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.

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.

Factors Associated with Exercise Motivation among African-American Men.

OBJECTIVE: The primary aims of this study were to: (1) characterize exercise stages of change among a sample of African-American men, (2) determine if exercise motivation was associated with self-reported exercise behavior, and (3) examine if groups of personal (i.e., age, BMI, income, educational attainment, and perceived health), psycho-social (i.e., exercise self-efficacy, personality type, social influence), and environmental factors (i.e., neighborhood safety) predicted stages of change for physical exercise among African-American men. METHODS: One hundred seventy African-American male participants were recruited for this study (age: 47.63(10.23) years). Participants completed a self-report questionnaire assessing study variables. Multinomial logistic regression models were used to examine the association of exercise stages of change with an array of personal, psychosocial, and environmental factors. RESULTS: BMI, exercise self-efficacy, and nighttime neighborhood safety were entered as independent variables in the full model. BMI and exercise self-efficacy continued to be significant predictors of exercise stages of change in the full model. Obese men had a 9.24 greater odds of being in the action stage of change than in the maintenance stage. Also, men reporting greater exercise self-efficacy had lower odds of being in the lower stages of change categories (pre-preparation, preparation, and action) than in the maintenance stage. CONCLUSION: Our results confirmed that using an ecological framework explained more of the variance in exercise stages of change than any of the individual components alone. Information gleaned from this study could inform interventionists of the best ways to create tailored exercise programs for African-American men.

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.

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.

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.

Exaggerated vasopressor response to exercise and cerebral blood flow velocity.

We studied 10 young adults, normotensive at rest, comprising a control group (n = 5) with normal blood pressure responsiveness to exercise and an experimental group exhibiting greater percentage of body fat and body mass index (BMI) than the controls, with exaggerated blood pressure (vasopressor) responsiveness to exercise (EEBPR) (n = 5). Lower absolute and varying oxygen consumption/body weight normalized units of middle cerebral arterial blood flow velocity (MCAV) were found during exercise in the experimental group (P < .01). These findings support the hypothesis that the combination of EEBPR and high BMI is associated with low MCAV that may put such individuals at risk for cerebral hypoperfusion and cognitive deficits.

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.

Relationships among blood pressure, triglycerides and verbal learning in African Americans.

BACKGROUND: Individuals at greater risk for cardiovascular disease (CVD) display poorer cognitive functioning across various cognitive domains. This finding is particularly prevalent among older adults; however, few studies examine these relationships among younger adults or among African Americans. PURPOSE: The objective was to examine the relationships among 2 cardiovascular risk factors, elevated blood pressure and elevated triglycerides, and verbal learning in a community-based sample of African Americans. METHODS: Measurements of blood pressure and triglycerides were obtained in 121 African-American adults and compared to performance on 3 domains of the California Verbal Learning Test-II (CVLT-II). RESULTS: Blood pressure was not related to CVLT-II performance. Triglyceride levels were inversely related to CVLT-II performance. Higher triglyceride levels were associated with poorer immediate, short delay and long delay recall. CONCLUSIONS: Consistent with studies involving older participants, the current investigation shows that in a nonelderly sample of African Americans, triglyceride levels may be related to cognitive functioning. Because early detection and intervention of vascular-related cognitive impairment may have a salutary effect, future studies should include younger adults to highlight the impact of cardiovascular risk on cognition.

Perceived stress and eating behaviors in a community-based sample of African Americans.

Previous studies have reported that psychological stress is associated with greater food consumption, particularly consumption of high fat foods. We are unaware of any studies that have examined stress-induced eating among African Americans (AAs). The goals of the current study were to examine the relationship between perceived stress and high fat eating behaviors in a sample of AAs, to examine whether this relationship is stronger among overweight and obese participants, and to examine whether haphazard meal planning mediates the relationship between perceived stress and high fat eating behaviors. One hundred fifty-nine adults from a metropolitan area completed the Perceived Stress Scale (PSS-10), the Eating Behaviors Pattern Questionnaire (EBPQ), a demographic questionnaire, and body mass was assessed with BMI. Perceived stress was associated with haphazard planning and emotional eating, but not related to other high fat eating domains in the overall sample. These findings held for overweight and obese participants with the addition of snacking on sweets. High fat eating behaviors were not mediated by haphazard meal planning. These findings are consistent with other studies which demonstrate a link between stress and eating. Long-term interventions for high fat consumption and obesity should include an examination of perceived stress among AAs.

Patterns of relationships between cardiovascular disease risk factors and neurocognitive function in African Americans.

OBJECTIVE: The association between cardiovascular disease (CVD) risk and neurocognitive function has gathered a good deal of attention in the health and social science literature; however, the relationship among several CVD risk factors and neurocognitive function has not been fully explored in an African American sample. The purpose of this study was to examine the pattern of relationships among four CVD risk factors and five measures of higher cortical functions. METHODS: Data were collected from a sample of 106 African American community-dwelling adults in the metropolitan Washington, DC, area. A nurse collected blood pressure, waist circumference, and a blood sample (to assess triglycerides and high-density lipoprotein (HDL) cholesterol) from study participants. Participants completed the Symbol Digit Modalities Test, Trailmaking B, Stroop Color-word Task, California Verbal Learning Test-II, and Wisconsin Card Sorting Test as assessments of neurocognitive function. Canonical analysis and multiple regression analysis were the major statistical methods utilized to assess relationships between CVD risk factors and neurocognitive function. RESULTS: The results suggest that 1) attentional processes are associated with diastolic blood pressure levels, 2) verbal learning processes are associated with diastolic blood pressure and triglyceride levels, and 3) the ability to shift cognitive set is associated with HDL cholesterol levels. CONCLUSION: As cardiovascular health worsens in our society, particularly among ethnic minorities, the neurocognitive consequences must be clearly understood. Future studies should focus on identifying and building awareness of cardiovascular and neurocognitive links through longitudinal research designs and brain imaging technology.

Caveats in the neuropsychological assessment of African Americans.

This preliminary investigation examined the predictive accuracy of six neuropsychological tests in a population of non-brain-injured African Americans. False positives were unacceptably high on five of the neuropsychological tests administered. These pilot data raise important questions about the utility of neuropsychological test norms with groups dissimilar in sociocultural background to the normative population. These findings are examined in terms of the relative merits of the race-homogenous and race-comparative paradigms and underscore the importance of conducting normative studies that involve ethnic minority populations.