Associations of Bioavailable Serum Testosterone With Cognitive Function in Older Men: Results From the National Health and Nutrition Examination Survey

Relationship Between Sleep Duration and Cognitive Function in Older Adults: Analysis of NHANES and UK Biobank GWAS Data

OBJECTIVES

To explore the relationship between sleep duration and cognitive functions in older adults using NHANES, a national US population study dataset, and to explore the causal association with Mendelian randomization (MR) using the UK Biobank.

METHODS

First, an observational study was conducted with the NHANES database with participants ≥60 years. Sleep duration was measured with accelerometers for 7 consecutive days. Participants were divided into habitual short sleep (<7 h) and long sleep (>9 h) groups. Cognitive functions were measured with the CERAD Word Learning sub-set, Animal Fluency, and Digit Symbol Substitution test (DSST). Multivariate regression models were used to explore relationships between sleep duration and cognitive functions. Second, bidirectional MR was conducted with data for self-reported sleep duration, which came from a genome-wide association study (GWAS) comprising 446,118 adults from the UK Biobank, and general cognitive performance, which was obtained from a recent GWAS study (N = 257,841). Inverse-variance weighted (IVW) was used as the primary estimation of the outcome.

RESULTS

In the observational study, 2687 participants were included. Sleep duration was associated with cognitive functions in a non-linear way. Habitual long sleep (>9°h) was associated with lower scores on DSST (OR = 0.01, p = .003) in the fully-adjusted model. The association between habitual short sleep and cognitive functions was insignificant. For the MR, genetically predicted lower general cognitive performance was causally associated with a higher prevalence of habitual short sleep (OR = 0.97, p = 5.1 × 10-7) and long sleep (OR = 0.97, p = 8.87 × 10-16).

DISCUSSION

Short and long sleep duration might be both causally associated with worse outcomes of cognitive functions in older adults, highlighting the importance of maintaining sleep health.

Association between serum 25-hydroxyvitamin D3 level and cognitive impairment in older chronic kidney disease patients

This study aims to examine whether hypovitaminosis D was associated with cognitive impairment among chronic kidney patients with different level of albuminuria. This population-based cross-sectional study was conducted on elderly (over 60 years old) with urine albumin to creatinine ratio (UACR) ≥ 30 mg/g from 2011 to 2014 in the US National Health and Nutrition Examination Survey (NHANES). Cognitive function was assessed by the Consortium to Establish a Registry for Alzheimer's Disease Word List Learning (CERAD). Subjects were divided into 2 groups according to the absence or presence of cognitive impairment and a propensity score matching (PSM) was further conducted. The association was assessed with Spearman correlation and logistic regression analysis. The positive association of 25-hydroxyvitamin D3 (25(OH)D3) and cognitive score was presented. PSM analysis revealed that a higher level of 25(OH)D3 correlated to a better cognitive function in CKD patients with albuminuria, especially in patients with 30 mg/g ≤ UACR < 300 mg/g. This study indicated that a low 25(OH)D3 level was associated with poor cognitive performance, especially in patients with microalbuminuria. Thus, early diagnosis of vitamin D insufficiency and an effective intervention might be a useful therapeutic strategy to prevent cognitive decline in patients with the progression of renal dysfunction.

Handgrip strength is associated with cognitive function in older patients with stage 3-5 chronic kidney disease: results from the NHANES

In this study, we aimed to investigate the association between handgrip strength (HGS) and cognitive performance in stage 3-5 chronic kidney disease (CKD) patients aged ≥ 60 years. This cross-sectional study analyzed data from National Health and Nutrition Examination Survey (NHANES) database 2011-2014. Three tests were used to assess the cognitive performance, including consortium to establish a registry for Alzheimer's disease (CERAD), animal fluency test (AFT), and digit symbol substitution test (DSST). The multivariate linear regression analyses adjusting for confounding factors were utilized to evaluate the association of HGS with cognitive performance. A total of 678 older stage 3-5 CKD patients were included in this study. After adjusting for multiple factors, a higher HGS was positively associated with a higher CERAD-delayed recall and DSST score. In addition, our analysis indicated that HGS probably correlated with better performance of immediate learning ability in male, while working memory, sustained attention, and processing speed in female. HGS may be an important indicator for cognitive deficits in stage 3-5 CKD patients, especially for learning ability and executive function. Further research to explore the sex-specific and domain-specific and possible mechanisms are required.

Association between visceral adipose tissue and total testosterone among the United States male adults: a cross-sectional study

Visceral adipose tissue (VAT) is regarded as an important risk factor for obesity-related diseases. The results of the association between VAT and total testosterone (TT) are controversial and whether this association is nonlinear is still unknown. 3971 male participants who were aged 20-59 years from the National Health and Nutrition Examination Surveys 2011-2016 were included. VAT area was measured by dual-energy x-ray absorptiometry. TT in serum was assessed utilizing the isotope dilution liquid chromatography-tandem mass spectrometry technique. Linear regression models assessed the associations between VAT area and TT. A restricted cubic spline model was employed to investigate nonlinear relationships. A two-piecewise linear regression model was applied to determine the threshold effect. Subgroup analyses were conducted. The weighted methods were utilized in all analyses. VAT area was inversely associated with TT in the crude and adjusted models. In the fully adjusted model, VAT area was associated with TT (β = -0.59, 95% confidence interval [CI] = -0.74, -0.43) and compared to the first tertile of VAT area, the second and the third tertile had a lower TT level, the β and 95% CI = -65.49 (-83.72, -47.25) and -97.57 (-121.86, -73.27) respectively. We found these inverse associations were nonlinear. The cutoff point of the VAT area was 126 cm2. When the VAT area was <126 cm2, VAT area was significantly associated with a lower TT level (β = -1.55, 95% CI = -1.93 to -1.17, p < 0.0001). However, when the VAT area was ≥126 cm2, this association was less apparent (β = -0.26, 95% CI = -0.52 to 0.01, p = 0.06). No significant interactions among different ages (<50 or ≥50 years), marital, and physical activity status were found. These findings underscore the potential for VAT area as a modifiable indicator for improving testosterone deficiency.

Addressing cancer anorexia-cachexia in older patients: Potential therapeutic strategies and molecular pathways

Cancer cachexia (CC) syndrome, a feature of cancer-associated muscle wasting, is particularly pronounced in older patients, and is characterised by decreased energy intake and upregulated skeletal muscle catabolic pathways. To address CC, appetite stimulants, anabolic drugs, cytokine mediators, essential amino acid supplementation, nutritional counselling, cognitive behavioural therapy, and enteral nutrition have been utilised. However, pharmacological treatments that have also shown promising results, such as megestrol acetate, anamorelin, thalidomide, and delta-9-tetrahydrocannabinol, have been associated with gastrointestinal and cardiovascular complications. Emerging evidence on the efficacy of probiotics in modulating gut microbiota also presents a promising adjunct to traditional therapies, potentially enhancing nutritional absorption and systemic inflammation control. Additionally, low-dose olanzapine has demonstrated improved appetite and weight management in older patients undergoing chemotherapy, offering a potential refinement to current therapeutic approaches. This review aims to elucidate the molecular mechanisms underpinning CC, with a particular focus on the role of anorexia in exacerbating muscle wasting, and to propose pharmacological and non-pharmacological strategies to mitigate this syndrome, particularly emphasising the needs of an older demographic. Future research targeting CC should focus on refining appetite-stimulating drugs with fewer side-effects, specifically catering to the needs of older patients, and investigating nutritional factors that can either enhance appetite or minimise suppression of appetite in individuals with CC, especially within this vulnerable group.

Androgen Deprivation Therapy for Prostate Cancer: Focus on Cognitive Function and Mood

Prostate cancer is the second leading cause of cancer death in men in the United States. Androgen deprivation therapy (ADT) is currently the primary treatment for metastatic prostate cancer, and some studies have shown that the use of anti-androgen drugs is related to a reduction in cognitive function, mood changes, diminished quality of life, dementia, and possibly Alzheimer's disease. ADT has potential physiological effects such as a reduction in white matter integrity and a negative impact on hypothalamic functions due to the lowering of testosterone levels or the blockade of downstream androgen receptor signaling by first- and second-generation anti-androgen drugs. A comparative analysis of prostate cancer patients undergoing ADT and Alzheimer patients identified over 30 shared genes, illustrating common ground for the mechanistic underpinning of the symptomatology. The purpose of this review was to investigate the effects of ADT on cognitive function, mood, and quality of life, as well as to analyze the relationship between ADT and Alzheimer's disease. The evaluation of prostate cancer patient cognitive ability via neurocognitive testing is described. Future studies should further explore the connection among cognitive deficits, mood disturbances, and the physiological changes that occur when hormonal balance is altered.

Dietary Acid Load Is Not Associated with Serum Testosterone in Men: Insights from the NHANES

The dietary acid load (DAL) is a novel marker of overall diet quality, which has been associated with overweight, type 2 diabetes and altered glucocorticoid secretion. A potential association with sex hormones is thus not inconceivable. We investigated whether DAL was associated with serum total testosterone concentrations of men in the National Health and Nutrition Examination Survey. The DAL scores, including the potential renal acid load (PRAL) and net endogenous acid production (NEAP), were estimated and compared between participants with low and normal testosterone levels. The investigated sample encompassed n = 377 males with a mean age of 49.50 years. Approximately 73% of the sample were of Non-Hispanic White origin. None of the examined DAL scores showed significant associations with serum testosterone levels. We observed no significant differences in the crude DAL scores between individuals with low testosterone levels and individuals with normal testosterone levels. Multivariate regression models adjusting for covariates confirmed the lack of associations between the PRAL and serum testosterone. Our results are of particular importance for those individuals who wish to lower their DAL in light of the presumable health effects of a more alkaline diet. Our data suggest that diet modifications toward a lower intake of animal protein and refined grains (which consecutively translates into a lower DAL) may not negatively affect men's testosterone levels.

Handgrip strength is associated with learning and verbal fluency in older men without dementia: insights from the NHANES

Low handgrip strength, a hallmark measure of whole-body strength, has been linked with greater odds of cognitive decline and dementia; however, conflicting findings, which could be due to population characteristics and choice of tools, such for the assessment of handgrip strength and cognitive function domains, also exist. Therefore, we examined the relationship of handgrip strength with a comprehensive list of tests to assess domains of cognitive function using a representative sample of US older men and women without neurodegenerative disorders such as dementia. We analyzed cross-sectional data from the US National Health and Nutrition Examination Survey (NHANES) between 2011 and 2014, with a study cohort of 777 older adults (380 men and 397 women) above 60 years of age. Handgrip strength was assessed using a handgrip dynamometer, while cognitive function was assessed through the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Learning Test (WLLT), Word List Recall Test (WLRT), Intrusion Word Count Test (WLLT-IC and WLRT-IC), the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST). Sex-stratified multiple linear regression analyses were performed upon covariate adjustment for age, ethnicity, socio-economic status, education, medical history, body mass index, physical activity, energy, protein, and alcohol intake. Maximal handgrip strength was positively associated with cognitive function scores, including CERAD WLLT (P = 0.009, R² = 0.146) and AFT (P = 0.022, R² = 0.024) in older men, but not in women (CERAD WLLT: P = 0.253, AFT: P = 0.370). No significant associations with CERAD WLLRT (men: P = 0.057, women: P = 0.976), WLLT-IC (men: P = 0.671, women: P = 0.869), WLLRT-IC (men: P = 0.111, women: P = 0.861), and DSST (men: P = 0.108, women: P = 0.091) were observed. Dose-response curves exhibited a prominent linear relationship between all significant associations after covariate adjustment, with no indication of a plateau in these relationships. In conclusion, higher handgrip strength was independently associated with better learning ability for novel verbal information and verbal fluency in US men over the age of 60 and without dementia. Longitudinal studies are required to confirm whether muscle strength independently predicts cognitive function changes in older adults in a sex-specific manner, and whether this connection is affirmed to the possibility of reverse causation due to declines in physical activity levels in the preclinical phase of dementia.