Association Between Anemia and Dementia: A Nationwide, Populationbased Cohort Study in Taiwan

Lower cognitive function as a risk factor for anemia among older Japanese women from the longitudinal observation in the SONIC study

AIM

The aging-related increase in the incidence of anemia potentially affects the mortality risk. Lower cognitive function is common among older adults, and anemia is one of the causes of cognitive decline. However, to the best of our knowledge, no study has investigated whether cognitive decline is a risk factor for anemia in older people. Therefore, in this study, we used a 3-year longitudinal evaluation to examine the association of cognitive function with anemia in community-dwelling older adults.

METHODS

This longitudinal study enrolled participants without anemia (diagnosed based on the World Health Organization's criteria) at baseline. Cognitive function was assessed using the Japanese version of the Montreal Cognitive Assessment. Multiple logistic regression models were used to examine the association between cognitive function at baseline and the presence of anemia 3 years later.

RESULTS

Participants were in the 69-71 and 79-81 years age groups, and 974 older people (48.6% men) were enrolled, of whom 126 (12.9%) had anemia after 3 years. After adjusting, cognitive function at baseline was associated with anemia in women, but not in men.

CONCLUSIONS

Older Japanese women with lower cognitive function have an increased risk for anemia 3 years later. The adoption of a lifestyle that utilizes or improves cognitive function might be important to prevent anemia in older women. Geriatr Gerontol Int 2023; ••: ••-••.

The Cause of Alzheimer's Disease: The Theory of Multipathology Convergence to Chronic Neuronal Stress

The field of Alzheimer's disease (AD) research critically lacks an all-inclusive etiology theory that would integrate existing hypotheses and explain the heterogeneity of disease trajectory and pathologies observed in each individual patient. Here, we propose a novel comprehensive theory that we named: the multipathology convergence to chronic neuronal stress. Our new theory reconsiders long-standing dogmas advanced by previous incomplete theories. Firstly, while it is undeniable that amyloid beta (Aβ) is involved in AD, in the seminal stage of the disease Aβ is unlikely pathogenic. Instead, we hypothesize that the root cause of AD is neuronal stress in the central nervous system (CNS), and Aβ is expressed as part of the physiological response to protect CNS neurons from stress. If there is no return to homeostasis, then Aβ becomes overexpressed, and this includes the generation of longer forms that are more toxic and prone to oligomerization. Secondly, AD etiology is plausibly not strictly compartmentalized within the CNS but may also result from the dysfunction of other physiological systems in the entire body. This view implies that AD may not have a single cause, but rather needs to be considered as a spectrum of multiple chronic pathological modalities converging to the persistent stressing of CNS neurons. These chronic pathological modalities, which include cardiovascular disease, metabolic disorders, and CNS structural changes, often start individually, and over time combine with other chronic modalities to incrementally escalate the amount of stress applied to CNS neurons. We present the case for considering Aβ as a marker of neuronal stress in response to hypoxic, toxic, and starvation events, rather than solely a marker of AD. We also detail numerous human chronic conditions that can lead to neuronal stress in the CNS, making the link with co-morbidities encountered in daily clinical AD practice. Finally, we explain how our theory could be leveraged to improve clinical care for AD and related dementia in personalized medicine paradigms in the near future.

Sex-Specific Associations of Dietary Iron Intake with Brain Iron Deposition on Imaging and Incident Dementia: A Prospective Cohort Study

OBJECTIVES

The study aimed to evaluate the association of dietary iron intake with incident dementia and brain iron deposition.

DESIGN/SETTING/PARTICIPANTS

We included dementia-free participants from the UK Biobank who completed at least one 24-hour dietary recall at study baseline (2009-2012) and were followed up to 2021. Incident dementia was determined through linkage to medical records and death registries. Brain MRI was conducted in a subgroup of participants since 2014, with T2* measurements being used as indicators of brain iron deposition.

MEASUREMENTS

Cox proportional hazard models were used to assess the associations of high (top quintile) and low (bottom quintile) versus medium (quintile 2 to 4) level of dietary iron intake with incident dementia, respectively. Linear regression was applied to assess the relations between dietary iron intake and brain T2* measurements.

RESULTS

During follow-up (mean = 9.5 years), a total of 1,454 participants (650 women and 804 men) developed dementia among 191,694 participants (55.0% female; mean age, 56.2 years). When adjusted for sociodemographic, lifestyle, and other dietary factors, participants with low dietary iron intake (< 10.05 mg/day) had a significantly higher dementia risk (hazard ratio [HR], 1.50, 95% confidence interval [CI], 1.19-1.89), while the relation for high intake (> 16.92 mg/day) was non-significant (HR, 1.16, 95% CI, 0.92-1.46). A significant gender difference (P-interaction < 0.001) was observed, with a U-shaped association in male participants (HR for low vs. medium, 1.56, 95% CI, 1.14-2.13; HR for high vs. medium, 1.39, 95% CI, 1.03 - 1.88; P-nonlinearity < 0.001) and no significant association in females, regardless of their menopause status. In general, dietary iron intake was not related to T2* measurements of iron deposition in most brain regions.

CONCLUSION

Our findings suggested a U-shape relationship between dietary iron intake and risk of dementia among males, but not females.

Red cell distribution width, anemia and their associations with white matter integrity among middle-aged urban adults

Anemia (blood hemoglobin [Hb] <13 g/dL among males; <12 g/dL among females) and elevated red cell distribution width (RDW) are potential risk factors for reduced brain white matter integrity (WMI), reflected by lower fractional anisotropy or increased mean diffusivity. Cross-sectional data with exposure-outcome lag time was used, whereby hematological exposures (RDW and Hb) and covariates were compiled from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study with available visit 1 (v1; 2004-2009) and/or v2 (2009-2013) data; while diffusion tensor magnetic resonance imaging (dMRI) outcome data were collected at HANDLS SCAN visit (vscan: 2011-2015, n = 214, mean follow-up from v1 ±SD: 5.6 ± 1.8 year). Multivariable-adjusted linear regression analyses were conducted, overall, stratifying by sex, and further restricting to the nonanemic for RDW exposures in part of the analyses. Among males, RDW(v1) was linked with lower global mean fractional anisotropy (standardized effect size b = -0.30, p= 0.003, q < 0.05; basic model), an association only slightly attenuated with further covariate adjustment. Anemia was not a risk factor for poor WMI, independently of RDW. Ultimately, pending further longitudinal evidence, initial RDW appears to be associated with poorer WMI among males.

New Drugs for Heart Failure: What is the Evidence in Older Patients?

Heart failure (HF) is a major public health concern, with a high prevalence in the older population. The majority of randomized clinical trials evaluating new emerging pharmacologic agents for HF (eg, angiotensin receptor-neprilysin inhibitors, sodium-glucose cotransporter 2 inhibitors, intravenous iron for deficiency treatment, transthyretin stabilizers, soluble guanylate cyclase stimulators, cardiac myosin activators, and new potassium binders) have found positive results on various clinical outcomes, particularly in patients with reduced ejection fraction. These treatments might have an important role in the management of older patients as well. Nevertheless, trials demonstrating benefit of these drugs have involved patients significantly younger (on average, approximately 10 years) and fewer comorbidities than those commonly encountered in clinical practice. We describe the recent evidence regarding the newest HF drugs and their applicability to older individuals in terms of efficacy and safety, and we discuss their effects on outcomes particularly valuable to older patients, such as preservation of cognitive function, functional status, independence, and quality of life. Although available subgroup analyses seem to confirm efficacy and safety across the age spectrum for some of these drugs, their effects on older patients centered outcomes often have been neglected. Future HF trials should be designed to include older patients more representative of the real clinical practice, to overcome generalizability biases.

Anemia and the Risk of Cognitive Impairment: An Updated Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment is one of the most common, burdensome, and costly disorders in the elderly worldwide. The magnitude of the association between anemia and overall cognitive impairment (OCI) has not been established.

OBJECTIVE

We aimed to update and expand previous evidence of the association between anemia and the risk of OCI.

METHODS

We conducted an updated systematic review and meta-analysis. We searched electronic databases, including EMBASE, PubMed, and Web of Science for published observational studies and clinical trials between 1 January 1990 and 1 June 2020. We excluded articles that were in the form of a review, letter to editors, short reports, and studies with less than 50 participants. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. We estimated summary risk ratios (RRs) with random effects.

RESULTS

A total of 20 studies, involving 6558 OCI patients were included. Anemia was significantly associated with an increased risk of OCI (adjusted RR (aRR) 1.39 (95% CI, 1.25-1.55; p < 0.001)). In subgroup analysis, anemia was also associated with an increased risk of all-cause dementia (adjusted RR (aRR), 1.39 (95% CI, 1.23-1.56; p < 0.001)), Alzheimer's disease [aRR, 1.59 (95% CI, 1.18-2.13; p = 0.002)], and mild cognitive impairment (aRR, 1.36 (95% CI, 1.04-1.78; p = 0.02)).

CONCLUSION

This updated meta-analysis shows that patients with anemia appear to have a nearly 1.39-fold risk of developing OCI than those without anemia. The magnitude of this risk underscores the importance of improving anemia patients' health outcomes, particularly in elderly patients.

Association of Antioxidant Vitamins A, C, E and Carotenoids with Cognitive Performance over Time: A Cohort Study of Middle-Aged Adults

Carotenoids may strengthen the association of antioxidant vitamins A, C, and E with favorable cognitive outcomes over time, though a few prospective studies have examined this hypothesis. We evaluated the longitudinal data from 1251 participants in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study (Age at visit 1 in 2004–2009 (v₁): 30–65 years). Vitamins A, C, and E dietary intakes and total and individual dietary carotenoids were computed using two 24-h recalls at v₁. Cognitive tests, covering global mental status and domains of memory/learning, attention, psychomotor speed, visuo-spatial, language/verbal, and executive function were conducted at v₁ and/or v₂ (2009–2013); mean ± SD follow-up: 4.66 ± 0.93 years. Mixed-effects linear regression models detected an interaction between vitamin E and total (and individual) carotenoids for three of 11 cognitive tests at v₁, with only one meeting the statistical significance upon multiple testing correction whereby vitamin E was linked with greater verbal memory performance in the uppermost total carotenoid tertile (γ_0a = +0.26 ± 0.08, p = 0.002), a synergism largely driven by carotenoid lycopene. Vitamins A and C showed no consistent interactions with carotenoids. In conclusion, we provide partial evidence for synergism between vitamin E and carotenoids in relation to better baseline cognitive performance, pending further studies with time-dependent exposures and randomized trials directly examining this synergism.

Association between Anemia and Stroke in Females: A Nationwide, Population-Based Cohort Study in Taiwan

Optimal stroke prevention strategies for women should take into account specific sex-related stroke risk factors. Anemia is a common medical condition in females, particularly in women of reproductive age. This study investigated whether anemia is an independent risk factor for stroke in females in a population-based cohort study. We investigated newly diagnosed anemic female patients with no history of central nervous system disease, psychiatric disorders, traumatic brain injury, major operations or hemorrhagic diseases identified from the Taiwan National Health Insurance Research Database. Non-anemic matched controls (1:1) were selected based on a propensity score estimated using a logistic regression model that included demographic characteristics and comorbidities. A competing risk analysis was applied to estimate the stroke risk in anemic patients compared to that of their matched controls. In our study, the adjusted sub-distribution hazard ratios (aSHRs) of overall, hemorrhagic and ischemic stroke in anemic female patients aged <50 years were 1.35 (95% confidence interval (CI): 1.19-1.52, p < 0.001), 1.31 (95% CI, 1.09-1.56, p < 0.003), and 1.35 (95% CI, 1.15-1.58, p < 0.001), respectively, compared to non-anemic female controls. However, a positive association between anemia and stroke was not found for those aged ≥50 years. Similar results were observed when the follow-up age was limited to 50 years to reduce the potential effects of menopause on stroke. In conclusion, the present population-based cohort study found that anemia is a potential risk factor for overall, hemorrhagic and ischemic stroke in females of reproductive age.