Understanding and preventing the development of post-stroke dementia

Activation changes in patients with post-stroke cognitive impairment receiving intermittent theta burst stimulation: A functional near-infrared spectroscopy study

BACKGROUND

Intermittent theta burst stimulation (iTBS) has demonstrated efficacy in patients with cognitive impairment. However, activation patterns and mechanisms of iTBS for post-stroke cognitive impairment (PSCI) remain insufficiently understood.

OBJECTIVE

To investigate the activation patterns and potential benefits of using iTBS in patients with PSCI.

METHODS

A total of forty-four patients with PSCI were enrolled and divided into an iTBS group (iTBS and cognitive training) or a control group (cognitive training alone). Outcomes were assessed based on the activation in functional near-infrared spectroscopy (fNIRS), as well as Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) and the modified Barthel Index (MBI).

RESULTS

Thirty-eight patients completed the interventions and assessments. Increased cortical activation was observed in the iTBS group after the interventions, including the right superior temporal gyrus (STG), left frontopolar cortex (FPC) and left orbitofrontal cortex (OFC). Both groups showed significant improvements in LOTCA and MBI after the interventions (p < 0.05). Furthermore, the iTBS group augmented superior improvement in the total score of MBI and LOTCA compared to the control group, especially in visuomotor organization and thinking operations (p < 0.05).

CONCLUSION

iTBS altered activation patterns and improved cognitive function in patients with PSCI. The activation induced by iTBS may contribute to the improvement of cognitive function.

The HALP (hemoglobin, albumin, lymphocyte, and platelet) score is associated with early-onset post-stroke cognitive impairment

BACKGROUND

The HALP score (hemoglobin, albumin, lymphocyte, and platelet) is a novel indicator that measures systemic inflammation and nutritional status. The goal of this study was to look into the relationship between the HALP score and post-stroke cognitive impairment (PSCI) in people who had an acute ischemic stroke (AIS).

METHODS

A total of 592 individuals with ischemic stroke were included in the research, and the PSCI (n = 382) and non-PSCI (n = 210) groups were determined using the Mini-Mental State Examination scale 2 weeks following the stroke. HALP score was computed by the formula: hemoglobin (g/L) × albumin (g/L) × lymphocytes (/L) / platelets (/L), and was split into three layers according to the tertiles. The connection between the HALP and cognitive results was investigated by binary logistic regression.

RESULTS

The PSCI group's HALP score was much lower than the non-PSCI group's (p < 0.001). The HALP score was divided into three layers: T1 ≤ 34.0, T2 34.1-49.4, and T3 ≥ 49.5, respectively. In the binary regression analysis, taking the T3 layer as the reference, the T1 layer showed the highest risk of PSCI after adjusting for confounding factors (odds ratio (OR) = 1.965, 95% confidence interval (CI) = 1.237-3.122, p = 0.004), while there was no increased risk of PSCI in the T2 layer (OR = 1.538, 95%CI = 0.983-2.404, p = 0.059).

CONCLUSION

Low HALP score at admission was found to be correlated with early-onset PSCI and may help clinicians in the early identification of high-risk patients.

Clinical Risk Score for Predicting Vascular Dementia after Ischemic Stroke in Thailand

Background. Poststroke dementia is an important consequence of stroke and warrants early prevention, detection, and management. The objective of the study was to develop a simple clinical risk score for predicting risk of vascular dementia in patients with ischemic stroke. Methods. The design was a prospective cohort study with 177 ischemic stroke survivors. A standard stroke evaluation was performed at admission, and dementia evaluation was conducted at six months after stroke. The significant predictors were used to develop a risk score using a multivariable logistic regression model. Results. Six months after stroke, 27.1% of the patients were diagnosed with vascular dementia. Five predictors were used in the risk score: age, education, history of stroke, white matter hyperintensities, and stroke subtype. The risk score had an area under receiver operating characteristic curve (AuROC) of 0.76, 72.9% sensitivity, and 79.1% specificity in predicting risk of vascular dementia. The predicted probability of vascular dementia for each risk score point was also reported. Conclusion. The clinical risk score had an acceptable accuracy in predicting vascular dementia in ischemic stroke survivors. It can be used for identifying those who are at a high risk of developing vascular dementia.

Current view on post-stroke dementia

Dementia is one of the leading complications after stroke affecting about one third of survivors. Prevalence of post-stroke dementia (PSD) differs between studies due to variability in methodology, characteristics of included patients, type of stroke, diagnostic tools used to identify patients with dementia, or time when the assessment was performed. Patients diagnosed with PSD are at higher risk of mortality, disability, and institutionalization. Aetiology of PSD may include mixed overlapping processes such as vascular brain pathology or Alzheimer's disease. Several risk factors have been found to increase PSD incidence, involving demographics, vascular factors, stroke characteristics, abnormalities on neuroimaging, and stroke complications. However, the influence of some other factors still remains unclear. PSD may coexist with other neuropsychiatric disorders and its association with post-stroke depression seems to be the most significant. There is a strong need for further research on possible genetic, biological, and inflammatory biomarkers. Also, there are no unambiguously efficacious methods of management. Continuing to address these issues will help to find more effective interventions directly targeting prevention and treatment of PSD in the future.

Cerebrolysin for vascular dementia

BACKGROUND

Although vascular dementia is the second most common cause of dementia globally, evidence-based treatments are still lacking. Cerebrolysin is a porcine brain-derived preparation that is said to have neurotrophic and neuroprotective activity. In many parts of the world Cerebrolysin, given as a series of daily intravenous infusions, is used as a potential intervention for vascular dementia. A previous Cochrane Review on Cerebrolysin in vascular dementia yielded inconsistent results. We wished to update the review to add new studies from the international literature and employ contemporary methods for appraising the strength of the evidence. This is the first update of a review first published in 2013.

OBJECTIVES

Primary: to assess the effect of Cerebrolysin on cognitive function, global function, and all-cause mortality in people living with vascular dementia. Secondary: to assess the adverse effects of Cerebrolysin and to assess the effect of Cerebrolysin on quality of life and caregiver burden.

SEARCH METHODS

We searched ALOIS, MEDLINE, Embase, PsycINFO, CINAHL, ISI Web of Knowledge, LILACS, the Cochrane Library, ClinicalTrials.gov, and the WHO ICTRP on 16 June 2017, 9 May 2018, and 9 May 2019. We expanded the search by adding four Chinese databases, searched from 1 January 2012 to 19 May 2019. We checked bibliographies of relevant papers identified and contacted pharmaceutical companies, trial authors, and experts in the field to identify any additional published or unpublished data.

SELECTION CRITERIA

We included all randomised controlled trials of Cerebrolysin used in people living with vascular dementia. We applied no language restriction.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and evaluated their methodological quality. Data were extracted and analysed using mean differences (MDs) or standardised mean differences (SMDs) with 95% confidence intervals (95% CI) for continuous outcomes. We reported dichotomous outcomes as risk ratio (RR) with 95% CI. We assessed the strength of the available evidence using the GRADE approach.

MAIN RESULTS

We identified six randomised controlled trials with a total of 597 participants that were eligible for inclusion in the 2013 review. No new studies were eligible for inclusion in this update. Participants in the included studies, where dementia severity was reported, had mild to moderate severity of vascular dementia (four trials). The included studies tested varying doses and duration of Cerebrolysin treatment. Follow-up ranged from 15 days to three years. Five of included studies were conducted in China (three studies), Russia (one study), and Romania (one study), while relevant information of other study was unclear. Where details of funding were available, all studies were supported by the pharmaceutical industry (three studies). Cognitive function was measured using the Mini-Mental State Examination (MMSE) or Alzheimer's Disease Assessment Scale Cognitive Subpart, extended version (ADAS-cog+). Combining the MMSE and ADAS-cog+ data (three studies, 420 people), there was a beneficial effect of Cerebrolysin (SMD 0.36, 95% CI 0.13 to 0.58; very low-quality evidence). Global function was measured by Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC+) or Investigator's Clinical Global Impression (CGI). We assessed response rates on these measures (the proportion of participants with a CIBIC+ score of < 3; or at least moderate improvement of the CGI rating at the last visit). There was a beneficial effect of Cerebrolysin (two studies, 379 participants, RR 2.69, 95% CI 1.82 to 3.98; very low-quality evidence). Only one trial described mortality and reported no deaths. Four studies reported adverse events; data from two studies (379 people) were in a format that permitted meta-analysis, and there was no difference in rates of adverse effects (RR 0.91, 95% CI 0.29 to 2.85; very low-quality evidence). No studies reported on quality of life or caregiver burden.

AUTHORS' CONCLUSIONS

Courses of intravenous Cerebrolysin improved cognition and general function in people living with vascular dementia, with no suggestion of adverse effects. However, these data are not definitive. Our analyses were limited by heterogeneity, and the included papers had high risk of bias. If there are benefits of Cerebrolysin, the effects may be too small to be clinically meaningful. There have been no new studies of Cerebrolysin in vascular dementia since the last Cochrane Review. Cerebrolysin continues to be used and promoted as a treatment for vascular dementia, but the supporting evidence base is weak. Adequately powered, methodologically robust trials are needed to properly assess the effects of Cerebrolysin in vascular dementia.

Linking Atrial Fibrillation with Alzheimer's Disease: Epidemiological, Pathological, and Mechanistic Evidence

Many studies have shown a relationship between atrial fibrillation (AF) and vascular dementia. AF is a major risk factor for stroke, and stroke is the greatest risk factor for vascular dementia. However, the relationship between Alzheimer's disease (AD), the leading cause of dementia, and AF remains unclear. At least four epidemiological studies have reported AF significantly raises the risk of AD 1.5- to 2.5-fold. Chronic cerebral hypoperfusion, resulting from persistent AF, could explain the link as hypoperfusion may mechanistically exacerbate amyloid-β (Aβ) neuropathology, such as senile plaques and amyloid angiopathy, by upregulating Aβ-producing enzymes and lowering Aβ clearance efficiency. In addition, hypoperfusion may exacerbate tau pathology directly through upregulation of tau-phosphorylating enzymes and indirectly via the amyloid cascade. However, most neuropathological studies do not support the direct link between AD pathology and AF but rather suggests vascular neuropathology is related to, or coexistent with, AF and lowers the threshold for clinically-evident AD. Vascular neuropathology may thus mediate the link between AD and AF. From a treatment perspective, an observational study has shown that catheter ablation is associated with less incidence of AD in AF patients, suggesting rhythm-control suppresses hypoperfusion-induced AD neuropathology. In addition, rate-control may lower the rate of cognitive decline in cognitively impaired elderly subjects with AF. Further studies are warranted to clarify the mechanisms underlying the linkage between AF and AD. However, anticoagulation and rhythm-/rate-control against AF may hold promise even for AD patients.

Hypertension, diabetes and obesity are associated with lower cognitive performance in community-dwelling elderly: Data from the FIBRA study

Background

Systemic hypertension (SH), diabetes mellitus (DM) and abdominal obesity may negatively impact cognitive performance.

Objective

To evaluate the association between SH, DM and abdominal obesity and cognitive performance among cognitively unimpaired elderly.

Methods

A cross-sectional study of individuals aged 65+ from seven Brazilian cities was conducted. SH and DM diagnoses were self-reported and abdominal circumference was objectively measured. Individuals who scored below the education-adjusted cutoff scores on the Mini-Mental State Examination (MMSE) were excluded.

Results

Among 2,593 elderly, 321 (12.38%) had SH, DM and abdominal obesity concomitantly (Group I) and 421 (16.23%) had none of the three diseases (Group II). Group I had a higher proportion of individuals that were women, aged 70-74 years, illiterate and with lower income. Group I had a higher number of participants with low cognitive performance (28.04% vs. 17.58% in Group II). Variables associated with poor cognitive performance were: female gender (OR: 2.43, p < 0.001); and lower education (OR: 0.410, p < 0.001). The presence of the three diseases and age were not significant in the education-adjusted model.

Conclusion

There was an association between cognition and the presence of SH, DM and obesity. However, education seems to be decisive in determining cognitive performance in the presence of these three conditions.

Influence of Low-Dose Aspirin on Cerebral Amyloid Angiopathy in Mice

Accumulation of amyloid-β peptide (Aβ) in the brain is one of the most important features of Alzheimer's dementia (AD). Cerebral amyloid angiopathy (CAA) is characterized by Aβ accumulation in the walls of cerebral arteries and capillaries, and is present in over 90% of patients with AD. Several novel agents for AD/CAA developed around the amyloid hypothesis have shown positive signs in animal studies but have failed in clinical trials due to adverse events and/or lack of efficiency. As CAA is presumably caused by a failure in Aβ clearance, drugs that promote Aβ clearance may hold promise in the treatment of CAA and possibly AD. With this in mind, cilostazol, an anti-platelet drug with vasodilating action, has been found to promote Aβ clearance along perivascular drainage pathway, reduce Aβ accumulation in the brain, and restore memory impairment in Tg-SwDI mice, an animal model of CAA. We therefore tested whether the most common anti-platelet agent, aspirin, also reduced Aβ and rescued cognitive impairment in Tg-SwDI mice, and also whether aspirin affected hemorrhagic complications that can occur in Tg-SwDI mice. Mice aged 4 months were assigned into vehicle-treated and low-dose aspirin-treated groups. Low-dose aspirin for 8 months did not increase hemorrhagic lesions, nor increase resting cerebral blood flow or cerebral vascular reserve in response to hypercapnia or acetylcholine. Subsequently, aspirin did not restore cognitive dysfunction. These results suggest that low-dose aspirin does not have a direct influence on cerebrovascular Aβ metabolism nor aggravate hemorrhagic complications in CAA.

Effect of Selective 5-HT6R Agonist on Expression of 5-HT Receptor and Neurotransmitter in Vascular Dementia Rats

Background

5-HT6 receptor (5-HT6R) has pluripotent roles regulating secretion of neurotransmitters. However, whether 5-HT6R is involved in the development of vascular dementia (VD) remains unclear. To evaluate the role and mechanism of 5-HT6R in VD, this study established a rat VD model to evaluate the effect of selective 5-HT6R agonist on the expression of 5-HT6R mRNA and neurotransmitter.

Material/Methods

Eighty healthy male SD rats (7 weeks old) were randomly assigned to sham, model, 5-HT6R agonist, and placebo groups (N=20 each). A rat VD model was generated by permeant bilateral ligation of the common carotid artery. 5-HT6R agonist, placebo, or saline were given intraperitoneally for 4 weeks. The Morris water maze was utilized to test learning and memory function. Brains were extracted to separate the cortex and hippocampal tissues, in which glutamate and γ-aminobutyric acid (GABA) levels were analyzed. mRNA and protein levels of 5-HT6R were determined by RT-PCR and immunohistochemistry (IHC), respectively.

Results

Model rats had longer escape latency and fewer crossing platform times. Contents of DA, Glu, GABA, and Ach were lowered in cortical and hippocampal tissues, and 5-HT6R expression was suppressed (p<0.05). The application of 5-HT6R agonist shortened escape latency and increased the number of passing through the platform. It also improved hippocampal CA1 neuronal damage and elevated DA, Glu, GABA, and Ach contents and expression of 5-HT6R. Expression of 5-HT6R was not different from the placebo group.

Conclusions

Selective 5-HT6R agonist can alleviate learning deficit of VD rats, possibly via improving neurotransmitter levels in brain regions.

Neuroprotection in ischemic stroke: what does the future hold?

Neurodegenerative and vascular disease processes are commonly found concurrently in the brains of elderly patients, highlighting the difficulty in determining which processes may be responsible for cognitive impairment. Therapeutically, it may be more sensible to assume that most patients have mixed dementia. Therefore, therapies with multimodal modes of action would be expected to confer neuronal protection. Ischemic stroke is also associated with a complex pathophysiology and a high incidence of post-stroke cognitive impairment, but evidence for the efficacy of neuroprotective treatments in humans is contradictory (mainly due to a failed translation from bench to bedside). Nevertheless, emerging drug therapies continue to undergo testing in prospective, randomized, controlled studies. Natural biologicals, such as Actovegin, or smaller biological molecules with multifaceted effects in the restorative phase of ischemia are likely candidates for efficacy testing. In addition, a number of non-pharmacological interventions, especially lifestyle interventions, are also the subject of current research and would eventually be expected to supplement the treatment and prevention of ischemic stroke.

Mild cognitive impairment: vascular risk factors in community elderly in four cities of Hebei Province, China

Background

Evidence has demonstrated that vascular risk factors (VRFs) contribute to mild cognitive impairment (MCI) in the elderly population. Because of the race and different diagnosis standard, there is still no definitive conclusions.

Objective

To estimate the VRFs and potential protective factors for MCI in elderly population living in the community in North China.

Methods

A total of 3136 participants entered the study. They were screened for hypertension, coronary heart disease (CHD), and cerebrovascular disease (CVD). Cognitive function was assessed with Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). The diagnosis of MCI was made according to Petersen’s criteria. We investigated the relationship between vascular risk factors, potential protective factors and MCI.

Results

A total of 2511 (80%) participant belonged to normal group and 625 (20%) participants showed MCI. Multiple logistic regression analysis demonstrated that stroke and diabetes, but not hypertension or CHD was associated with MCI. Besides, exercise habit could lower the risk of MCI.

Conclusions

Vascular Risk Factors, including stroke and diabetes, rather than hypertension and CHD are independent risk factors of MCI. Involvement in physical activities seems to reduce the risk of MCI.

A novel mouse model of subcortical infarcts with dementia

Subcortical white matter (WM) is a frequent target of ischemic injury and extensive WM lesions are important substrates of vascular cognitive impairment (VCI) in humans. However, ischemic stroke rodent models have been shown to mainly induce cerebral infarcts in the gray matter, while cerebral hypoperfusion models show only WM rarefaction without infarcts. The lack of animal models consistently replicating WM infarct damage may partially explain why many neuroprotective drugs for ischemic stroke or VCI have failed clinically, despite earlier success in preclinical experiments. Here, we report a novel animal model of WM infarct damage with cognitive impairment can be generated by surgical implantation of different devices to the right and left common carotid artery (CCA) in C57BL/6J mice. Implantation of an ameroid constrictor to the right CCA resulted in gradual occlusion of the vessel over 28 d, whereas placement of a microcoil to the left CCA induced ∼50% arterial stenosis. Arterial spin labeling showed a gradual reduction of cerebral blood flow over 28 d post operation. Such reductions were more marked in the right, compared with the left, hemisphere and in subcortical, rather than the cortical, areas. Histopathological analysis showed multiple infarct damage in right subcortical regions, including the corpus callosum, internal capsule, hippocampal fimbria, and caudoputamen, in 81% of mice. Mice displaying such damage performed significantly poorer in locomotor and cognitive tests. The current mouse model replicates the phenotypes of human subcortical VCI, including multiple WM infarcts with motor and cognitive impairment.

Effect of stent-assisted angioplasty on cognitive status and serum levels of amyloid beta in patients with intracranial and/or extracranial artery stenosis

AIM

The study reported here aimed to examine how stent-assisted angioplasty affects cognitive status and serum levels of amyloid betas (Aβs) 1-40 and 1-42 in patients with cerebral arterial stenosis.

METHODS

Patients with cerebral arterial stenosis were given stent-assisted angioplasty plus conventional treatment (stent-assisted angioplasty group) or conventional treatment alone (control group). Cognitive status and Aβ1-40 and Aβ1-42 serum levels were determined before treatment and at 4 and 8 weeks after treatment.

RESULTS

At 4 weeks after treatment, cognitive status in patients with stent-assisted angioplasty had clearly improved. Aβ1-42 serum levels changed insignificantly in all patients. However, Aβ1-40 serum levels and Aβ1-40/Aβ1-42 ratio decreased further in patients with stent-assisted angioplasty than in patients who received conventional treatment (controls). Eight weeks after treatment, cognitive status in patients who had undergone stent-assisted angioplasty were continuing to improve, Aβ1-42 serum levels had begun to increase dramatically, and Aβ1-40 serum levels and Aβ1-40/Aβ1-42 ratio had declined further.

CONCLUSION

Stent-assisted angioplasty could improve cognitive status and decrease Aβ1-40 serum levels and Aβ1-40/Aβ1-42 ratio.