The Impact of Antiplatelet Use on the Risk of Intracerebral Hemorrhage in Patients with Alzheimer's Disease: A Nationwide Cohort Study

Alterations in the Processing of Platelet APP (Amyloid Beta Precursor Protein) in Alzheimer Disease: The Possible Nexus

Alzheimer's disease (AD) is the most common neurodegenerative disease associated with the development of dementia. The hallmarks of AD neuropathology are accumulations of amyloid peptide (Aβ) and neurofibrillary tangles (NFTs). Aβ is derived from the processing of APP (amyloid beta precursor protein) by BACE1 (beta-secretase 1) and γ-secretase through an amyloidogenic pathway. However, processing of APP by ADAM10/α-secretase (ADAM metallopeptidase domain 10) enzymes through a non-amyloidogenic pathway produces soluble APP alpha (sAPPα), which has a neuroprotective effect. It has been shown that activated platelets are implicated in the pathogenesis of AD, which also increases platelet activation. Under physiological conditions, platelets regulate synaptic plasticity and increase neuronal differentiation by regulation of the inflammatory response. However, overactivated platelets contribute to the pathogenesis of AD. Activated platelets represent the main source of circulating APP and Aβ that may be involved in AD neuropathology. Therefore, there is a close relationship between AD neuropathology and activated platelets. This review discusses the potential role of platelets in the pathogenesis of AD, and how targeting of activated platelets may reduce AD neuropathology.

Early Antiplatelet Resumption and the Risks of Major Bleeding After Intracerebral Hemorrhage

BACKGROUND

The appropriate timing of resuming antithrombotic therapy after intracerebral hemorrhage (ICH) remains unclear. The aim of this study was to compare the risks of major bleeding between early and late antiplatelet resumption in ICH survivors.

METHODS

Between 2008 and 2017, ICH patients were available in the National Health Insurance Research Database. Patients with a medication possession ratio of antiplatelet treatment ≥50% before ICH and after antiplatelet resumption were screened. We excluded patients with atrial fibrillation, heart failure, under anticoagulant or hemodialysis treatment, and developed cerebrovascular events or died before antiplatelet resumption. Finally, 1584 eligible patients were divided into EARLY (≤30 days) and LATE groups (31-365 days after the index ICH) based on the timing of antiplatelet resumption. Patients were followed until the occurrence of a clinical outcome, end of 1-year follow-up, death, or until December 31, 2018. The primary outcome was recurrent ICH. The secondary outcomes included all-cause mortality, major hemorrhagic events, major occlusive vascular events, and ischemic stroke. Cox proportional hazard model after matching was used for comparison between the 2 groups.

RESULTS

Both the EARLY and LATE groups had a similar risk of 1-year recurrent ICH (EARLY versus LATE: 3.12% versus 3.27%; adjusted hazard ratio [AHR], 0.967 [95% CI, 0.522-1.791]) after matching. Both groups also had a similar risk of each secondary outcome at 1-year follow-up. Subgroup analyses disclosed early antiplatelet resumption in the patients without prior cerebrovascular disease were associated with lower risks of all-cause mortality (AHR, 0.199 [95% CI, 0.054-0.739]) and major hemorrhagic events (AHR, 0.090 [95% CI, 0.010-0.797]), while early antiplatelet resumption in the patients with chronic kidney disease were associated with a lower risk of ischemic stroke (AHR, 0.065 [95% CI, 0.012-0.364]).

CONCLUSIONS

Early resumption of antiplatelet was as safe as delayed antiplatelet resumption in ICH patients. Besides, those without prior cerebrovascular disease or with chronic kidney disease may benefit more from early antiplatelet resumption.

Incident stroke in patients with Alzheimer's disease: systematic review and meta-analysis

Vascular mechanisms are increasingly recognized in the pathophysiology of Alzheimer's disease (AD), but less is known about the occurrence of stroke in AD patients. We aimed to quantify the risk of stroke in patients with AD and compare the incidence rates (IR) of stroke in individuals without AD. Systematic search of Embase and MEDLINE between 1970 and 2020. Inclusion criteria: reports with ≥ 50 patients with non-familial AD, which reported the occurrence of stroke (all types) and/or ischemic stroke and/or intracerebral hemorrhage (ICH) during follow-up. Meta-analyses of pooled data using random-effects model were performed. IR were calculated for each study. Incidence rate ratios (IRR) were calculated for studies presenting a control-group without AD. Among 5109 retrieved studies, 29 (0.6%) fulfilled the inclusion criteria, reporting a total of 61,824 AD patients. In AD patients the IR were 15.4/1000 person-years for stroke (all types), 13.0/1000 person-years for ischemic stroke and 3.4/1000 person-years for ICH. When compared to controls without AD, incidence rate for ICH in AD patients was significantly higher (IRR = 1.67, 95%CI 1.43-1.96), but similar for ischemic stroke. Incident stroke is not a rare event in AD population. AD is associated with an increased risk of intracerebral hemorrhage which warrants further clarification.

Aspirin in people with dementia, long-term benefits, and harms: a systematic review

PURPOSE

People with dementia may have indications for aspirin prescription and clinicians are asked to balance the potential risks against benefits. This review examines the evidence for the risk and benefit of long-term aspirin use in people with dementia aged over 65 years, including randomised controlled trials and observational studies.

METHODS

We searched three databases for research published between 2007 and 2020. Each eligible article was assessed for risk of bias, and confidence in findings was rated using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Four papers met inclusion criteria: one randomised controlled trial, two cohort studies, and one with pooled data. All looked only at dementia of Alzheimer's type, and none addressed myocardial or cerebral infarction as outcomes. Dementia progression was reported by two studies, with conflicting results. The trial found no significant effect of aspirin on mortality (odds ratio aspirin vs. no aspirin 1.07, 95% confidence interval 0.58-1.97) but found more events of severe bleeding with aspirin (OR aspirin vs. no aspirin 6.9, 1.5-31.2). An excess in intracranial haemorrhage in the aspirin group was judged plausible based on two non-randomised studies.

CONCLUSIONS

The review findings are limited because studies include only people with Alzheimer's-type dementia and lack confirmatory studies, although an increased risk of bleeding events is recognised. Further research that addresses the benefits and risks of aspirin in more representative groups of people with dementia is needed to guide prescribing decisions.

Telmisartan use and risk of dementia in type 2 diabetes patients with hypertension: A population-based cohort study

BACKGROUND

Angiotensin receptor blockers (ARBs) may have protective effects against dementia occurrence in patients with hypertension (HTN). However, whether telmisartan, an ARB with peroxisome proliferator-activated receptor γ (PPAR-γ)-modulating effects, has additional benefits compared to other ARBs remains unclear.

METHODS AND FINDINGS

Between 1997 and 2013, 2,166,944 type 2 diabetes mellitus (T2DM) patients were identified from the National Health Insurance Research Database of Taiwan. Patients with HTN using ARBs were included in the study. Patients with a history of stroke, traumatic brain injury, or dementia were excluded. Finally, 65,511 eligible patients were divided into 2 groups: the telmisartan group and the non-telmisartan ARB group. Propensity score matching (1:4) was used to balance the distribution of baseline characteristics and medications. The primary outcome was the diagnosis of dementia. The secondary outcomes included the diagnosis of Alzheimer disease and occurrence of symptomatic ischemic stroke (IS), any IS, and all-cause mortality. The risks between groups were compared using a Cox proportional hazard model. Statistical significance was set at p < 0.05. There were 2,280 and 9,120 patients in the telmisartan and non-telmisartan ARB groups, respectively. Patients in the telmisartan group had a lower risk of dementia diagnosis (telmisartan versus non-telmisartan ARBs: 2.19% versus 3.20%; HR, 0.72; 95% CI, 0.53 to 0.97; p = 0.030). They also had lower risk of dementia diagnosis with IS as a competing risk (subdistribution HR, 0.70; 95% CI, 0.51 to 0.95; p = 0.022) and with all-cause mortality as a competing risk (subdistribution HR, 0.71; 95% CI, 0.53 to 0.97; p = 0.029). In addition, the telmisartan users had a lower risk of any IS (6.84% versus 8.57%; HR, 0.79; 95% CI, 0.67 to 0.94; p = 0.008) during long-term follow-up. Study limitations included potential residual confounding by indication, interpretation of causal effects in an observational study, and bias caused by using diagnostic and medication codes to represent real clinical data.

CONCLUSIONS

The current study suggests that telmisartan use in hypertensive T2DM patients may be associated with a lower risk of dementia and any IS events in an East-Asian population.