Fronto-temporal functional disconnection precedes hippocampal atrophy in clinically confirmed multi-domain amnestic Mild Cognitive Impairment.

Mild Cognitive Impairment (MCI) is fraught with high false positive diagnostic errors. The high rate of false positive diagnosis hampers attempts to identify reliable and valid biomarkers for MCI. Recent research suggests that aberrant functional neurocircuitries emerge prior to significant cognitive deficits. The aim of the present study was to examine this in clinically confirmed multi-domain amnestic-MCI (mdaMCI) using an established, multi-time point, methodology for minimizing false positive diagnosis. Structural and resting-state functional MRI data were acquired in healthy controls (HC, n=24), clinically-confirmed multi-domain amnestic-MCI (mdaMCI, n=14) and mild Alzheimer's Dementia (mAD, n=6). Group differences in cortical thickness, hippocampal volume and functional connectivity were investigated. Hippocampal subvolumes differentiated mAD from HC and mdaMCI. Functional decoupling of fronto-temporal networks implicated in memory and executive function differentiated HC and mdaMCI. Decreased functional connectivity in these networks was associated with poorer cognitive performance scores. Preliminary findings suggest the large-scale decoupling of fronto-temporal networks associated with cognitive decline precedes measurable structural neurodegeneration in clinically confirmed MCI and may represent a potential biomarker for disease progression.

Oral pre-treatment with thiocyanate (SCN-) protects against myocardial ischaemia-reperfusion injury in rats.

Despite improvements in revascularization after a myocardial infarction, coronary disease remains a major contributor to global mortality. Neutrophil infiltration and activation contributes to tissue damage, via the release of myeloperoxidase (MPO) and formation of the damaging oxidant hypochlorous acid. We hypothesized that elevation of thiocyanate ions (SCN-), a competitive MPO substrate, would modulate tissue damage. Oral dosing of rats with SCN-, before acute ischemia-reperfusion injury (30 min occlusion, 24 h or 4 week recovery), significantly reduced the infarct size as a percentage of the total reperfused area (54% versus 74%), and increased the salvageable area (46% versus 26%) as determined by MRI imaging. No difference was observed in fractional shortening, but supplementation resulted in both left-ventricle end diastolic and left-ventricle end systolic areas returning to control levels, as determined by echocardiography. Supplementation also decreased antibody recognition of HOCl-damaged myocardial proteins. SCN- supplementation did not modulate serum markers of damage/inflammation (ANP, BNP, galectin-3, CRP), but returned metabolomic abnormalities (reductions in histidine, creatine and leucine by 0.83-, 0.84- and 0.89-fold, respectively), determined by NMR, to control levels. These data indicate that elevated levels of the MPO substrate SCN-, which can be readily modulated by dietary means, can protect against acute ischemia-reperfusion injury.

Association between lifetime depression history, hippocampal volume and memory in non-amnestic mild cognitive impairment.

Hippocampal subfield volume loss in older adults with amnestic mild cognitive impairment (aMCI) and depression history are associated with amyloid beta and tau pathology, thereby increasing the risk for Alzheimer's disease (AD). However, no studies have exclusively examined distinct alterations in hippocampal subfields in non-amnestic MCI (naMCI) in relation to depression history. Here, we used both longitudinal and transverse hippocampal segmentation methods using the automated FreeSurfer software to examine whether a lifetime depression history is associated with differences in hippocampal head/body/tail (H/B/T) and key subfield volumes (CA1, subiculum, dentate gyrus) in older adults with naMCI. Further, we explored whether differences in hippocampal H/B/T and subfield volumes were associated with structured and unstructured verbal encoding and retention, comparing those with and without a depression history. The naMCI with a depression history group demonstrated larger or relatively preserved right CA1 volumes, which were associated with better unstructured verbal encoding and as well as structured verbal memory retention. This association between memory encoding and hippocampal CA1 and total head volume was significantly different to those with no depression history. The relationship between right CA1 volume and memory retention was also moderated by depression history status F (5,143) = 7.84, p < 0.001, R2  = 0.22. Those participants taking antidepressants had significantly larger hippocampal subiculum (p = 0.008), and right hippocampal body (p = 0.004) and better performance on structured encoding (p = 0.011) and unstructured memory retention (p = 0.009). These findings highlight the importance of lifetime depression history and antidepressant use on the hippocampus and encoding and memory retention in naMCI.

The Cyberbullying Picture Series (CyPicS): Developed for Use in Cyberbullying and Cyberbystander Research.

While research has examined bystander responses in a traditional sense, there is a dearth of research regarding responses of cyberbystanders in a real-time situation, such as observing a cyberbullying scenario. This article describes a novel protocol designed to develop a series of images to be used to undertake research that aims to examine cyberbystander responses. A total of 24 scenarios (12 negative (cyberbullying) and 12 neutral) were created by the researchers and designed to mimic the way such scenarios would appear on a social networking site. The negative (cyberbullying) stimuli were rated in terms of level of severity, and the scenarios were compared to a selection of images from the International Affective Picture System using the Self-Assessment Manikin. These stimuli were compiled to form the Cyberbullying Picture Series (CyPicS). Through the development of the CyPicS, this protocol will aid future researchers in examining responses to real-life scenarios, as it is the first of its kind to develop these scenarios and test and evaluate them. CyPicS will provide researchers with the means to systematically evaluate responses to validated, real-life cyberbullying scenarios. More specifically, future researchers can utilize CyPicS to investigate how cyberbystanders respond when observing cyberbullying stimuli compared to neutral stimuli, as well as to measure and understand reactions or perceptions of cyberbullying. CyPicS can be used in any form of cyberbullying research (including electroencephalography and eye-tracking studies, psychological research, and functional magnetic resonance imaging studies) that may utilize bystander reactions and behaviors. Findings from research that utilizes CyPicS will greatly increase our understanding of bystander responses, and with variations in study design, researchers can further examine past or future associations with cyber-victim/bully status and mental health outcomes.

Investigating the association between sleep quality and diffusion-derived structural integrity of white matter in early adolescence.

INTRODUCTION: Poor sleep quality has been linked to reduced neural connectivity through decreased white matter (WM) structural integrity. WM tract development has been shown to continue throughout adolescence with studies reporting positive correlations between diffusion-derived estimates of structural integrity and reduced sleep quality in adult samples. Few studies have investigated this relationship exclusively within a sample of young adolescents. METHODS: N = 51 participants aged 12 years (M = 151.5 months, SD = 4 months) completed a self-report questionnaire which included the Pittsburgh Sleep Quality Index (PSQI) and underwent Diffusion Tensor Imaging (DTI) as part of their baseline assessment in the Longitudinal Adolescent Brain Study (LABS) being undertaken in Queensland, Australia. Fractional anisotropy (FA) were extracted using Tract-Based Spatial Statistics (TBSS) to investigate associations between sleep quality and WM integrity across the brain. RESULTS: Significant correlations were found between the posterior limb of the internal capsule and the PSQI total sleep quality and sleep latency scores. There was also a significant difference in sleep duration between male and female participants. CONCLUSION: These findings provide an important insight of the impact that sleep may have on early adolescent WM development. Ongoing longitudinal assessment of sleep on WM development across adolescence is likely to provide further important information about how WM maturation relates to variations in sleep quality as circadian rhythm changes occur during middle and late adolescence.

Using measures of intrinsic homeostasis and extrinsic modulation to evaluate mental health in adolescents: Preliminary results from the longitudinal adolescent brain study (LABS).

Adolescence is a period when complex interactions occur between mental health risk factors. The Longitudinal Adolescent Brain Study (LABS) commenced in 2018, to monitor environmental and psychosocial factors thought to influence mental health in 500 young people. Participants commence at 12 years of age, via a community-based recruitment model, and data is collected at 15 time-points over five years. This study examines demographic and psychosocial self-report data from time-point 1, for the first 50 participants. Here we investigate associations between environmental and psychosocial factors, considered as measures of intrinsic homeostasis and extrinsic modulation. Numerous strong correlations were found. Findings indicate that sleep dysfunction and social connectedness were strongly associated external modulators of intrinsic homeostasis in this sample of 12-year old participants. To successfully address the increase in mental health problems in young people, comprehensive evaluation of lifestyle and environmental risk factors is recommended in addition to medicalised approaches. Interventions to promote mental health wellbeing in young adolescents should include a focus on sleep quality and patterns and the positive and negative aspects of social connectedness.

Hippocampal plasticity underpins long-term cognitive gains from resistance exercise in MCI.

Dementia affects 47 million individuals worldwide, and assuming the status quo is projected to rise to 150 million by 2050. Prevention of age-related cognitive impairment in older persons with lifestyle interventions continues to garner evidence but whether this can combat underlying neurodegeneration is unknown. The Study of Mental Activity and Resistance Training (SMART) trial has previously reported within-training findings; the aim of this study was to investigate the long-term neurostructural and cognitive impact of resistance exercise in Mild Cognitive Impairment (MCI). For the first time we show that hippocampal subareas particularly susceptible to volume loss in Alzheimer's disease (AD) are protected by resistance exercise for up to one year after training. One hundred MCI participants were randomised to one of four training groups: (1) Combined high intensity progressive resistance and computerised cognitive training (PRT+CCT), (2) PRT+Sham CCT, (3) CCT+Sham PRT, (4) Sham physical+sham cognitive training (SHAM+SHAM). Physical, neuropsychological and MRI assessments were carried out at baseline, 6 months (directly after training) and 18 months from baseline (12 months after intervention cessation). Here we report neuro-structural and functional changes over the 18-month trial period and the association with global cognitive and executive function measures. PRT but not CCT or PRT+CCT led to global long-term cognitive improvements above SHAM intervention at 18-month follow-up. Furthermore, hippocampal subfields susceptible to atrophy in AD were protected by PRT revealing an elimination of long-term atrophy in the left subiculum, and attenuation of atrophy in left CA1 and dentate gyrus when compared to SHAM+SHAM (p = 0.023, p = 0.020 and p = 0.027). These neuroprotective effects mediated a significant portion of long-term cognitive benefits. By contrast, within-training posterior cingulate plasticity decayed after training cessation and was unrelated to long term cognitive benefits. Neither general physical activity levels nor fitness change over the 18-month period mediated hippocampal trajectory, demonstrating that enduring hippocampal subfield plasticity is not a simple reflection of post-training changes in fitness or physical activity participation. Notably, resting-state fMRI analysis revealed that both the hippocampus and posterior cingulate participate in a functional network that continued to be upregulated following intervention cessation. Multiple structural mechanisms may contribute to the long-term global cognitive benefit of resistance exercise, developing along different time courses but functionally linked. For the first time we show that 6 months of high intensity resistance exercise is capable of not only promoting better cognition in those with MCI, but also protecting AD-vulnerable hippocampal subfields from degeneration for at least 12 months post-intervention. These findings emphasise the therapeutic potential of resistance exercise; however, future work will need to establish just how long-lived these outcomes are and whether they are sufficient to delay dementia.

Associations between Facial Emotion Recognition and Mental Health in Early Adolescence.

Research shows that adolescents with mental illnesses have a bias for processing negative facial emotions, and this may play a role in impaired social functioning that often co-exists with a mental health diagnosis. This study examined associations between psychological and somatic problems and facial emotion recognition in early adolescence; as any processing biases in this age-group may be an early indicator of later mental illnesses. A community sample of 40 12-year-olds self-rated their symptoms of anxiety, depression, and somatization via two mental health screeners. They also completed a computerized emotion recognition task in which they identified photographs of 40 faces showing expressions of anger, fear, sadness, happiness, or neutral expression. Results showed that increased symptoms of anxiety, depression, and somatization were significantly associated with fewer correct responses to angry expressions. These symptoms were also associated with faster and more accurate recognition of fearful expressions. However, there was no association between mental health and recognition of sad affect. Finally, increased psychological and/or somatic symptomology was also associated with better identification of neutral expressions. In conclusion, youth with increased psychological and/or somatic problems exhibited a processing bias for negative anger and fear expressions, but not sadness. They showed better processing of neutral faces than youth with fewer psychological and/or somatic problems. Findings are discussed in relation to indicators of mental illnesses in early adolescence and the potential underpinning neural mechanisms associated with mental health and emotional facial recognition.

Neurobiological underpinnings of cyberbullying: A pilot functional magnetic resonance imaging study.

There is a dearth of research that has investigated the neural correlates of cyberbullying, using task-based functional magnetic resonance imaging (fMRI) and, specifically, in a real-time context such as observing cyberbullying scenarios. This article presents pilot data from a novel protocol designed to undertake such research with the overall aim being to elucidate the neurobiological underpinnings of cyberbullying via task-based fMRI (tb-fMRI)) in passive cyberbystanders. Young adults (N = 32, 18 to 25 years old) viewed six negative (cyberbullying) and six neutral stimuli from the Cyberbullying Picture Series (CyPicS) while undergoing tb-fMRI. Our results revealed 12 clusters of significantly greater blood-oxygenation-level-dependent (BOLD) responses (family wise error corrected p FWE < .05) in participants when viewing cyberbullying stimuli compared to neutral stimuli, across a distributed network of regions including left and right middle temporal gyrus, default mode network hubs, left and right posterior cerebellum/vermis, and putamen. Further analysis also revealed greater BOLD response in females compared to males, as well as in those with no prior experience of cyberbullying compared to those with prior experience (despite gender), when viewing the cyberbullying stimuli compared to the neutral stimuli. These results bring us closer to understanding the neurobiological underpinnings that may be associated with cybervictim/bully status and outcomes.

Investigating the links between adolescent sleep deprivation, fronto-limbic connectivity and the Onset of Mental Disorders: a review of the literature.

The importance of sleep for mental health has been known for some time. Although it was initially suggested that mental health conditions negatively impact sleep, it is now widely understood that this association is bidirectional. Adolescence is a period where people are at an increased risk of being sleep deprived largely due to a late shift in the circadian rhythm around puberty combined with early school start times. This combination may lead to adolescents being at an increased risk of mental health problems. Adolescence is also a period of continued brain development with white matter maturation continuing in the frontal brain regions throughout adolescence and into early adulthood. White matter development involves myelination of axons that link areas of grey matter and is integral for communication speed and efficiency. Studies have demonstrated that sufficient sleep is required for myelination to occur. The uncinate fasciculus (UF) is one of the last white matter tracts to be myelinated with this process occurring throughout adolescence and running between the amygdala in the limbic system and the orbitofrontal (OFC) and medial prefrontal cortices (mPFC). Recent studies have shown that connectivity between the amygdala and OFC is important for an individual's ability to exert top-down executive control over amygdala based automatic emotional responses to experiences perceived as threatening. The current literature review provides an overview of these mechanisms and concludes by proposing a model of adolescent sleep deprivation leading to potential life-long mental health issues through the moderating impact of reduced UF development.

Memory Performance Correlates of Hippocampal Subfield Volume in Mild Cognitive Impairment Subtype.

The increased understanding that neuropathology begins decades before symptom onset, has led to the conceptualization and widespread utilization of Mild Cognitive Impairment (MCI) as an important transitional state between healthy aging and dementia. Further subcategorization to MCI subtype has led to more distinct prognoses and it is widely considered that amnestic and non-amnestic MCI (aMCI, naMCI) likely have distinct pathophysiologies. Yet, accurately classification remains contentious. Here, we differentiate hippocampal subfield volume between subtypes, diagnosed according to stringent clinical consensus criteria, where aMCI is characterized based on deficits in delayed recall (rather than encoding). We then identify memory performance correlates to subfield volume and associations with long-term cognitive performance and outcome. 3D T1-weighted structural MRI was acquired in 142 participants recruited from the Healthy Brain Aging (HBA) Clinic and diagnosed with aMCI (n = 38), naMCI (n = 84) or subjective memory complaints (SMC; n = 20). T1-weighted datasets were processed with the cortical and hippocampal subfield processing streams in FreeSurfer (v6.0). Subfield volumes, and associations with baseline and longitudinal objective memory scores were then examined. Subfield volumes were found to differentiate clinical profiles: subiculum, CA1, CA4 and dentate gyrus volumes were significantly reduced in aMCI compared to both naMCI and SMC. CA1 subfield volume was shown to predict concurrent memory performance in aMCI, while dentate gyrus volume significantly predicted longitudinal verbal learning and memory decline in the entire cohort. Our findings demonstrate that using a more stringent diagnostic approach to characterizing aMCI is well justified, as delayed recall deficits are strongly linked to underlying volumetric subfield reductions in CA1, CA4 and the dentate gyrus, subfields known to be associated with mnemonic processes. Further research is now warranted to replicate these findings in other MCI samples.

Subcortical Volume Correlates of Psychological Distress in Early Adolescence.

The hippocampus and amygdala have justifiably been the focus of much mental health research due to their putative roles in top-down processing control of emotion, fear, and anxiety. However, understanding the causal relationship between these regions and mental illness has been limited as current literature is lacking in the observation of neuro-structural changes preceding first episodes. Here, we report whole and sub-structural hippocampal and amygdala volume correlates of psychological distress in early adolescence. Automated hippocampal subfield and amygdala nuclei segmentation was carried out in 32 participants (12-13 years old) recruited for the Longitudinal Adolescent Brain Study (LABS) who had psychological distress scores measured by the Kessler-10. Partial correlation analyses revealed significant negative association between left whole amygdala volume and psychological distress. Sub-structure analysis revealed that smaller left hippocampal CA1 volume and left basal and accessory basal amygdala nuclei volumes were all significantly associated with higher levels of psychological distress. Four-month follow-up analysis also revealed an association between change in K10 and CA1 volume suggesting a continued relationship between this hippocampal substructure and psychological distress. Grey matter volume of subcortical sub-structures involved within the hippocampal-basolateral amygdala-prefrontal cortex loop are highly correlated and are significantly reduced in adolescents with higher levels of psychological distress, indicating these nuclei and subfields play an important role in the emergence of mental illness.

Effect of cognitive-only and cognitive-motor training on preventing falls in community-dwelling older people: protocol for the smart±step randomised controlled trial.

BACKGROUND: Physical and cognitive impairments are important risk factors for falls in older people. However, no studies have been adequately powered to examine whether cognitive or cognitive-motor training can prevent falls in older people. This is despite good evidence of improvements in fall-related cognitive and physical functions following both intervention types. This manuscript describes the study protocol for a three-arm randomised controlled trial to evaluate the effectiveness of home-based cognitive and cognitive-motor training interventions, compared to a minimal-intervention control group, in preventing falls in older people. This trial was prospectively registered with the Australia New Zealand Clinical Trial Registry, number ACTRN12616001325493. METHODS AND ANALYSIS: Community-dwelling adults aged 65 years and over, residing in Sydney Australia, will be recruited. Participants (n=750) will be randomly allocated to (1) cognitive-only training, (2) cognitive-motor training or (3) control groups. Both training interventions involve the use of the smart±step home-based computerised game playing system for a recommended 120 min/week for 12 months. Cognitive training group participants will use a desktop electronic touch pad to play games with the smart±step system while seated and using both hands. The cognitive-motor training group participants will use a wireless electronic floor step mat that requires accurate stepping using both legs for playing the same smart±step games, hence incorporating balance exercises. All groups will receive an education booklet on fall prevention. The primary outcome will be rate of falls, reported by monthly diaries during the 12-month duration of the study and analysis will be by intention-to-treat. Secondary outcomes include the proportion of fallers, physical and cognitive performance in 300 participants, and brain structure and function in 105 participants who will undertake MRI scans at baseline and 6 months. Cost-effectiveness will be determined using intervention and health service costs. ETHICS AND DISSEMINATION: Ethical approval was obtained from UNSW Ethics Committee in September 2015 (ref number HC15203). Outcomes will be disseminated through publication in peer-reviewed journals and presentations at international conferences. TRIAL REGISTRATION NUMBER: ACTRN12616001325493.

Gender-specific structural abnormalities in major depressive disorder revealed by fixel-based analysis.

BACKGROUND: Major depressive disorder (MDD) is a chronic disease with a large global impact. There are currently no clinically useful predictors of treatment outcome, and the development of biomarkers to inform clinical treatment decisions is highly desirable. METHODS: In this exploratory study we performed fixel-based analysis of diffusion MRI data from the International Study to Predict Optimized Treatment in Depression with the aim of identifying novel biomarkers at baseline that may relate to diagnosis and outcome to treatment with antidepressant medications. Analyses used MR data from individuals with MDD (n = 221) and healthy controls (n = 67). RESULTS: We show focal, gender-specific differences in the anterior limb of the internal capsule (males) and bilaterally in the genu of the corpus callosum (females) associated with diagnosis. Lower fibre cross-section in the tapetum, the conduit between the right and left hippocampi, were also associated with a decreased probability of remission. Analysis of conventional fractional anisotropy showed scattered abnormalities in the corona radiata, cerebral peduncles and mid-brain which were much lower in total volume compared to fixel-based analysis. CONCLUSIONS: Fixel-based analysis appeared to identify different underlying abnormalities than conventional tensor-based metrics, with almost no overlap between significant regions. We show that MDD is associated with gender specific abnormalities in the genu of the corpus callosum (females) and in the anterior limb of the internal capsule (males), as well as gender-independent differences in the tapetum that predict remission. Diffusion MRI may play a key role in future guidance of clinical decision-making for MDD.

Alterations in white matter network topology contribute to freezing of gait in Parkinson's disease.

Freezing of gait (FOG) is a common symptom in advanced Parkinson's disease (PD). Despite current advances, the neural mechanisms underpinning this disturbance remain poorly understood. To this end, we investigated the structural organisation of the white matter connectome in PD freezers and PD non-freezers. We hypothesized that freezers would show an altered network architecture, which could hinder the effective information processing that characterizes the disorder. Twenty-six freezers and twenty-four well-matched non-freezers were included in this study. Using diffusion tensor imaging, we investigated the modularity and integration of the regional connectome by calculating the module degree z score and the participation coefficient, respectively. Compared to non-freezers, freezers demonstrated lower participation coefficients in the right caudate, thalamus, and hippocampus, as well as within superior frontal and parietal cortical regions. Importantly, several of these nodes were found within the brain's 'rich club'. Furthermore, group differences in module degree z scores within cortical frontal and sensory processing areas were found. Together, our results suggest that changes in the structural network topology contribute to the manifestation of FOG in PD, specifically due to a lack of structural integration between key information processing hubs of the brain.

4D flow magnetic resonance imaging: role in pediatric congenital heart disease.

Imaging-based evaluation of cardiac structure and function remains paramount in the diagnosis and monitoring of congenital heart disease in childhood. Accurate measurements of intra- and extracardiac hemodynamics are required to inform decision making, allowing planned timing of interventions prior to deterioration of cardiac function. Four-dimensional flow magnetic resonance imaging is a nonionizing noninvasive technology that allows accurate and reproducible delineation of blood flow at any anatomical location within the imaging volume of interest, and also permits derivation of physiological parameters such as kinetic energy and wall shear stress. Four-dimensional flow is the focus of a great deal of attention in adult medicine, however, the translation of this imaging technique into the pediatric population has been limited to date. A more broad-scaled application of 4-dimensional flow in pediatric congenital heart disease stands to increase our fundamental understanding of the cause and significance of abnormal blood flow patterns, may improve risk stratification, and inform the design and use of surgical and percutaneous correction techniques. This paper seeks to outline the application of 4-dimensional flow in the assessment and management of the pediatric population affected by congenital heart disease.

A modified echocardiographic approach improves reliability of superior vena caval flow quantification.

OBJECTIVE: To assess accuracy and repeatability of a modified echocardiographic approach to quantify superior vena cava (SVC) flow volume that uses a short-axis view to directly measure SVC area and a suprasternal view to measure flow velocity, both at the level of the right pulmonary artery. SETTING: Three tertiary-level neonatal intensive care units. DESIGN: This was a multicentre, prospective, observational study. Accuracy of the traditional and modified approach was first assessed by comparing echo measurements according to both techniques with Phase contrast MRI (PCMRI) assessments, in a cohort of 10 neonates. In a second cohort of 40 neonates, intraobserver scan-rescan repeatability and interobserver analysis-reanalysis repeatability were assessed by repeated SVC flow echo measurements, according to both techniques. RESULTS: The traditional echocardiographic approach to assessment of SVC flow had a moderate agreement with PCMRI (r2 0.259), a scan-rescan intraobserver repeatability index (RI) of 37% (limits of agreement (LOA) -47/+51 mL/kg/min) and an interobserver analysis-reanalysis RI of 31% (LOA -38/+40 mL/kg/min). The modified approach showed a stronger agreement with PCMRI (r2 0.775), an improved intraobserver scan-rescan repeatability (RI 22%, LOA -24/+18 mL/kg/min) and improved interobserver analysis-reanalysis repeatability (RI 18%, LOA -18/+20 mL/kg/min). CONCLUSIONS: Echocardiographic assessment of SVC flow volume by tracing area from a short-axis view and measuring velocity-time integral from a suprasternal view offered an improvement in accuracy and repeatability, building on the traditional approach previously described.

Impact of obesity and epicardial fat on early left atrial dysfunction assessed by cardiac MRI strain analysis.

BACKGROUND: Diastolic dysfunction is a major cause of morbidity in obese individuals. We aimed to assess the ability of magnetic resonance imaging (MRI) derived left atrial (LA) strain to detect early diastolic dysfunction in individuals with obesity and type 2 diabetes, and to explore the association between cardiac adipose tissue and LA function. METHODS: Twenty patients with obesity and T2D (55 ± 8 years) and nineteen healthy controls (48 ± 13 years) were imaged using cine steady state free precession and 2-point Dixon cardiovascular magnetic resonance. LA function was quantified using a feature tracking technique with definition of phasic longitudinal strain and strain rates, as well as radial motion fraction and radial velocities. RESULTS: Systolic left ventricular size and function were similar between the obesity and type 2 diabetes and control groups by MRI. All patients except four had normal diastolic assessment by echocardiography. In contrast, measures of LA function using magnetic resonance feature tracking were uniformly altered in the obesity and type 2 diabetes group only. Although there was no significant difference in intra-myocardial fat fraction, Dixon 3D epicardial fat volume(EFV) was significantly elevated in the obesity and type 2 diabetes versus control group (135 ± 31 vs. 90 ± 30 mL/m2, p < 0.001). There were significant correlations between LA functional indices and both BMI and EFV (p ≤ 0.007). CONCLUSIONS: LA MRI-strain may be a sensitive tool for the detection of early diastolic dysfunction in individuals with obesity and type 2 diabetes and correlated with BMI and epicardial fat supporting a possible association between adiposity and LA strain. Trials Registration Australian New Zealand Clinical Trials Registry No. ACTRN12613001069741.