Cognitive and functional decline in African Americans with VaD, AD, and stroke without dementia

Development and validation of an interpretable machine learning model-Predicting mild cognitive impairment in a high-risk stroke population

Background

Mild cognitive impairment (MCI) is considered a preclinical stage of Alzheimer's disease (AD). People with MCI have a higher risk of developing dementia than healthy people. As one of the risk factors for MCI, stroke has been actively treated and intervened. Therefore, selecting the high-risk population of stroke as the research object and discovering the risk factors of MCI as early as possible can prevent the occurrence of MCI more effectively.

Methods

The Boruta algorithm was used to screen variables, and eight machine learning models were established and evaluated. The best performing models were used to assess variable importance and build an online risk calculator. Shapley additive explanation is used to explain the model.

Results

A total of 199 patients were included in the study, 99 of whom were male. Transient ischemic attack (TIA), homocysteine, education, hematocrit (HCT), diabetes, hemoglobin, red blood cells (RBC), hypertension, prothrombin time (PT) were selected by Boruta algorithm. Logistic regression (AUC = 0.8595) was the best model for predicting MCI in high-risk groups of stroke, followed by elastic network (ENET) (AUC = 0.8312), multilayer perceptron (MLP) (AUC = 0.7908), extreme gradient boosting (XGBoost) (AUC = 0.7691), and support vector machine (SVM) (AUC = 0.7527), random forest (RF) (AUC = 0.7451), K-nearest neighbors (KNN) (AUC = 0.7380), decision tree (DT) (AUC = 0.6972). The importance of variables suggests that TIA, diabetes, education, and hypertension are the top four variables of importance.

Conclusion

Transient ischemic attack (TIA), diabetes, education, and hypertension are the most important risk factors for MCI in high-risk groups of stroke, and early intervention should be performed to reduce the occurrence of MCI.

Community Engagement: Lessons Learned From the AAASPS and SDBA

Community engagement is a means to help overcome challenges to the delivery of health care and preventative services. On the occasion of the 2021 International Stroke Conference Edgar J. Kenton III Lecture, I review community engagement strategies utilized in the AAASPS trial (African-American Antiplatelet Stroke Prevention Study) and SDBA (Studies of Dementia in the Black Aged) observational studies that I directed. The main community engagement strategies included use of home visits (bringing the study to the community), engagement of churches, community advisors, community physicians, other healthcare providers, major Black community organizations, and utilization of diversity training. Community engagement strategies were a major component of AAASPS and SDBA that helped to ensure successful recruitment and retention of an underrepresented community in clinical trial and observational studies. Lessons learned from these studies largely carried out in the 1980s and 1990s helped to dispel myths that Blacks could not be recruited into large-scale clinical trials, emphasized the importance of studying underrepresented groups with adequate statistical power to test primary study hypotheses, and provided foundational recruitment and retention methods for future consideration.

Study protocol on Alzheimer's disease and related disorders: focus on clinical and imaging predictive markers in co-existing lesions

BACKGROUND

One of the crucial challenges for the future of therapeutic approaches to Alzheimer's disease (AD) is to target the main pathological processes responsible for disability and dependency. However, a progressive cognitive impairment occurring after the age of 70, the main population affected by dementia, is often related to mixed lesions of neurodegenerative and vascular origins. Whereas young patients are mostly affected by pure lesions, ageing favours the occurrence of co-lesions of AD, cerebrovascular disease (CVD) and Lewy body dementia (LBD). Most of clinical studies report on functional and clinical disabilities in patients with presumed pure pathologies. But, the weight of co-morbid processes involved in the transition from an independent functional status to disability in the elderly with co-lesions still remains to be elucidated. Neuropathological examination often performed at late stages cannot answer this question at mild or moderate stages of cognitive disorders. Brain MRI, Single Photon Emission Computed Tomography (SPECT) with DaTscan®, amyloid Positron Emission Tomography (PET) and CerebroSpinal Fluid (CSF) AD biomarkers routinely help in performing the diagnosis of underlying lesions. The combination of these measures seems to be of incremental value for the diagnosis of mixed profiles of AD, CVD and LBD. The aim is to determine the clinical, neuropsychological, neuroradiological and biological features the most predictive of cognitive, behavioral and functional impairment at 2 years in patients with co-existing lesions.

METHODS

A multicentre and prospective cohort study with clinical, neuro-imaging and biological markers assessment will recruit 214 patients over 70 years old with a cognitive disorder of AD, cerebrovascular and Lewy body type or with coexisting lesions of two or three of these pathologies and fulfilling the diagnostic criteria for dementia at a mild to moderate stage. Patients will be followed every 6 months (clinical, neuropsychological and imaging examination and collection of cognitive, behavioural and functional impairment) for 24 months.

DISCUSSION

This study aims at identifying the best combination of markers (clinical, neuropsychological, MRI, SPECT-DaTscan®, PET and CSF) to predict disability progression in elderly patients presenting coexisting patterns.

TRIAL REGISTRATION

NCT02052947 .

Pharmacotherapy for Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) is the second most common type of dementia after Alzheimer's disease (AD). Stroke and cardiovascular risk factors have been linked to both AD and VCI and potentially can affect cognitive function in mid and later life. Various pharmacological agents, including donepezil, galantamine, and memantine, approved for the treatment of AD have shown modest cognitive benefits in patients with vascular dementia (VaD). However, their functional and global benefits have been inconsistent. Donepezil has shown some cognitive benefit in patients with VaD only, and galantamine has shown some benefit in mixed dementia (AD/VaD). The benefits of other drugs such as rivastigmine, memantine, nimodipine, and piracetam are not clear. Some other supplements and herbal therapies, such as citicoline, actovegin, huperzine A, and vinpocetine, have also been studied in patients with VaD, but their beneficial effects are not well established. Non-drug therapies and lifestyle modifications such as diet, exercise, and vascular risk factor control are important in the management of VCI and should not be ignored. However, there is a need for more robust clinical trials focusing on executive function and other cognitive measures and incorporation of newer imaging modalities to provide additional evidence about the utility of these strategies in patients with VCI.

Slow gait speed is associated with executive function decline in older people with mild to moderate dementia: A one year longitudinal study

OBJECTIVES

This study aimed to document change in neuropsychological, physical and functional performance over one year and to investigate the relationship between baseline gait speed and cognitive decline in this period in older people with dementia.

METHODS

One hundred and seventy-seven older people with dementia (Mini-Mental State Examination 11-23; Addenbrooke's Cognitive Examination-Revised <83) residing in the community or low level care facility completed baseline neuropsychological, physical and functional assessments. Of these, 134 participants agreed to reassessment of the above measures one year later.

RESULTS

Overall, many neuropsychological, physical and functional performance measures declined significantly over the one year study period. Baseline gait speed was significantly associated with decline in verbal fluency (B(109)=2.893, p=0.046), specifically phonemic/letter fluency (B(109)=2.812, p=0.004) while controlling for age, education, dementia drug use and baseline cognitive performance. There was also a trend for an association between baseline gait speed and decline in clock drawing performance (B(107)=0.601, p=0.071).

CONCLUSIONS

Older people with mild to moderate dementia demonstrate significant decline in neuropsychological, physical and functional performance over one year. Baseline gait speed is associated with decline in executive function over one year, suggesting shared pathways/pathology between gait and cognition.

Progression of cognitive impairment in stroke/TIA patients over 3 years

OBJECTIVES

To examine how cognitive deficits progress in the years following a stroke or transient ischaemic attack (TIA).

METHODS

A follow-up study, with neuropsychological and MRI assessments undertaken 3 years after baseline assessments made 3-6 months poststroke in 183 stroke/TIA patients and 97 healthy controls participating in the Sydney Stroke Study. Additional measures included cardiovascular risk factors and apolipoprotein E (APOE) genotype.

RESULTS

Stroke/TIA patients had poorer cognitive function and more vascular risk factors than controls at baseline, but did not show greater decline in cognitive function over 3 years except for verbal memory. Patients with a subsequent stroke/TIA showed greater decline in global cognitive function and a number of domains. Rates of incident dementia were 5.9% per year in patients and 0.4% in controls. Both groups showed increased atrophy of the hippocampus, amygdala and whole brain, and an increase in white matter hyperintensities over 3 years; whole brain atrophy was greater in patients. Cognitive decline was greater in women and in those with smaller hippocampi at baseline. For patients without a subsequent stroke/TIA, those with smaller hippocampi or the APOE ε4 allele had greater global cognitive and verbal memory decline.

CONCLUSIONS

In poststroke patients, cognitive decline was not greater than in comparison subjects, except for verbal memory, unless they had another stroke/TIA. However, dementia incidence was higher in patients, as might be expected from their poorer baseline cognitive functioning. Smaller hippocampi were associated with an increased risk of decline in memory, and APOE ε4 was a risk factor in those without a subsequent stroke/TIA.

Effects of long-term blood pressure lowering and dual antiplatelet treatment on cognitive function in patients with recent lacunar stroke: a secondary analysis from the SPS3 randomised trial

BACKGROUND

The primary outcome results for the SPS3 trial suggested that a lower systolic target blood pressure (<130 mm Hg) might be beneficial for reducing the risk of recurrent stroke compared with a higher target (130-149 mm Hg), but that the addition of clopidogrel to aspirin was not beneficial compared with aspirin plus placebo. In this prespecified secondary outcome analysis of the SPS3 trial, we aimed to assess whether blood pressure reduction and dual antiplatelet treatment affect changes in cognitive function over time in patients with cerebral small vessel disease.

METHODS

In the SPS3 trial, patients with recent (within 6 months) symptomatic lacunar infarcts from 81 centres in North America, Latin America, and Spain were randomly assigned, in a two-by-two factorial design, to target levels of systolic blood pressure (1:1; 130-149 mm Hg vs <130 mm Hg; open-label) and to a once-daily antiplatelet treatment (1:1; aspirin 325 mg plus clopidogrel 75 mg vs aspirin 325 mg plus placebo; double-blind). For this analysis, the main cognitive outcome was change in Cognitive Abilities Screening Instrument (CASI) during follow-up. Patients were tested annually for up to 5 years, during which time the mean difference in systolic blood pressure was 11 mm Hg (SD 16) between the two targets (138 mm Hg vs 127 mm Hg at 1 year). We used linear mixed models to compare changes in CASI Z scores over time. The SPS3 trial is registered with ClinicalTrials.gov, number NCT00059306.

FINDINGS

The study took place between March 23, 2003, and April 30, 2012. 2916 of 3020 SPS3 participants (mean age 63 years [SD 11]) with CASI scores at study entry were included in the analysis, with a median follow-up of 3·0 years (IQR 1·0-4·9). Mean changes in CASI Z scores from study entry to assessment at years 1 (n=2472), 2 (n=1968), 3 (n=1521), 4 (n=1135), and 5 (n=803) were 0·12 (SD 0·83), 0·15 (0·84), 0·16 (0·95), 0·19 (0·99), and 0·14 (1·09), respectively. Changes in CASI Z scores over time did not differ between assigned antiplatelet groups (p=0·858) or between assigned blood pressure target groups (p=0·520). There was no interaction between assigned antiplatelet groups and assigned blood pressure target groups and change over time (p=0·196).

INTERPRETATION

Cognitive function is not affected by short-term dual antiplatelet treatment or blood pressure reduction in fairly young patients with recent lacunar stroke. Future studies of cognitive function after stroke should be of longer duration or focus on patients with higher rates of cognitive decline.

FUNDING

US National Institute of Neurological Disorders and Stroke.

Impairment of functional integration of the default mode network correlates with cognitive outcome at three months after stroke

Resting‐state studies conducted with stroke patients are scarce. The study of brain activity and connectivity at rest provides a unique opportunity for the investigation of brain rewiring after stroke and plasticity changes. This study sought to identify dynamic changes in the functional organization of the default mode network (DMN) of stroke patients at three months after stroke. Eleven patients (eight male and three female; age range: 48–72) with right cortical and subcortical ischemic infarctions and 17 controls (eleven males and six females; age range: 57–69) were assessed by neurological and neuropsychological examinations and scanned with resting‐state functional magnetic ressonance imaging. First, we explored group differences in functional activity within the DMN by means of probabilistic independent component analysis followed by a dual regression approach. Second, we estimated functional connectivity between 11 DMN nodes both locally by means of seed‐based connectivity analysis, as well as globally by means of graph‐computation analysis. We found that patients had greater DMN activity in the left precuneus and the left anterior cingulate gyrus when compared with healthy controls (P < 0.05 family‐wise error corrected). Seed‐based connectivity analysis showed that stroke patients had significant impairment (P = 0.014; threshold = 2.00) in the connectivity between the following five DMN nodes: left superior frontal gyrus (lSFG) and posterior cingulate cortex (t = 2.01); left parahippocampal gyrus and right superior frontal gyrus (t = 2.11); left parahippocampal gyrus and lSFG (t = 2.39); right parietal and lSFG (t = 2.29). Finally, mean path length obtained from graph‐computation analysis showed positive correlations with semantic fluency test (r_s = 0.454; P = 0.023), phonetic fluency test (r_s = 0.523; P = 0.007) and the mini mental state examination (r_s = 0.528; P = 0.007). In conclusion, the ability to regulate activity of the DMN appears to be a central part of normal brain function in stroke patients. Our study expands the understanding of the changes occurring in the brain after stroke providing a new avenue for investigating lesion‐induced network plasticity. Hum Brain Mapp 36:577–590, 2015. © 2014 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Assessment and prediction of functional impairment in vascular dementia

Vascular dementia is associated with cognitive, physical and functional impairments that often lead to disability among the elderly. Declines in activities of daily living significantly contribute to the disability reported among patients with vascular dementia and compromise quality of life for both patients and their families. Assessment of activities of daily living is an important component of the diagnosis, tracking and management of vascular dementia patients. Furthermore, an understanding of the determinants of activities of daily living dysfunction may provide an earlier identification of individuals at risk for functional disability and allow opportunities for improved patient care. In this review, methods for assessing and tracking activities of daily living are discussed and the literature on the correlates of functional impairment in vascular dementia is summarized. Also, the potential use of executive dysfunction as a marker for instrumental activities of daily living impairment is discussed and recommendations for clinical practice and future research are provided.

Do Alzheimer's disease (AD) and subcortical ischemic vascular dementia (SIVD) progress differently?

Our study aimed to compare cognitive status and declines in AD with/without small vessel disease (SVD) and SIVD at baseline and 1-year follow-up. Patients with Alzheimer's disease without small vessel disease (AD(-)SVD) (n=148), Alzheimer's disease with small vessel disease (AD(+)SVD) (n=94) and SIVD (n=60) were recruited from database of multiple centers in Korea. Basic demographics and detailed neuropsychological results were compared. AD, regardless of SVD, showed worse memory and better executive function than SIVD at baseline. Mini-Mental State Examination scores and visual memory function declined more in AD than those in SIVD whereas Barthel Activities of Daily Living (B-ADL) scores declined more in SIVD. AD showed different patterns of cognitive impairment compared with SIVD. After 1 year, AD showed more rapid cognitive decline in some domains. Further investigations with longer follow-up duration may be needed to confirm the cumulative effects of SVD in AD and different patterns of decline between AD and SIVD.

Differences in rate of functional decline across three dementia types

BACKGROUND

The purpose of this study was to estimate differences in rates of functional decline in Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and vascular dementia (VaD) and whether differences vary by age or sex.

METHODS

Data came from 32 U.S. Alzheimer's Disease Centers. The cohort of participants (n = 5848) were ≥60 years of age and had clinical dementia with a primary etiologic diagnosis of probable AD, DLB, or probable VaD; a Clinical Dementia Rating-Sum of Boxes score <16; and a duration of symptoms ≤10 years. Dementia diagnoses were assigned using standard criteria. Annual mean rate of change of the Functional Activities Questionnaire (FAQ) score was modeled using multiple linear regression with generalized estimating equations adjusted for demographics, comorbidities, years since onset, and cognitive status (mean follow-up = 2.0 years).

RESULTS

FAQ declined more slowly over time in those with VaD compared with AD (difference in mean annual rate of change: -0.91; 95% confidence interval [CI]: -1.68, -0.14). VaD participants also declined at a slower rate than DLB participants, but this difference was not statistically significant (-0.61; 95% CI: -1.45, 0.24). There was no significant difference between DLB and AD. Within each group, rate of decline was more rapid for the youngest participants.

CONCLUSIONS

In this sample, findings suggested that VaD patients declined in their functional abilities at a slower rate compared with AD patients and that there were no significant differences in rate of functional decline between patients with DLB compared with those with either AD or VaD. These results may provide guidance to clinicians about average expected rates of functional decline in three common dementia types.

African Americans with memory loss: findings from a community clinic in Lexington, Kentucky

Kentucky's African-American Dementia Outreach Partnership (AADOP) has shown that African-American patients seek dementia care if a clinic is conveniently located and families are educated about the distinction between normal aging and signs of disease. The early identification of dementia allows African Americans access to pharmaceutic treatments that work best early in the course of the disease and provides the opportunity for the patient to plan future care. In the AADOP model, a conveniently located clinic and access to the patient's home were first steps in achieving equality of care. The trust that was built in the community through collaboration with African-American churches has allowed patients and their families to receive help with memory problems and to feel comfortable in seeking help for other medical problems. Maintaining this involvement and responsiveness to the community over the long term is the next challenge for the program.

Long-term cognitive transitions, rates of cognitive change, and predictors of incident dementia in a population-based first-ever stroke cohort

BACKGROUND AND PURPOSE

There are few data on long-term cognitive outcomes after first-ever stroke. We aimed to study long-term cognitive transitions, rates of cognitive change, and factors associated with incident dementia and cognitive impairment-no dementia (CIND) 2 years after first-ever stroke.

METHODS

A population-based cohort of incident first-ever stroke cases (n=99; mean age, 69.9 years) and an age- and sex-matched comparison group (nonstrokes, n=99) were followed up for 2 years by 3 serial examinations. Rates of cognitive change were compared by repeated-measures analyses. Factors associated with incident dementia and CIND at 2 years were determined by multinomial logistic regression.

RESULTS

Significant stroke x time interactions were present for all cognitive domains, with stroke cases showing a greater rate of decline compared with nonstrokes. Stroke recurrence during follow-up was responsible for significantly greater global decline. Strokes with recurrence (P=0.02), age (P=0.004), and baseline cognitive impairment (P<0.001) were independently associated with incident dementia at 2 years. Strokes without recurrence (P=0.008), age (P=0.001), and baseline cognitive impairment (P<0.001) were independently associated with CIND at 2 years.

CONCLUSIONS

Recurrent stroke contributes importantly to global cognitive decline after a first-ever stroke. Secondary stroke prevention will be important in ameliorating dementia related to stroke. Mechanisms underlying the progression of early cognitive impairment to dementia in stroke patients need further investigation.

Epidemiology of stroke in African Americans and Hispanic Americans

Many minorities continue to experience disparities in the level of their personal health and overall health care in the United States. This article explores disparities in stroke as they relate to two minority populations: African Americans and Hispanic Americans. These two groups have been chosen for review and discussion because the available epidemiologic databases are relatively broad, and the authors have personal experience in the conduct of research studies in these populations.