Dora C.-H. Kuan

An inflammatory pathway links atherosclerotic cardiovascular disease risk to neural activity evoked by the cognitive regulation of emotion.

BACKGROUND Cognitive reappraisal is a form of emotion regulation that alters emotional responding by changing the meaning of emotional stimuli. Reappraisal engages regions of the prefrontal cortex that support multiple functions, including visceral control functions implicated in regulating the immune system. Immune activity plays a role in the preclinical pathophysiology of atherosclerotic cardiovascular disease (CVD), an inflammatory condition that is highly comorbid with affective disorders characterized by problems with emotion regulation. Here, we tested whether prefrontal engagement by reappraisal would be associated with atherosclerotic CVD risk and whether this association would be mediated by inflammatory activity. METHODS Community volunteers (n = 157; 30-54 years of age; 80 women) without DSM-IV Axis-1 psychiatric diagnoses or cardiovascular or immune disorders performed a functional neuroimaging task involving the reappraisal of negative emotional stimuli. Carotid artery intima-media thickness and inter-adventitial diameter were measured by ultrasonography and used as markers of preclinical atherosclerosis. Also measured were circulating levels of interleukin-6 (IL-6), an inflammatory cytokine linked to CVD risk and prefrontal neural activity. RESULTS Greater reappraisal-related engagement of the dorsal anterior cingulate cortex was associated with greater preclinical atherosclerosis and IL-6. Moreover, IL-6 mediated the association of dorsal anterior cingulate cortex engagement with preclinical atherosclerosis. These results were independent of age, sex, race, smoking status, and other known CVD risk factors. CONCLUSIONS The cognitive regulation of emotion might relate to CVD risk through a pathway involving the functional interplay between the anterior cingulate region of the prefrontal cortex and inflammatory activity.

Resting state connectivity of the medial prefrontal cortex covaries with individual differences in high‐frequency heart rate variability

Resting high-frequency heart rate variability (HF-HRV) relates to cardiac vagal control and predicts individual differences in health and longevity, but its functional neural correlates are not well defined. The medial prefrontal cortex (mPFC) encompasses visceral control regions that are components of intrinsic networks of the brain, particularly the default mode network (DMN) and the salience network (SN). Might individual differences in resting HF-HRV covary with resting state neural activity in the DMN and SN, particularly within the mPFC? This question was addressed using fMRI data from an eyes-open, 5-min rest period during which echoplanar brain imaging yielded BOLD time series. Independent component analysis yielded functional connectivity estimates defining the DMN and SN. HF-HRV was measured in a rest period outside of the scanner. Midlife (52% female) adults were assessed in two studies (Study 1, N = 107; Study 2, N = 112). Neither overall DMN nor SN connectivity strength was related to HF-HRV. However, HF-HRV related to connectivity of one region within mPFC shared by the DMN and SN, namely, the perigenual anterior cingulate cortex, an area with connectivity to other regions involved in autonomic control. In sum, HF-HRV does not seem directly related to global resting state activity of intrinsic brain networks, but rather to more localized connectivity. A mPFC region was of particular interest as connectivity related to HF-HRV was shared by the DMN and SN. These findings may indicate a functional basis for the coordination of autonomic cardiac control with engagement and disengagement from the environment.

Fish oil supplementation does not lower C-reactive protein or interleukin-6 levels in healthy adults.

The n‐3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may prevent a range of chronic conditions through anti‐inflammatory actions. However, as clinical trials using these fatty acids for primary prevention are yet unavailable, their putative role in disease prevention rests, in part, on evidence of anti‐inflammatory actions in healthy individuals.

Systemic Inflammation and Resting State Connectivity of the Default Mode Network.

The default mode network (DMN) encompasses brain systems that exhibit coherent neural activity at rest. DMN brain systems have been implicated in diverse social, cognitive, and affective processes, as well as risk for forms of dementia and psychiatric disorders that associate with systemic inflammation. Areas of the anterior cingulate cortex (ACC) and surrounding medial prefrontal cortex (mPFC) within the DMN have been implicated specifically in regulating autonomic and neuroendocrine processes that relate to systemic inflammation via bidirectional signaling mechanisms. However, it is still unclear whether indicators of inflammation relate directly to coherent resting state activity of the ACC, mPFC, or other areas within the DMN. Accordingly, we tested whether plasma interleukin (IL)-6, an indicator of systemic inflammation, covaried with resting-state functional connectivity of the DMN among 98 adults aged 30-54 (39% male; 81% Caucasian). Independent component analyses were applied to resting state fMRI data to generate DMN connectivity maps. Voxel-wise regression analyses were then used to test for associations between IL-6 and DMN connectivity across individuals, controlling for age, sex, body mass index, and fMRI signal motion. Within the DMN, IL-6 covaried positively with connectivity of the sub-genual ACC and negatively with a region of the dorsal medial PFC at corrected statistical thresholds. These novel findings offer evidence for a unique association between a marker of systemic inflammation (IL-6) and ACC and mPFC functional connectivity within the DMN, a network that may be important for linking aspects of immune function to psychological and behavioral states in health and disease.

Community Socioeconomic Disadvantage in Midlife Relates to Cortical Morphology via Neuroendocrine and Cardiometabolic Pathways

Abstract Residing in communities of socioeconomic disadvantage confers risk for chronic diseases and cognitive aging, as well as risk for biological factors that negatively affect brain morphology. The present study tested whether community disadvantage negatively associates with brain morphology via 2 biological factors encompassing cardiometabolic disease risk and neuroendocrine function. Participants were 448 midlife adults aged 30‐54 years (236 women) who underwent structural neuroimaging to assess cortical and subcortical brain tissue morphology. Community disadvantage was indexed by US Census data geocoded to participants’ residential addresses. Cardiometabolic risk was indexed by measurements of adiposity, blood pressure, glucose, insulin, and lipids. Neuroendocrine function was indexed from salivary cortisol measurements taken over 3 days, from which we computed the cortisol awakening response, area‐under‐the‐curve, and diurnal cortisol decline. Community disadvantage was associated with reduced cortical tissue volume, cortical surface area, and cortical thickness, but not subcortical morphology. Moreover, increased cardiometabolic risk and a flatter (dysregulated) diurnal cortisol decline mediated the associations of community disadvantage and cortical gray matter volume. These effects were independent of age, sex, and individual‐level socioeconomic position. The adverse risks of residing in a disadvantaged community may extend to the cerebral cortex via cardiometabolic and neuroendocrine pathways.

Associations of immunometabolic risk factors with symptoms of depression and anxiety: The role of cardiac vagal activity

OBJECTIVES This study examined 1) the cross-sectional relationships between symptoms of depression/anxiety and immunometabolic risk factors, and 2) whether these relationships might be explained in part by cardiac vagal activity. METHODS Data were drawn from the Adult Health and Behavior registries (n = 1785), comprised of community dwelling adults (52.8% women, aged 30-54). Depressive symptoms were measured with the Center for Epidemiological Studies Depression Scale (CES-D) and the Beck Depression Inventory-II (BDI-II), and anxious symptoms with the Trait Anxiety scale of the State-Trait Anxiety Inventory (STAI-T). Immunometabolic risk factors included fasting levels of triglycerides, high-density lipoproteins, glucose, and insulin, as well as blood pressure, waist circumference, body mass index, C-reactive protein, and interleukin-6. Measures of cardiac autonomic activity were high- and low-frequency indicators of heart rate variability (HRV), standard deviation of normal-to-normal R-R intervals, and the mean of absolute and successive differences in R-R intervals. RESULTS Higher BDI-II scores, in contrast to CES-D and STAI-T scores, were associated with increased immunometabolic risk and decreased HRV, especially HRV likely reflecting cardiac vagal activity. Decreased HRV was also associated with increased immunometabolic risk. Structural equation models indicated that BDI-II scores may relate to immunometabolic risk via cardiac vagal activity (indirect effect: β = .012, p = .046) or to vagal activity via immunometabolic risk (indirect effect: β = -.015, p = .021). CONCLUSIONS Depressive symptoms, as measured by the BDI-II, but not anxious symptoms, were related to elevated levels of immunometabolic risk factors and low cardiac vagal activity. The latter may exhibit bidirectional influences on one another in a meditational framework. Future longitudinal, intervention, an nonhuman animal work is needed to elucidate the precise and mechanistic pathways linking depressive symptoms to immune, metabolic, and autonomic parameters of physiology that predispose to cardiovascular disease risk.