Psychological and neurobiological mechanisms involved in the relationship between loneliness and cognitive decline in older adults.

Loneliness, among older adults, is one of the risk factors for developing dementia. Still, little is known about the neurobiological and psychological conditions that link loneliness to cognitive decline. The current study investigated several research aims: First, it sought to identify neurobiological and psychological pathways that may account for the relationship between loneliness and decline across several cognitive domains. These pathways included depressive symptoms, total gray matter volume, and conditional analyses of pro-inflammatory cytokines and brain-derived neurotrophic factor (BDNF) expression. Second, it examined loneliness as a predictor of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Third, it sought to determine whether the relationship between loneliness and cognitive decline is sex-specific in older adults. Longitudinal data were collected from 2130 Rush Memory and Aging Project participants. Participants underwent annual cognitive and psychological assessments and neuroimaging procedures every year. BDNF gene expression was measured in the dorsolateral prefrontal cortex, cytokines were measured in serum, and the final consensus clinical diagnosis was identified at the time of death. All linear mixed and multinomial logistic regression models controlled for age at baseline, education, sex, and APOE genotype. Participants were largely women (73 %), and Caucasian (93 %). The average education was 14.93 (SD = 3.34). The average age at baseline was 80.05 (SD = 7.57). Results showed that gray matter volume and depressive symptoms partially mediated the relationship between loneliness and cognitive decline. There was a significant interaction between loneliness and BDNF expression in relation to cognitive decline. Higher levels of BDNF expression was associated with slower decline in semantic memory and visuospatial ability. Finally, the current study also established that higher levels of loneliness was positively associated with the incidence of AD and other dementias. The present findings support the growing literature, which tends to show that the consequence of loneliness goes beyond the feeling of being isolated. Loneliness may induce physiological changes in our brains, leading to cognitive decline. Future research can explore a wide range of biological and psychological expressions of loneliness to clarify how loneliness relates to dementia.

The Mediating Role of Inflammation in the Relationship Between α-Synuclein and Cognitive Functioning.

Accumulating evidence suggests that α-synuclein plays a role in the pathophysiology of Alzheimer's disease (AD). This study examined whether α-synuclein level in cerebrospinal fluid (CSF) was associated with cognitive functioning among older adults. We also explored whether this relationship was mediated by proinflammatory cytokines TNF-α and IL-6, along with sIL-6R and vascular endothelial growth factor (VEGF). Using a cross-sectional Alzheimer's Disease Neuroimaging Initiative (ADNI; N = 148) sample, we examined the relationship between α-synuclein and participants' performance on Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-Cog 13) at baseline. Mediation analyses were utilized, adjusting for age, education, APOEe4, and Geriatric Depression Scale scores. All biological markers were measured in CSF. Participants in the current sample were 58.3% males, 41.7% females, and Caucasian (95.5%); their average education and age were 15.5 (standard deviation [SD] = 2.97) and 74.4 (SD = 7.51) years, respectively. Higher accumulation of α-synuclein was associated with poorer MMSE scores (ß = -0.41, standard error [SE] = 1.54, p < .001). This relationship appeared to be mediated by VEGF (ß = 0.27, SE = 2.15, p = .025) and IL-6r (ß = 0.22, SE = 1.66, p < .026). In addition, α-synuclein was associated with poorer performance on the ADAS-Cog 13 (ß = 0.34, p = .005) and mediated by VEGF (ß = -0.19, SE = 4.13, p = .025) after adjusting for age, education, APOEe4, and depressive symptoms. α-Synuclein may serve as an additional biomarker for determining poor cognitive functioning. VEGF and IL-6 soluble receptors were significant mediators of the relationship between α-synuclein and cognitive functioning. If confirmed in prospective analyses, these findings can further inform the pathologic cascade and early diagnosis of AD.

The Role of Race in Relations of Social Support to Hippocampal Volumes Among Older Adults.

Evidence suggests social support may buffer brain pathology. However, neither its association with hippocampal volume, a marker of Alzheimer's disease risk, nor the role of race in this association has been fully investigated. Multiple regression analyses examined relations of total social support to magnetic resonance imaging-assessed gray matter (GM) hippocampal volumes in the total sample (n = 165; mean age = 68.48 year), and in race-stratified models of African American and White older adults, adjusting for select covariates. Results showed greater social support was associated with greater GM hippocampal volumes among African American older adults only (p < .01). Our findings suggest greater total social support may play a role in supporting the hippocampus, particularly among African American older adults, who had lower hippocampal volumes than their White counterparts. Further research is needed to test these questions longitudinally and examine which aspects of social support may promote hippocampal integrity, specifically.

The impact of social constraints on insomnia among African-American breast cancer survivors: The mediating role of fear of recurrence.

OBJECTIVE: Insomnia is a significant concern among African-American breast cancer survivors (BCS). Social constraints (SC)-receiving unsupportive or critical responses when expressing trauma-related emotions-and fear of recurrence (FOR) have been associated with insomnia. We examined FOR as a mediator in the relationship between SC and insomnia in African-American BCS. We hypothesized a direct effect of SC on insomnia, and an indirect effect of SC on insomnia through FOR. METHODS: Sixty-four African-American BCS completed a questionnaire assessing demographics, clinical characteristics, SC, FOR, and insomnia. Participants were an average of M = 8.41 (SD = 5.8) year survivors. The mediation was tested using PROCESS for SPSS. RESULTS: The direct effect of SC on insomnia was significant (direct effect = .17, SE = .08, P = .04). Moreover, the indirect effect of SC on insomnia through FOR was significant (indirect effect = .19, SE = .10, 95% CI = .05, .41). CONCLUSIONS: Experiencing SC from family and friends could produce cognitions that impact sleep for BCS, and FOR could be one of those cognitions. Family-based models of care that emphasize the emotional needs of survivors and families could be a relevant strategy to address the SC that impacts sleep.

Influence of Spirituality on Depression-Induced Inflammation and Executive Functioning in a Community Sample of African Americans.

African Americans (AAs) are disproportionately affected by cerebrovascular pathology and more likely to suffer from premature cognitive decline. Depression is a risk factor for poorer cognitive functioning, and research is needed to identify factors that serve to mitigate its negative effects. Studies have demonstrated positive influences of spirituality within the AA community. Determining whether spirituality attenuates the effects of depressive symptoms on cognitive functioning and the pathophysiological mechanisms that explain these relationships in AAs is paramount. This study examines the influence of daily spiritual experiences on the relationship between depressive symptoms and cognitive functioning, and how inflammatory markers may partially explain these associations. A sample of 212 (mean age= 45.6) participants completed the Daily Spiritual Experience Scale (DSES), Beck Depression Inventory-II (BDI-II), Trail Making Test A and B (TMT) and Stroop Color and Word Test (Stroop). Blood samples were collected to measure inflammatory mediators (IL-6, IL-1a, TNF-a). Linear regression analyses were used to evaluate associations. Higher BDI-II scores were associated with poorer psychomotor speed and visual scanning, measured by TMT A (B=1.49, P=.01). IL-6 explained a significant amount of variance in this relationship (B=.24, CI 95% [.00, .64]). IL-6 also significantly mediated the relationship between depressive symptoms and psychomotor speed and mental flexibility, measured by TMT B performance (B=.03, CI 95% [.003, .095]). Frequent spiritual experiences among AAs may ameliorate the negative influence of depressive symptoms on cognitive functioning.

Examining the Influence of Measures of Adiposity on Cognitive Function in Middle Age and Older African Americans.

The objectives of the study were to examine whether measures of total obesity (body mass index [BMI]) and central obesity (waist circumference [WC] and waist-to-hip ratio [WHR]) are associated with cognitive function in African Americans, and whether sex moderates these associations. A sample of 194 African Americans, with a mean age of 58.97 years, completed a battery of cognitive tests and a self-reported health questionnaire. Height, weight, waist and hip circumference, and blood pressure were assessed. Linear regression analyses were run. Results suggested lower performance on measures of verbal fluency and complex attention/cognitive flexibility was accounted for by higher levels of central adiposity. Among men, higher WHR was more strongly related to complex attention/cognitive flexibility performance, but for women, WC was a salient predictor. Higher BMI was associated with poorer verbal memory performance among men, but poorer nonverbal memory performance among women. Findings suggest a need for healthy lifestyle interventions for African Americans to maintain healthy weight and cognitive function.

Age at Immigration and Kidney Function among Self-Identified Healthy Africans in the United States.

Kidney disease disparately affects those of African descent. Age trends have generally been established for kidney function in the overall US population, but the contribution of age at the time of immigration for African immigrants is unknown. To examine the independent and joint effects of age and age at the time of immigration, and kidney function. Estimated glomerular filtration rate (eGFR) was calculated for 93 African immigrants (60 % male; mean age = 33.5). Hierarchical regression and post hoc analyses revealed a significant age × age at the time of immigration interaction after accounting for traditional risk factors among those who immigrated at age ≤21. Younger age at the time of immigration to the US may exacerbate an inverse relationship between age and kidney function in a self-identified healthy African immigrant sample. Investigation of biopsychosocial factors associated with kidney health among African immigrants is warranted.

Understanding African American college students' H1N1 vaccination decisions.

OBJECTIVE: In this study, we examined the effects of cognitive appraisals and individual differences in discomfort with uncertainty, as measured by a short form of Webster and Kruglanski's (1994) Need for Closure (NFC) scale, on African American college students' self-reported H1N1 vaccination decisions during the 2009-2010 H1N1 pandemic. METHOD: Howard University undergraduates, who self-identified as Black or African American and met U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC) H1N1 high-priority group criteria, completed computer-administered surveys that included (a) questions about H1N1 vaccination status; self-efficacy; perceived costs, benefits, and efficaciousness of the H1N1 vaccine; and potential barriers to vaccination, including flu-shot frequency; (b) demographic measures; and (c) a short form of Kruglanski's NFC scale (Orehek et al., 2010). RESULTS: A sequential multinomial logistic regression revealed (a) a significant effect of NFC on vaccination status such that higher NFC was associated with lower odds of being vaccinated or intending to be vaccinated, after controlling for demographic variables, comfort with flu vaccinations more generally, and several other potential vaccination barriers, χ(2)(2, 217) = 10.08, p = .006; and (b) vaccination status was best accounted for by a model that included perceptions of the vaccine's costs, benefits, and efficaciousness, and participants' self-efficacy for being vaccinated, χ(2)(6, 217) = 57.24, p < .001. CONCLUSION: Our data suggest the importance of cognitive appraisals and traits (i.e., comfort with uncertainty) in the process individuals use to make potentially life-saving vaccination decisions.

The Combined Influence of Psychological Factors on Biomarkers of Renal Functioning in African Americans.

OBJECTIVE: African Americans are disproportionately affected by chronic kidney disease (CKD). Recent research has documented that psychological-factors have a significant influence on the progression and treatment of CKD. However, extant evidence exists that has examined the link between psychological factors and renal function in African Americans. The purpose of the study was to determine if psychological factors were associated with several biomarkers of renal functioning in this group. PARTICIPANTS: 129 African American participants, with a mean age of 44.4 years (SD = 12.25). DESIGN AND SETTING: Data were analyzed from a cross-sectional study entitled Stress and Psychoneuroimmunological Factors in Renal Health and Disease. MAIN PREDICTOR MEASURES: Participants completed the Beck Depression Inventory-II, Cook Medley Scale, and Perceived Stress Scale-10. MAIN OUTCOME MEASURES: Systolic blood pressure, as well as blood and urine samples, were collected and served as biomarkers of renal functioning. RESULTS: Our findings indicated that psychological factors were not associated with renal functioning. Age, sex, and systolic blood pressure emerged as significant predictors of renal functioning. CONCLUSIONS: Depressive symptomatology, perceived stress, and hostility did not influence renal functioning in this sample. This unexpected finding may be attributed to the fact that this sample population was not elevated on depressive symptoms, perceived stress, or hostility. Elevated levels of these psychological factors, as well as other psychological factors associated with the CKD, may be more influential on renal functioning in African Americans.

Depressive symptomatology and respiratory sinus arrhythmia in a non-clinical sample of middle-aged African Americans.

Decreased heart rate variability and depression are both independent risk factors for cardiac mortality in clinical and non-clinical samples. The purpose of the current study is to examine the hypothesis that severity of depressive symptomatology is inversely associated with respiratory sinus arrhythmia (RSA) in a non-clinical sample of African Americans. The sample included 77 African Americans with a mean age of 48.4 (SD = 11.7). Participants completed the Beck Depression Inventory-II (BDI-II) and a 5-min resting baseline measurement of RSA was collected. The BDI-II total score was positively associated with RSA (ß = .334, p = .008). Given the unexpected direction of the association, we separated the BDI-II into cognitive and somatic affective subscales to identify which construct was driving the relationship. The somatic affective, was related to RSA (ß = .328, p = .010), but not the cognitive subscale. Given this unexpected positive result, future research should further examine the nature of the relationship between depressive symptomatology and RSA in African Americans, as the relationship may vary based on levels of depressive symptomatology.

Executive function and negative eating behaviors in severely obese African Americans.

OBJECTIVE: African Americans are disparately impacted by severe obesity. Low socioeconomic status and psychosocial risk factors help to explain this disparity; however, few studies have examined the role of negative eating behaviors or the influence of executive function on negative eating behaviors in this population. The objective was to examine the association between executive function (ie, inhibition and set shifting) and negative eating behaviors in severely obese African Americans. PARTICIPANTS: Forty-seven African Americans who met criteria for severe obesity participated. DESIGN AND SETTING: Data were analyzed from a cross-sectional study entitled Stress and Psychoneuroimmunological Factors in Renal Health and Disease. The mean age of participants was 45.7 years (SD = 10.8) and the mean educational attainment was 13 years (SD = 2.1). MAIN OUTCOME MEASURES: Participants completed the Wisconsin Card Sorting Task, the Stroop Color-Word Test, and the Eating Behavior Patterns Questionnaire. RESULTS: Correlation results suggested poorer inhibition was associated with greater self-reported emotional eating and snacking on sweets. Subsequent hierarchical regression analyses confirmed the inverse relations between inhibition, emotional eating, and snacking on sweets, after controlling for age, sex, years of education, and depression. CONCLUSIONS: Reduced inhibition may be an important risk factor for negative eating behaviors and subsequent obesity in this population. Interventions aimed at increasing inhibition and self-regulation in this at-risk group are warranted.

Dispositional depression and hostility are associated with inflammatory markers of cardiovascular disease in African Americans.

Prior research has demonstrated that state depressive symptoms and hostility can modulate inflammatory immune responses and directly contribute to cardiovascular disease (CVD) onset and development. Previous studies have not considered the contribution of dispositional depressive symptoms to the inflammatory process. They have also largely excluded African Americans, despite their disproportionate risk for CVD. The first aim of the study was to examine the impact of state and dispositional depression and hostility on CVD-associated inflammatory biomarkers interleukin-6 (IL-6) and C-reactive protein (CRP) in an African American sample. The second aim was to examine synergistic influences of hostility and state and dispositional depression on IL-6 and CRP. The final aim was to examine whether the relations between state and dispositional depression, hostility, IL-6, and CRP varied as a function of gender and education. Anthropometric measures, blood serum samples, and psychosocial data were collected from 198 African Americans from the Washington, DC metropolitan area. Hierarchical and stepwise regression analyses indicated that (1) increased levels of hostility were associated with increased levels of CRP; (2) hostility and IL-6 were more strongly associated among participants with lower educational attainment; and (3) dispositional depression and CRP were more strongly associated among participants with greater hostility and lower educational attainment. Findings suggest that enduring personality dispositions, such as dispositional depression and hostility, are critical to a thorough assessment of cardiovascular profiles in African Americans. Future studies should investigate causal pathways that link depressive and hostile personality styles to inflammatory activity for African American men and women.

Psychometric properties of the Cook Medley hostility scale and its association with inflammatory markers in African Americans.

Dispositional hostility as measured by the Cook Medley Hostility (Ho) Scale has been associated with inflammation and cardiovascular disease (CVD) risk. There is evidence that suggests that factors of hostility are more useful in predicting poor cardiovascular health outcomes than a single hostility construct. The purpose of this study was to investigate the latent factors of hostility and their association with inflammatory markers interleukin-6 (IL-6) and C-reactive protein (CRP) in an African-American community sample. This racial/ethnic group has been largely excluded from this line of research despite their disproportionate burden of CVD and its risk factors. Blood samples for plasma IL-6 and CRP were collected on the same day the Ho Scale was administered. Plasma IL-6 and CRP levels were determined using enzymatic-linked immunosorbent assay. Confirmatory factor analysis revealed three latent main factors of hostility: Neuroticism, Manichaeism and Moral Primitiveness, and seven intermediary subfactors. Of the subfactors, hostile affect was significantly associated with greater CRP levels and predatory self interest was significantly associated with greater IL-6 levels. Findings suggest that African Americans have a unique pattern of hostility and two latent subfactors are associated with a marker of CVD. Based on the findings, future studies should aim to further delineate how hostility influences health outcomes in African Americans.

The influence of coping with perceived racism and stress on lipid levels in African Americans.

BACKGROUND: Lipid dysregulation is a major contributor to cardiovascular disease (CVD) risk and is attributed to numerous biological, psychosocial, and behavioral risk factors. Psychological stress has been examined as a predictor of lipid dysregulation; however, the role of coping with perceived racism, a stressor unique to the African American experience, has not been addressed. The current study sought to determine the impact of behavioral coping responses to perceived racism and perceived daily stress on lipid levels in African Americans. METHODS: The sample consisted of 122 African American participants who resided in the Washington, DC, metropolitan area. Data were collected as part of an ongoing study entitled Stress and Psychoneuroimmunological Factors in Renal Health and Disease at Howard University Hospital. RESULTS: Through canonical analysis, distinct profiles of African American lipid function emerged with body mass index, age, and behavioral coping responses to perceived racism being associated with high-density lipoprotein cholesterol (HDL-C), triglycerides, and low-density lipoprotein cholesterol (LDL-C), respectively. Results from linear regression analyses showed that greater endorsement of behavioral coping responses to perceived racism items predicted higher levels of LDL (B = .24, p < .05). This relationship was not mediated by pathophysiological mechanisms associated with the stress response system such as cortisol, norepinephrine, epinephrine, and IL-6. CONCLUSION: The relationship between elevated levels of LDL and behavioral coping responses to perceived racism suggests that African Americans may be at increased risk for CVD due to the unique stress encountered by racism in our culture. Behavioral pathways used to counteract the negative effects of perceived discrimination may better explain this relationship. Further research is necessary to determine other biobehavioral and pathophysiological mechanisms that explain this relationship.

Coping with perceived racism: a significant factor in the development of obesity in African American women?

BACKGROUND: African American women have the highest rates of obesity in the United States. The prevalence of obesity in this group calls for the identification of psychosocial factors that increase risk. Psychological stress has been associated with obesity in women; however, there is scant literature that has explored the impact of racism on body mass index (BMI) in African American women. OBJECTIVE: The current study aimed to determine whether emotional responses and behavioral coping responses to perceived racism were associated with BMI in African American women. METHODS: A sample of 110 African American women participated in a community-based study. Height and weight measurements were taken to calculate BMI and participants completed the Perceived Racism Scale and the Perceived Stress Scale. RESULTS: Hierarchical regression analyses demonstrated a significant relationship between BMI and behavioral coping responses to perceived racism. Findings for emotional responses to perceived racism and appraisal of one's daily life as stressful were nonsignificant. Mean comparisons of BMI groups showed that obese African American women used more behavioral coping responses to perceived racism as compared to normal-weight and overweight women in the sample. CONCLUSION: Findings suggest that behavioral coping responses better explained increased risk for obesity in African American women. A biobehavioral pathway may explain this finding with a stress-response process that includes cortisol reactivity. Maladaptive behavioral coping responses may also provide insight into obesity risk. Future research is needed to determine which behavioral coping responses place African American women at greater risk for obesity.

The influence of functional social support on executive functioning in middle-aged African Americans.

Social support has a positive influence on cognitive functioning and buffers cognitive decline in older adults. This study examined the relations between social support and executive functioning in middle-aged adults. A community-based sample of African Americans completed the Interpersonal Support Evaluation List, a measure of functions of social support, and two measures of executive functioning, the Stroop Color and Word Test and the Wisconsin Card Sorting Test (WCST). Hierarchical regression analyses were used to explore the hypothesis that different facets of perceived social support influence performance on measures of executive functioning. After controlling for age, gender, and education, social support facets including belonging support, self-esteem support, appraisal support, and tangible support were significant predictors of Stroop performance. In addition, tangible support significantly predicted WCST performance. These findings add to previous literature on social support and cognition; however, findings for middle-aged adults are unique and suggest that social support has a positive influence on some executive functions in African Americans prior to old age.