Design and Rationale for a Cognitive Outcome Substudy in Ischemic Stroke Patients with High Risk of Cerebral Hemorrhage

Antiplatelets and Vascular Dementia: A Systematic Review

Vascular dementia (VD) is a neurocognitive disorder whose precise definition is still up for debate. VD generally refers to dementia that is primarily caused by cerebrovascular disease or impaired cerebral blood flow. It is a subset of vascular cognitive impairment, a class of diseases that relate any cerebrovascular injury as a causal or correlating factor for cognitive decline, most commonly seen in the elderly. Patients who present with both cognitive impairment and clinical or radiologic indications of cerebrovascular pathology should have vascular risk factors, particularly hypertension, examined and treated. While these strategies may be more effective at avoiding dementia than at ameliorating it, there is a compelling case for intensive secondary stroke prevention in these patients. Repeated stroke is related to an increased chance of cognitive decline, and poststroke dementia is connected with an increased risk of death. In general, most physicians follow recommendations for secondary stroke prevention in patients with VD, which can be accomplished by the use of antithrombotic medicines such as antiplatelets (aspirin, clopidogrel, ticlopidine, cilostazol, etc.). In individuals with a high risk of atherosclerosis and those with documented symptomatic cerebrovascular illness, antiplatelets treatment lowers the risk of stroke. While this therapy strategy of prevention and rigorous risk management has a compelling justification, there is only limited and indirect data to support it. The following systematic review examines the role of antiplatelets in the management of vascular dementia in published clinical trials and studies and comments on the current evidence available to support their use and highlights the need for further study.

Antithrombotic therapy to prevent cognitive decline in people with small vessel disease on neuroimaging but without dementia

BACKGROUND

Cerebral small vessel disease is a progressive disease of the brain's deep perforating blood vessels. It is usually diagnosed based on lesions seen on brain imaging. Cerebral small vessel disease is a common cause of stroke but can also cause a progressive cognitive decline. As antithrombotic therapy is an established treatment for stroke prevention, we sought to determine whether antithrombotic therapy might also be effective in preventing cognitive decline in people with small vessel disease.

OBJECTIVES

To assess the effects of antithrombotic therapy for prevention of cognitive decline in people with small vessel disease on neuroimaging but without dementia.

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Review Group's Specialised Register, and the Cochrane Stroke Group's Specialised Register; the most recent search was on 21 July 2021. We also searched MEDLINE, Embase, four other databases and two trials registries. We searched the reference lists of the articles retrieved from these searches. As trials with a stroke focus may include relevant subgroup data, we complemented these searches with a focussed search of all antithrombotic titles in the Cochrane Stroke Group database.  SELECTION CRITERIA: We included randomised controlled trials (RCT) of people with neuroimaging evidence of at least mild cerebral small vessel disease (defined here as white matter hyperintensities, lacunes of presumed vascular origin and subcortical infarcts) but with no evidence of dementia. The trials had to compare antithrombotic therapy of minimum 24 weeks' duration to no antithrombotic therapy (either placebo or treatment as usual), or compare different antithrombotic treatment regimens. Antithrombotic therapy could include antiplatelet agents (as monotherapy or combination therapy), anticoagulants or a combination.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all the titles identified by the searches. We assessed full texts for eligibility for inclusion according to our prespecified selection criteria, extracted data to a proforma and assessed risk of bias using the Cochrane tool for RCTs. We evaluated the certainty of evidence using GRADE. Due to heterogeneity across included participants, interventions and outcomes of eligible trials, it was not possible to perform meta-analyses.

MAIN RESULTS

We included three RCTs (3384 participants). One study investigated the effect of antithrombotic therapy in participants not yet on antithrombotic therapy; two studies investigated the effect of additional antithrombotic therapy, one in a population already taking a single antithrombotic agent and one in a mixed population (participants on an antithrombotic drug and antithrombotic-naive participants). Intervention and follow-up durations varied from 24 weeks to four years. Jia 2016 was a placebo-controlled trial assessing 24 weeks of treatment with DL-3-n-butylphthalide (a compound with multimodal actions, including a putative antiplatelet effect) in 280 Chinese participants with vascular cognitive impairment caused by subcortical ischaemic small vessel disease, but without dementia. There was very low-certainty evidence for a small difference in cognitive test scores favouring treatment with DL-3-n-butylphthalide, as measured by the 12-item Alzheimer's Disease Assessment Scale-Cognitive subscale (adjusted mean difference -1.07, 95% confidence interval (CI) -2.02 to -0.12), but this difference may not be clinically relevant. There was also very low-certainty evidence for greater proportional improvement measured with the Clinician Interview-Based Impression of Change-Plus Caregiver Input (57% with DL-3-n-butylphthalide versus 42% with placebo; P = 0.01), but there was no difference in other measures of cognition (Mini-Mental State Examination and Clinical Dementia Rating) or function. There was no evidence of a difference in adverse events between treatment groups. The SILENCE RCT compared antithrombotic therapy (aspirin) and placebo during four years of treatment in 83 participants with 'silent brain infarcts' who were on no prior antithrombotic therapy. There was very low-certainty evidence for no difference between groups across various measures of cognition and function, rates of stroke or adverse events. The Secondary Prevention of Subcortical Stroke Study (SPS3) compared dual antiplatelet therapy (clopidogrel plus aspirin) to aspirin alone in 3020 participants with recent lacunar stroke. There was low-certainty evidence of no effect on cognitive outcomes as measured by the Cognitive Abilities Screening Instruments (CASI) assessed annually over five years. There was also low-certainty evidence of no difference in the annual incidence of mild cognitive decline between the two treatment groups (9.7% with dual antiplatelet therapy versus 9.9% with aspirin), or the annual stroke recurrence rate (2.5% with dual antiplatelet therapy versus 2.7% with aspirin). Bleeding risk may be higher with dual antiplatelet therapy (hazard ratio (HR) 2.15, 95% CI 1.49 to 3.11; low certainty evidence), but there may be no significant increase in intracerebral bleeding risk (HR 1.52, 95% CI 0.79 to 2.93; low-certainty evidence). None of the included trials assessed the incidence of new dementia.

AUTHORS' CONCLUSIONS

We found no convincing evidence to suggest any clinically relevant cognitive benefit of using antithrombotic therapy in addition to standard treatment in people with cerebral small vessel disease but without dementia, but there may be an increased bleeding risk with this approach. There was marked heterogeneity across the trials and the certainty of the evidence was generally poor.

Blood pressure variability is related to faster cognitive decline in ischemic stroke patients: PICASSO subanalysis

Blood pressure variability (BPV) is associated with higher cardiovascular morbidity risks; however, its association with cognitive decline remains unclear. We investigated whether higher BPV is associated with faster declines in cognitive function in ischemic stroke (IS) patients. Cognitive function was evaluated between April 2010 and August 2015 using the Mini-mental State Examination (MMSE) and Montreal Cognitive Assessment in 1,240 Korean PICASSO participants. Patients for whom baseline and follow-up cognitive test results and at least five valid BP readings were available were included. A restricted maximum likelihood–based Mixed Model for Repeated Measures was used to compare changes in cognitive function over time. Among a total of 746 participants (64.6 ± 10.8 years; 35.9% female). Baseline mean-MMSE score was 24.9 ± 4.7. The median number of BP readings was 11. During a mean follow-up of 2.6 years, mean baseline and last follow-up MMSE scores were 25.4 ± 4.8 vs. 27.8 ± 4.4 (the lowest BPV group) and 23.9 ± 5.2 vs. 23.2 ± 5.9 (the highest BPV group). After adjusting for multiple variables, higher BPV was independently associated with faster cognitive decline over time. However, no significant intergroup difference in cognitive changes associated with mean systolic BP was observed. Further research is needed to elucidate how BPV might affect cognitive function.