Cerebral changes and cognitive impairment after an ischemic heart disease: a multimodal MRI study

Altered functional brain networks in coronary heart disease: independent component analysis and graph theoretical analysis

Coronary heart disease (CHD) confers a high risk of cognitive and mental impairments in patients. This study aimed to explore the association of CHD with functional connectivity and topological properties of brain networks. A total of 27 patients with CHD and 44 healthy controls (HCs) participated in this study and underwent a resting-state functional magnetic resonance imaging (rs-fMRI) scan. Intra- and internetwork functional connectivity alterations were explored using independent component analysis in CHD patients. Furthermore, graph theoretical analysis was adopted to assess abnormalities in small-world properties and network efficiency metrics of brain networks. Compared to HCs, CHD patients exhibited increased functional connectivity between the posterior default mode network and posterior visual network, as well as decreased functional connectivity between the left frontoparietal network and auditory network. In terms of graph theoretical analysis, small-world network topology was identified in both CHD patients and HCs. Furthermore, the nodal local efficiency of the left putamen was significantly decreased in CHD patients compared to HCs. This study revealed alterations in brain functional connectivity and topological properties in CHD patients, shedding light on the potential neurological mechanism underlying cognitive and mental impairments in these patients and suggesting unexplored connections between CHD and higher order cognitive processing.

Aberrant Spontaneous Brain Activity in Coronary Heart Disease Using Fractional Amplitude of Low-Frequency Fluctuations: A Preliminary Resting-State Functional MRI Study

Objective

This study is aimed at exploring the spontaneous brain activity changes by measuring the fractional amplitude of low-frequency fluctuations (fALFF) and their relationship with clinical characteristics in patients with coronary heart disease (CHD).

Methods

Coronary heart disease patients (n = 25) and age, gender, and education level-matched control subjects (controls, n = 35) were included. The grey matter volume (GMV) and fALFF values were calculated to assess the difference in brain structure and function between the two groups, respectively. Correlation analyses between the fALFF values and clinical characteristics were further assessed in CHD patients. In addition, receiver operating characteristic (ROC) curves were conducted to access the diagnostic ability of the fALFF method.

Results

There was no significant difference in GMV between the CHD and control groups. Compared with the control group, patients with CHD showed significantly decreased fALFF in the left precentral/postcentral gyrus and increased fALFF in the right inferior cerebellum. Patients with a history of myocardial infarction (MI) showed significantly decreased fALFF values of the right inferior cerebellum than patients without MI. There was no significant correlation between the fALFF values in specific brain regions and disease duration. Furthermore, the ROC curves of abnormal brain regions showed the perfect accuracy of the fALFF value in distinguishing between CHD patients and controls.

Conclusion

CHD demonstrated aberrant neural activity in specific brain regions mainly related to sensorimotor networks and pain processing, which may contribute to understanding the underlying neurological mechanism of CHD.

Illuminating the Brain With X-Rays: Contributions and Future Perspectives of High-Resolution Microtomography to Neuroscience

The assessment of three-dimensional (3D) brain cytoarchitecture at a cellular resolution remains a great challenge in the field of neuroscience and constant development of imaging techniques has become crucial, particularly when it comes to offering direct and clear obtention of data from macro to nano scales. Magnetic resonance imaging (MRI) and electron or optical microscopy, although valuable, still face some issues such as the lack of contrast and extensive sample preparation protocols. In this context, x-ray microtomography (μCT) has become a promising non-destructive tool for imaging a broad range of samples, from dense materials to soft biological specimens. It is a new supplemental method to be explored for deciphering the cytoarchitecture and connectivity of the brain. This review aims to bring together published works using x-ray μCT in neurobiology in order to discuss the achievements made so far and the future of this technique for neuroscience.

Prevalence and patterns of cognitive impairment in acute coronary syndrome patients: A systematic review

BACKGROUND

Minimising risk factors through secondary prevention behaviour is challenging for patients following an acute coronary syndrome. Cognitive impairment can potentially make these changes more difficult. However, cognitive impairment prevalence in acute coronary syndrome patients is poorly understood.

DESIGN

This study was based on a systematic review.

METHODS

A systematic review was conducted of PubMed, Medline, PsycINFO and Cochrane databases up to March 2019, to identify studies reporting the prevalence of cognitive impairment in acute coronary syndrome patients. Predefined inclusion criteria were specified, including use of a validated cognitive impairment screening tool. Studies were excluded if patients had diagnosed dementia or coronary artery bypass graft surgery. Strengthening The Reporting of Observational Studies in Epidemiology and Cochrane Risk of Bias tools were used to assess quality.

RESULTS

From 747 potential studies, nine were included. The total sample size was 6457 (range 53-2174), mean age range was 51.3-77.4 years, and range of proportions of males was 57-100%. Reported cognitive impairment prevalence rates varied substantially (9-85%) with no clear pattern over time. From the two studies which examined domains, verbal fluency, memory and language were affected the most. Meta-analysis could not be undertaken due to diverse screening tools (n = 9), cut-off scores and screening timepoints.

CONCLUSIONS

Cognitive impairment in acute coronary syndrome patients is currently poorly described, and likely affects a substantial number of acute coronary syndrome patients who remain undetected and have the potential to develop to dementia in the future. As domains are most affected, this could impact understanding and retention of health education. Research is needed to accurately determine the prevalence of cognitive impairment in acute coronary syndrome patients and create suitable standardised measures and thresholds.

Neurocognitive impairment after acute coronary syndrome: Prevalence and characterization in a hospital-based cardiac rehabilitation program sample

Introduction: Prospective studies have shown the relation between acute coronary syndrome (ACS) and neurocognitive dysfunction with prevalence ranging between 10.51% and 66.8%. The present study aims to determine the prevalence level of neurocognitive dysfunction; the relations between sociodemographic, clinical and emotional variables and neurocognitive functioning in a sample of ACS patients.

Methods: The sample comprised of 53 patients engaged in cardiac rehabilitation within 3 months after an ACS. Patients with any medical history of neuropsychiatric problems prior to the ACS and illiterate subjects were not included in the study.

Results: The majority of the sample (85%) exhibits some degree of cognitive impairment, with 84.8% showing verbal fluency impairment, 60.3% memory impairment and only 26,4% had language compromised. Neurocognitive general functioning was correlated with age. Memory domain was negatively correlated with the number of daily smoked cigarettes before the ACS. Verbal fluency was influenced by schooling. Language domain was correlated with mean diastolic pressure and with the type of profession, visuospatial domain was correlated with schooling, number of cardiovascular risk factors, distress, anxiety levels and type of ACS.

Conclusion: Prevalence rate of neurocognitive dysfunction is considerably high. Besides global neurocognitive functioning, verbal fluency and memory are the most affected domains. Several variables were related to neurocognitive performance: sociodemographic; cardiovascular risk factors; clinical; psychological. The underlying mechanisms of neurocognitive dysfunction should be further explored.

Impact of cognitive performance on disease-related knowledge six months after multi-component rehabilitation in patients after an acute cardiac event

Background

Although associations between cardiovascular diseases and cognitive impairment are well known, the impact of cognitive performance on the success of patient education as a core component of cardiac rehabilitation remains insufficiently investigated so far.

Design

Prospective observational study in two inpatient cardiac rehabilitation centres between September 2014 and August 2015 with a follow-up six months after cardiac rehabilitation.

Method

At admission to and discharge from cardiac rehabilitation, the cognitive performance of 401 patients (54.5 ± 6.3 years, 80% men) following an acute coronary syndrome and/or coronary artery bypass graft was tested using the Montreal Cognitive Assessment. Patients’ disease-related knowledge was determined using a quiz (22 items for medical knowledge and 12 items for healthy lifestyle and behaviour) at both times and at follow-up. The change in knowledge after cardiac rehabilitation was analysed in multivariable regression models. Potentially influencing parameters (e.g. level of education, medication, cardiovascular risk factors, coronary artery bypass graft, comorbidities, exercise capacity) were considered.

Results

During cardiac rehabilitation, disease-related knowledge was significantly enhanced in both scales. At follow-up, the average level of medical knowledge was significantly reduced, while lifestyle knowledge remained at a stable level. The maintenance of knowledge after cardiac rehabilitation was predominantly predicted by prior knowledge, cognitive performance at discharge from cardiac rehabilitation and, in the case of medical knowledge, by coronary artery bypass graft.

Conclusion

Patient education in cardiac rehabilitation led to enhanced disease-related knowledge, but the maintenance of this essentially depended on patients’ cognitive performance, especially after coronary artery bypass graft. Therefore, patient education concepts in cardiac rehabilitation should be reconsidered and adjusted as needed.

The human cortical autonomic network and volitional exercise in health and disease

The autonomic nervous system elicits continuous beat-by-beat homeostatic adjustments to cardiovascular control. These modifications are mediated by sensory inputs (e.g., baroreceptors, metaboreceptors, pulmonary, thermoreceptors, and chemoreceptors afferents), integration at the brainstem control centres (i.e., medulla), and efferent autonomic neural outputs (e.g., spinal, preganglionic, and postganglionic pathways). However, extensive electrical stimulation and functional imaging research show that the brain's higher cortical regions (e.g., insular cortex, medial prefrontal cortex, anterior cingulate cortex) partake in homeostatic regulation of the cardiovascular system at rest and during exercise. We now appreciate that these cortical areas form a network, namely the "cortical autonomic network" (CAN), which operate as part of a larger central autonomic network comprising 2-way communication of cortical and subcortical areas to exert autonomic influence. Interestingly, differential patterns of CAN activity and ensuing cardiovascular control are present in disease states, thereby highlighting the importance of considering the role of CAN as an integral aspect of cardiovascular regulation in health and disease. This review discusses current knowledge on human cortical autonomic activation during volitional exercise, and the role of exercise training on this activation in both health and disease.