Associations of blood cell indices and anemia with risk of incident dementia: A prospective cohort study of 313,448 participants

Abstract

IntroductionLow hemoglobin and anemia are associated with cognitive impairment and Alzheimer's disease (AD). However, the associations of other blood cell indices with incident dementia risk and the underlined mechanisms are unknown.MethodsThree hundred thirteen thousand four hundred forty‐eight participants from the UK Biobank were included. Cox and restricted cubic spline models were used to investigate linear and non‐linear longitudinal associations. Mendelian randomization analysis was used to identify causal associations. Linear regression models were used to explore potential mechanisms driven by brain structures.ResultsDuring a mean follow‐up of 9.03 years, 6833 participants developed dementia. Eighteen indices were associated with dementia risk regarding erythrocytes, immature erythrocytes, and leukocytes. Anemia was associated with a 56% higher risk of developing dementia. Hemoglobin and red blood cell distribution width were causally associated with AD. Extensive associations exist between most blood cell indices and brain structures.DiscussionThese findings consolidated associations between blood cells and dementia.Highlight Anemia was associated with 56% higher risk for all‐cause dementia. Hematocrit percentage, mean corpuscular volume, platelet crit, and mean platelet volume had U‐shaped associations with incident dementia risk. Hemoglobin (HGB) and red blood cell distribution width had causal effects on Alzheimer's risk. HGB and anemia were associated with brain structure alterations.

Graph Theory Further Revealed Visual Spatial Working Memory Impairment in Patients with Inflammatory Bowel Disease

“…Additionally, RDW has been applied in predicting cognitive impairment 52 and dementia. 53 The correlation between peripheral inflammation and cognitive impairment has been confirmed. 54 Importantly, previous studies suggest that intestinal inflammation can induce spatial object recognition and spatial memory impairments through the activation of inflammatory factors.…”

Examining the Role of a Functional Deficiency of Iron in Lysosomal Storage Disorders with Translational Relevance to Alzheimer’s Disease

“…For instance, in type I Gaucher's disease, some pediatric patients may develop anemia [137], and patients with Niemann-Pick type C1 disease can display hematological alterations, implicating a dysregulation of iron homeostasis [93]. Meanwhile, a large prospective study related to Alzheimer's disease found that anemia elevated the risk for dementia by 56% [189]. Although the brain may preferentially attempt to acquire iron at the expense of other organ systems, particularly during development [190], too little iron can impair normal brain development [23,[140][141][142][143][144].…”

“Association of blood cell indices and anemia with risk of incident dementia”: Missing important covariates in MRI analysis may be misleading

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This letter is in response to "Associations of blood cell indices and anemia with risk of incident dementia: A prospective cohort study of 313,448 participants" by Qiang and colleagues. 1 Brain magnetic resonance imaging (MRI) is an important tool for understanding brain structure, offering an opportunity to evaluate the possible mechanisms underlying dementia progression. 2,3 In their recent article, Qiang and colleagues assessed associations of blood cell indices and anemia with the risk of dementia and brain MRI measures.

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