 72 years). The presence of cortical CMIs was strongly associated not only with clinically overt cardiac disease but also with blood cardiac biomarkers. Repeat analysis after exclusion of individuals with clinically overt cardiac disease showed a correlation of the number of cortical CMIs with blood biomarkers of subclinical cardiac disease. A rise in cardiac markers was accompanied by an increased risk of developing CMIs.

"Apart from signalling problems with the heart, these cardiac biomarkers are also indicators of injury to circulatory and blood vessel systems in other organs, for example the brain. Our selected cardiac markers are powerful predictors of the presence of CMIs and cognitive impairment, and may provide scientists and clinicians with tools for the prevention or timely treatment of brain-related diseases," said Professor Arthur Mark Richards, Director of CVRI.

The success of the study leverages the cross-disciplinary research that exists in NUHS to advance cutting-edge translational biomedical research. The combination of close research collaboration between experts from different disciplines, such as the heart and brain, and access to advanced research tools like the 3Tesla MRI at the A*STAR-NUS Clinical Imaging Research Centre (CIRC) that was used in identifying CMIs, was instrumental in enabling this advance.

The researchers are looking to expand the study to gain a better understanding of the role that cardiac dysfunction plays in the development of CMIs, and if the findings are applicable to non-Asian populations who may have different risk profiles. Further studies may also determine if treatments for cerebrovascular disease-related cognitive impairment can be achieved by targeting cardiac disease.