Predictors of serum testosterone and DHEAS in African-American men

Low circulating adropin levels in late-middle aged African Americans with poor cognitive performance

We recently reported accelerated cognitive decline in Europeans aged > 70 years with low circulating adropin levels. Adropin is a small, secreted peptide that is highly expressed in the human nervous system. Expression profiling indicate relationships between adropin expression in the human brain and pathways that affect dementia risk. Moreover, increased adropin expression or treatment using synthetic adropin improves cognition in mouse models of aging. Here we report that low circulating adropin concentrations associate with poor cognition (worst quintile for a composite score derived from the MMSE and semantic fluency test) in late-middle aged community-dwelling African Americans (OR = 0.775, P < 0.05; age range 45-65 y, n = 352). The binomial logistic regression controlled for sex, age, education, cardiometabolic disease risk indicators, and obesity. Previous studies using cultured cells from the brains of human donors suggest high expression in astrocytes. In snRNA-seq data from the middle temporal gyrus (MTG) of human donors, adropin expression is higher in astrocytes relative to other cell types. Adropin expression in all cell-types declines with advance age, but is not affected by dementia status. In cultured human astrocytes, adropin expression also declines with donor age. Additional analysis indicated positive correlations between adropin and transcriptomic signatures of energy metabolism and protein synthesis that are adversely affected by donor age. Adropin expression is also suppressed by pro-inflammatory factors. Collectively, these data indicate low circulating adropin levels are a potential early risk indicator of cognitive impairment. Declining adropin expression in the brain is a plausible link between aging, neuroinflammation, and risk of cognitive decline.

Dehydroepiandrosterone for depressive symptoms: A systematic review and meta-analysis of randomized controlled trials

Depression is a mental disorder that affects millions of people around the world. However, depressive symptoms can be seen in other psychiatric and medical conditions. Here, we investigate the effect of DHEA treatment on depressive symptoms in individuals with depression and/or other clinical conditions in which depressive symptoms are present. An electronic search was performed until October 2019, with no restrictions on language or year of publication in the following databases: Medline, EMBASE, LILACS, and Cochrane Library. Randomized controlled trials comparing DHEA versus placebo were included if the depressive symptoms were assessed. Fifteen studies with 853 female and male individuals were included in this review. To conduct the meta-analysis, data were extracted from 14 studies. In comparison with placebo, DHEA improved depressive symptoms (standardized mean difference [SMD] -0.28, 95% (CI) -0.45 to -0.11, p =.001, 12 studies, 742 individuals (375 in the experimental group and 367 in the placebo group), I2  = 24%), very low quality of evidence, 2 of 14 studies reporting this outcome were removed in a sensitivity analysis as they were strongly influencing heterogeneity between studies. No hormonal changes that indicated any risk to the participants' health were seen. Side effects observed were uncommon, mild, and transient, but commonly related to androgyny. In conclusion, DHEA was associated with a beneficial effect on depressive symptoms compared to placebo. However, these results should be viewed with caution, since the quality of evidence for this outcome was considered very low according to the GRADE criteria.

Dehydroepiandrosterone, Its Sulfate and Cognitive Functions

To present a review of cross-sectional and longitudinal studies that investigate the relationship between the hormones Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone sulfate (DHEA-S) and cognition. Methods: The cognition items included in this review were global cognitive function, memory, attention, executive function, intelligence, perception and visuospatial ability. A systematic review was proceeded using three databases: PubMed, ISI Web of Science, and PsycINFO. Results: Two thousand fifty five references about cognition and hormones were found; 772 duplicated references were excluded, resulting in 1.283 references to be evaluated. According to exclusion and inclusion criteria, 25 references were selected. A positive correlation between DHEA-S blood levels and global cognition was found in women and men. Other positive correlations between DHEA-S and working memory, attention and verbal fluency were found only in women. The DHEA effect on cognition is limited to one study conducted among young men with high-doses.

Hypothalamic-pituitary-adrenal (HPA) axis and aging

Human aging is associated with increasing frailty and morbidity which can result in significant disability. Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis may contribute to aging-related diseases like depression, cognitive deficits, and Alzheimer's disease in some older individuals. In addition to neuro-cognitive dysfunction, it has also been associated with declining physical performance possibly due to sarcopenia. This article reviews the pathophysiology of HPA dysfunction with respect to increased basal adrenocorticotropic hormone (ACTH) and cortisol secretion, decreased glucocorticoid (GC) negative feedback at the level of the paraventricular nucleus (PVN) of the hypothalamus, hippocampus (HC), and prefrontal cortex (PFC), and flattening of diurnal pattern of cortisol release. It is possible that the increased cortisol secretion is secondary to peripheral conversion from cortisone. There is a decline in pregnolone secretion and C-19 steroids (DHEA) with aging. There is a small decrease in aldosterone with aging, but a subset of the older population have a genetic predisposition to develop hyperaldosteronism due to the increased ACTH stimulation. The understanding of the HPA axis and aging remains a complex area with conflicting studies leading to controversial interpretations.

A systematic review of the evidence that brain structure is related to muscle structure and their relationship to brain and muscle function in humans over the lifecourse

BACKGROUND

An association between cognition and physical function has been shown to exist but the roles of muscle and brain structure in this relationship are not fully understood. A greater understanding of these relationships may lead to identification of the underlying mechanisms in this important area of research. This systematic review examines the evidence for whether: a) brain structure is related to muscle structure; b) brain structure is related to muscle function; and c) brain function is related to muscle structure in healthy children and adults.

METHODS

Medline, Embase, CINAHL and PsycINFO were searched on March 6th 2014. A grey literature search was performed using Google and Google Scholar. Hand searching through citations and references of relevant articles was also undertaken.

RESULTS

53 articles were included in the review; mean age of the subjects ranged from 8.8 to 85.5 years old. There is evidence of a positive association between both whole brain volume and white matter (WM) volume and muscle size. Total grey matter (GM) volume was not associated with muscle size but some areas of regional GM volume were associated with muscle size (right temporal pole and bilateral ventromedial prefrontal cortex). No evidence was found of a relationship between grip strength and whole brain volume however there was some evidence of a positive association with WM volume. Conversely, there is evidence that gait speed is positively associated with whole brain volume; this relationship may be driven by total WM volume or regional GM volumes, specifically the hippocampus. Markers of brain ageing, that is brain atrophy and greater accumulation of white matter hyperintensities (WMH), were associated with grip strength and gait speed. The location of WMH is important for gait speed; periventricular hyperintensities and brainstem WMH are associated with gait speed but subcortical WMH play less of a role. Cognitive function does not appear to be associated with muscle size.

CONCLUSION

There is evidence that brain structure is associated with muscle structure and function. Future studies need to follow these interactions longitudinally to understand potential causal relationships.

Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review

Changing demographics make it ever more important to understand the modifiable risk factors for disability and loss of independence with advancing age. For more than two decades there has been increasing interest in the role of sarcopenia, the age-related loss of muscle or lean mass, in curtailing active and healthy aging. There is now evidence to suggest that lack of strength, or dynapenia, is a more constant factor in compromised wellbeing in old age and it is apparent that the decline in muscle mass and the decline in strength can take quite different trajectories. This demands recognition of the concept of muscle quality; that is the force generating per capacity per unit cross-sectional area (CSA). An understanding of the impact of aging on skeletal muscle will require attention to both the changes in muscle size and the changes in muscle quality. The aim of this review is to present current knowledge of the decline in human muscle mass and strength with advancing age and the associated risk to health and survival and to review the underlying changes in muscle characteristics and the etiology of sarcopenia. Cross-sectional studies comparing young (18–45 years) and old (>65 years) samples show dramatic variation based on the technique used and population studied. The median of values of rate of loss reported across studies is 0.47% per year in men and 0.37% per year in women. Longitudinal studies show that in people aged 75 years, muscle mass is lost at a rate of 0.64–0.70% per year in women and 0.80–00.98% per year in men. Strength is lost more rapidly. Longitudinal studies show that at age 75 years, strength is lost at a rate of 3–4% per year in men and 2.5–3% per year in women. Studies that assessed changes in mass and strength in the same sample report a loss of strength 2–5 times faster than loss of mass. Loss of strength is a more consistent risk for disability and death than is loss of muscle mass.

Testosterone is not associated with mortality in older African-American males

INTRODUCTION. Although testosterone and its association with disease progression and mortality is a widely studied topic, no studies have evaluated mortality risks related to testosterone levels in an older African-American population. The mechanisms for known racial differences in mortality risk for certain cancers and cardiovascular risk factors are largely unknown. Elucidating a mortality risk associated with testosterone levels may give insight into the elevated risk for certain diseases in African-Americans. METHODS AND RESULTS. Study data were derived from a cohort 622 African-Americans (age 80.05  ±  6.4, range 68-102) from Saint Louis, Missouri that includes 190 males (age 79.38  ±  6.2, range 70-102). The eligible sample for this report includes 56 of the 190 males (age 78.89  ±  6.9, range 70-102) who donated blood at baseline in 1992-1994 and subsequently tested for total testosterone and bioavailable testosterone. Covariates for adjusted analyses were lower body functional limitations, physician visits and comorbidities, also collected at baseline. Males' mean bioavailable testosterone levels (ng/dl) were 33.33  ±  24.4 (n above 70 ng/dl = 5) and mean total testosterone levels (ng/dl) were 246.63  ±  118.7 (n above 300 ng/dl = 20). Vital status was determined through 2002; 41 males (73%) were deceased and 15 were alive. Mortality did not differ among males with testosterone levels <300 versus 300+ (p = 0.42) or with bioavailable testosterone levels <70 versus > 70 (p  =  0.34). Total testosterone levels did not predict mortality when adjusted for age (Adjusted Hazard Ratio [AHR] = 0.998; 95% confidence interval [CI] 0.995-1.001; p = 0.28) or adjusted for age and other covariates (AHR  =  0.099; 95% CI 0.996, 1.002; p  =  0.35). Bioavailable testosterone levels did not predict mortality when adjusted for age (AHR  =  0.992; 95% CI .977-1.007; p  =  0.30) or when adjusted for age and other covariates (AHR 0.991; 95% CI .976-1.006; p  =  0.261). CONCLUSION. In older African-American males, total and bioavailable testosterone levels, with and without adjustment for covariates, are not independently associated with mortality risk.

Relationships of total adiponectin and molecular weight fractions of adiponectin with free testosterone in African men and premenopausal women

Adiponectin, a protein secreted by adipose tissue, has anti-inflammatory, antithrombogenic, and antidiabetogenic effects. Lower plasma adiponectin levels are present in diabetes, obesity, and the metabolic syndrome. Adiponectin levels are higher in women compared with men. The purpose of this study was to determine whether there is a relationship between total adiponectin, or the molecular weight fractions of adiponectin, and testosterone levels in African American men and premenopausal women. A sample (N=48) of men and premenopausal women was selected based on high and low serum-free testosterone level. All patients had data on blood pressure, metabolic risk factors, and sex hormone levels. Stored plasma samples were assayed for total adiponectin. Molecular weight fractions of adiponectin were separated by gel electrophoresis and quantified by Western blot. Data analysis compared adiponectin (total and fractions) levels with androgen status in both sexes. Among men with high testosterone levels, all fractions of adiponectin were significantly lower than those in men with low testosterone (P<.05). In women with high testosterone, total adiponectin (P=.02) and all fractions of molecular weight adiponectin (P<.05) were lower compared with those in women with low testosterone. Plasma adiponectin levels are lower in both men and premenopausal women with relatively higher testosterone levels.

Concurrent change in dehydroepiandrosterone sulfate and functional performance in the oldest old: results from the Cardiovascular Health Study All Stars study

INTRODUCTION

The correlation between dehydroepiandrosterone sulfate (DHEAS) decline and age led to the hypothesis that DHEAS might be a marker of primary aging, though conflicting data from observational studies of mortality do not support this. We evaluated concurrent DHEAS and functional decline in a very old cohort to test if DHEAS change tracks with functional change during aging.

METHODS

DHEAS and functional performance (gait speed, grip strength, Modified Mini-Mental State Examination [3MSE] score, and digit symbol substitution test [DSST] score) were measured in 1996-1997 and 2005-2006 in 989 participants in the Cardiovascular Health Study All Stars study (mean age 85.2 years in 2005-2006, 63.5% women and 16.5% African American). We used multivariable linear regression to test the association of DHEAS decline with functional decline.

RESULTS

After adjustment, each standard deviation decrease in DHEAS was associated with greater declines in gait speed (0.12 m/s, p = .01), grip strength (0.09 kg, p = .03), 3MSE score (0.13 points, p < .001), and DSST score (0.14 points, p = .001) in women only. Additional adjustment for baseline DHEAS attenuated the association with grip strength but did not alter other estimates appreciably, and baseline DHEAS was unassociated with functional decline.

CONCLUSIONS

In this cohort of very old individuals, DHEAS decline tracked with declines in gait speed, 3MSE score, and DSST score, but not grip strength, in women independent of baseline DHEAS level. DHEAS decline might be a marker for age-associated performance decline, but its relevance is specific to women.