Researchers identify crucial risk factors for cognitive decline after stroke

Useless research! Researchers should research how to prevent this cognitive decline.

Researchers identify crucial risk factors for cognitive decline after stroke

In a recent study published in The Lancet Healthy Longevity, researchers performed a meta-analysis to investigate factors that increase post-stroke cognitive impairment (PSCI) and dementia (PSD) risks.

Study: Risk factors for cognitive impairment and dementia after stroke: a systematic review and meta-analysis. Image Credit: SewCreamStudio/Shutterstock.com

The increasing number of stroke survivors worldwide has highlighted the long-term consequences of stroke, particularly cognitive impairments and dementia. This burden on patients, caregivers, and healthcare systems is significant.

Understanding the factors predisposing individuals to stroke-related complications is crucial for patient counseling and prevention trials. However, systematic reviews and meta-analyses are scarce, and there is a lack of pooled estimates for PSCI independent of well-recognized risk factors such as stroke severity and patient age.

About the study

In the present meta-analysis, researchers explored PSCI and PSD risk factors other than stroke severity and age.

The team searched the Cochrane and MEDLINE databases for articles on risk factors for post-stroke cognitive deficits published in English through September 15, 2023. A researcher screened the data, and another researcher resolved discrepancies.

Studies included observational studies, retrospective and prospective cohort-type research, post-hoc analysis from randomized clinical trials, and case-control-type studies of acute stroke patients (hemorrhagic, ischemic, and transient ischemic attack [TIA]), exploring factors contributing to PSD or PSCI risks after 3 months follow-up.

Included records reported summary estimates for binary outcomes (PSD or PSCI) based on predetermined diagnostic criteria, or thresholds in neuropsychological tests, or both; include ≥30 adult patients; and assess risk factors within the first three months after stroke. The researchers also searched the reference lists of the included articles to identify additional records.

They used the Newcastle-Ottawa scale (NOS) to assess the quality of the included studies. They determined the pooled values for relative risks (RRs) by random-effects-type meta-analytical research, including meta-regressions, sensitivity, and subgroup analyses.

Exclusion criteria included animal studies, cross-sectional studies, randomized clinical trials, stroke patients with specific brain regions, subjective studies, cohorts with pre-stroke dementia, cognitive impairment or diseases that may alter cognitive function, and studies without stroke severity and age adjustments. 

The team also excluded studies focusing on cognitive impairment, genetic predispositions, stroke-free controls, continuous cognitive outcomes, trajectories of cognitive performance, domain-specific performance or impairment, and meta-analysis studies without stroke severity and age adjustments.

Results

Out of 13,127 initially identified records, 162 were eligible for the systematic review and 113 (89 studies, including 160,783 stroke patients) for the meta-analysis. The median NOS score for the included studies was 5. 

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Most studies were hospital-based (73 studies, 29,341 patients), while fewer were population- or registry-based. PSCI effect estimates were correlated significantly with those for PSD, with a beta regression coefficient of 0.7 indicating larger effect sizes for PSD than PSCI.

Cognitive impairment at baseline contributed the most to PSCI (relative risk [RR], 2.0) and PSD risks (RR, 3.1). The researchers identified diabetes (RR, 1.3), atrial fibrillation history or presence (RR, 1.3), moderate to severe hyperintensities in white matter (RR, 1.5), and white matter hyperintensity severity (RR, 1.3) as modifiable-type PSCI risk factors, irrespective of stroke severity and age.  

The researchers identified diabetes (RR, 1.4), moderate to severe white matter hyperintensities (RR, 1.6), and white matter hyperintensity severity (RR, 1.6, 1) as modifiable risk factors for PSD. Other risk factors were a lower level of education, prior stroke history, brain atrophy, stroke in the left hemisphere of the brain, the presence of at least three lacunes, and low functional status at baseline. The researchers found considerable heterogeneity and reporting bias in the included studies.

In the subgroup analysis, studies on diabetes and atrial fibrillation showed larger effect sizes for post-dementia stress disorder (PDS) when published before 2009 in a hospital-based setting using a neuropsychological test battery rather than cognitive screening tools.

Meta-regressions showed that a later recruitment date attenuated the association of the National Institute of Health Stroke Scale/Score (NIHSS), educational attainment, and white matter hyperintensity severity with PSD, and a later publication date attenuated the association of NIHSS, educational attainment, and atrial fibrillation with PSD.

Conclusions

Overall, the study findings showed that cognitive impairments in the acute period following stroke are the strongest predictor of post-stroke stroke complications (PSCI) and stroke-related stroke complications (PSD). Diabetes was identified as the main cardiovascular risk factor for cognitive impairments and dementia after stroke, while the role of atrial fibrillation in PSD development is less clear.

Other factors for post-stroke cognitive decline include lower education, prior stroke history, cerebral small vessel disease (cSVD)-associated neuroimaging markers, left hemisphere stroke, urinary incontinence, medial temporal lobe atrophy (MTA), and lower functional status and cognitive performance. Screening for cognitive dysfunction during the acute period after stroke may aid in identifying individuals at increased risks of long-term post-stroke cognitive impairments and dementia.

Journal reference:

• Filler J, Georgakis MK, & Dichgans M (2023). Risk factors for cognitive impairment and dementia after stroke: a systematic review and meta-analysis. Lancet Healthy Longev. doi:10.1016/S2666-7568(23)00217-9. https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(23)00217-9/fulltext

Blood pressure control and risk of post-stroke dementia among the elderly: A population-based screening study

Don't just describe the blood pressure control problem, SOLVE IT!

Blood pressure control and risk of post-stroke dementia among the elderly: A population-based screening study

Hao Wu^1,2†, Zhihong Ren^3†, Jinghuan Gan^4†, Yang Lü⁵, Jianping Niu⁶, Xinling Meng⁷, Pan Cai⁸, Yang Li⁹, Baozhi Gang¹⁰, Yong You¹¹, Yan Lv¹², Shuai Liu², Xiao-Dan Wang² and Yong Ji^1,2*

• ¹Country Clinical College of Neurology, Neurosurgery and Neurorehabilitation, Tianjin Medical University, Tianjin, China
• ²Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Department of Neurology, Tianjin Dementia Institute, Tianjin Huanhu Hospital, Tianjin, China
• ³Department of Neurology, Capital Medical University Electric Teaching Hospital/State Gird Beijing Electric Power Hospital, Beijing, China
• ⁴Department of Cognitive Disorder, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
• ⁵Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
• ⁶Department of Neurology, The Second Affiliated Hospital of Xiamen Medical College, Xiamen, China
• ⁷Department of Neurology, Affiliated Traditional Chinese Medicine Hospital of Xinjiang Medical University, Urumqi, China
• ⁸Dementia Clinic, Affiliated Hospital of Zunyi Medical University, Zunyi, China
• ⁹Department of Neurology, The First Hospital of Shanxi Medical University, Taiyuan, China
• ¹⁰Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
• ¹¹Department of Neurology, Second Affiliated Hospital of Hainan Medical University, Haikou, China
• ¹²Department of Neurology, Hainan General Hospital, Haikou, China

Background: Post-stroke dementia (PSD) has adverse effects on the quality of work and life in elderly stroke survivors. There are inconsistent results on the impacts of blood pressure control on the risk of PSD in people aged 65 years and above.

Objective: This study was performed to explore whether poorly-controlled blood pressure was associated with an increasing risk of PSD.

Methods: The study population was enrolled from cross-sectional research conducted in 106 communities of rural northern China. In Phase I, a total of 7,448 people aged ≥65 years, including 830 with stroke history, completed a questionnaire, a physical examination, and a cognitive assessment. Phase II further confirmed the diagnosis of PSD. Well-controlled blood pressure was defined as an average systolic blood pressure of <140 mmHg and average diastolic blood pressure of <90 mmHg over two readings in person. Failure to meet these criteria was considered as poorly-controlled blood pressure.

Results: The crude prevalence rate of PSD among stroke survivors aged 65 years and over was 17.8% [95% confidence interval (CI) 15.2–20.4%]. Among the 830 stroke survivors, the proportions of PSD gradually increased with age and the crude prevalence rates for PSD were 10.2% (95% CI 5.6–14.9%), 14.8% (95% CI 10.1–19.5%), 18.8% (95% CI 14.1–23.5%), and 27.4% (95% CI 20.8–34.1%) in subjects aged 65–69, 70–74, 75–79 and ≥80 years, respectively. Participants in the poorly-controlled blood pressure group were more likely to suffer from PSD (28.4 vs.15.3%, P < 0.001), be older (75.81 ± 4.97 vs. 74.74 ± 5.83, P < 0.05), and have a worse cognitive level (22.26 ± 7.05 vs. 24.10 ± 6.02, P < 0.05). Compared with well-controlled blood pressure patients, poorly-controlled blood pressure in stroke survivors significantly increased risk of PSD (odds ratio = 2.20, 95% CI 1.45–3.32) after adjusting for age, gender, and education.

Conclusions: The crude prevalence of PSD among stroke survivors aged ≥65 years was 17.8% at community level. In addition to lower education level and older age, poorly-controlled blood pressure was also an independent risk factor for PSD among the elderly, which is amenable to intervention. Therefore, it is essential to control blood pressure to reduce PSD incidence.

Introduction

Stroke and dementia are both common diseases in aging societies (1, 2). People often pay attention to physical disability after stroke (3), while post-stroke dementia (PSD), doubled in the population aged ≥65 years compared to without stroke (4), is often neglected (5). Longitudinal cohorts, based on population- and hospital-based research, showed that PSD incidence increased 1.7–3.0% every year (6). With the aging of society and improved survival from stroke, the numbers of patients with PSD will increase. Although many studies have reported the prevalence of PSD, the results vary from 7% in general population to over 50.0% among hospital patients (6, 7). The sample size, study design (hospital-based or population-based studies), as well as the cognitive assessment time (after stroke 6 months or 1 year) contributed to the inconsistence and great variation. However, there have been a few epidemiological studies on PSD among the elderly at community level in China.

The risk of PSD overlaps with the risk of stroke and dementia. Current studies (8–11) revealed significant predictors of PSD, including age >65 years, low education level, previous cognitive decline, vascular risk factors, stroke features, and neuroimaging factors. Although there have been many studies with a high level of evidence, the influence of some factors on PSD occurrence remains unclear, such as high blood pressure.

High blood pressure, which affects more than 75% of people over the age of 65 years, is the leading risk factor for stroke and many other vascular diseases (12). Thus, high blood pressure likely plays an important role in PSD development, although this association remains unclear (10, 13). In several randomized clinical trials concerning the effects of blood pressure reductions on cognitive outcomes, results have generally been inconclusive (14, 15). Some research suggests that the relationship between blood pressure and dementia may be age dependent (16), with high blood pressure at midlife (age 40–64 years) being associated with an increased risk of late-life dementia (17, 18). However, there is no consensus on the association between blood pressure and dementia in those aged 65 years and above. These varied results may be attributed to differences in subtype and cause of dementia. PSD is mainly the result of ischemia of the brain parenchyma caused by atherosclerotic disease (19). Therefore, our study focuses on the relationship between blood pressure control and PSD among the elderly population, so as to explore the potential modifiable risk factors for PSD.

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