Lack of association between acute stroke, post-stroke dementia, race, and β-amyloid status

Independent effect of Aβ burden on cognitive impairment in patients with small subcortical infarction

BACKGROUND

The effect of amyloid-β (Aβ) on cognitive impairment in patients with small subcortical infarction remains controversial, although a growing body of evidence shows a substantial overlap between Alzheimer's disease (AD) and subcortical ischemic vascular dementia, another form of cerebral small vessel disease (cSVD). Therefore, we investigated the relationships between Aβ positivity and the development of post-stroke cognitive impairment (PSCI) in patients with small subcortical infarction.

METHODS

We prospectively recruited 37 patients aged ≥ 50 years, with first-ever small subcortical infarction, who underwent amyloid positron emission tomography, 3 months after stroke at Korea University Guro Hospital. We also enrolled CU participants matched for age and sex with stroke patients for comparison of Aβ positivity. Patients were followed up at 3 and 12 months after the stroke to assess cognitive decline. Logistic and linear mixed-effect regression analyses were performed to identify the effect of Aβ positivity on PSCI development and long-term cognitive trajectories.

RESULTS

At 3 months after stroke, 12/37 (32.4%) patients developed PSCI, and 11/37 (29.7%) patients had Aβ deposition. Aβ positivity (odds ratio [OR] = 72.2, p = 0.024) was predictive of PSCI development regardless of cSVD burden. Aβ positivity (β = 0.846, p = 0.014) was also associated with poor cognitive trajectory, assessed by the Clinical Dementia Rating-Sum of Box, for 1 year after stroke.

CONCLUSIONS

Our findings highlight that Aβ positivity is an important predictor for PSCI development and cognitive decline over 1 year. Furthermore, our results provide evidence that anti-AD medications may be a strategy for preventing cognitive decline in patients with small subcortical infarctions.

Are Ischemic Stroke and Alzheimer's Disease Genetically Consecutive Pathologies?

Complex diseases that affect the functioning of the central nervous system pose a major problem for modern society. Among these, ischemic stroke (IS) holds a special place as one of the most common causes of disability and mortality worldwide. Furthermore, Alzheimer's disease (AD) ranks first among neurodegenerative diseases, drastically reducing brain activity and overall life quality and duration. Recent studies have shown that AD and IS share several common risk and pathogenic factors, such as an overlapping genomic architecture and molecular signature. In this review, we will summarize the genomics and RNA biology studies of IS and AD, discussing the interconnected nature of these pathologies. Additionally, we highlight specific genomic points and RNA molecules that can serve as potential tools in predicting the risks of diseases and developing effective therapies in the future.

Cortical atrophy and leukoaraiosis, imaging markers of cerebrovascular small vessel disease, are associated with driving behavior changes among cognitively normal older adults

BACKGROUND

Cerebral small vessel disease (CSVD) as measured by cortical atrophy and white matter hyperintensities [leukoaraiosis], captured via magnetic resonance imaging (MRI) are increasing in prevalence due to the growth of the aging population and an increase in cardiovascular risk factors in the population. CSVD impacts cognitive function and mobility, but it is unclear if it affects complex, functional activities like driving.

METHODS

In a cohort of 163 cognitively normal, community-dwelling older adults (age ≥ 65), we compared naturalistic driving behavior with mild/moderate leukoaraiosis, cortical atrophy, or their combined rating in a clinical composite termed, aging-related changes to those without any, over a two-and-a-half-year period.

RESULTS

Older drivers with mild or moderate cortical atrophy and aging-related changes (composite) experienced a greater decrease in the number of monthly trips which was due to a decrease in the number of trips made within a one-to-five-mile diameter from their residence. Older drivers with CSVD experience a larger reduction in daily driving behaviors than drivers without CSVD, which may serve as an early neurobehavioral marker for functional decline.

CONCLUSIONS

As CSVD markers, leukoaraiosis and cortical atrophy are standard MRI metrics that are widely available and can be used for screening individuals at higher risk for driving safety risk and decline in community mobility.

Race‐related population attributable fraction of preventable risk factors of dementia: A Latino population‐based study

Background

Risk factors for dementia have distinct frequency and impact in relation to race. Our aim was to identify differences in modifiable risk factors of dementia related to races and estimate their population attributable fraction (PAF).

Methods

An epidemiological cohort was used to estimate the prevalence of 10 modifiable risk factors for dementia among five races—White, Black, Brown, Asian, and Indigenous. Sample weighting was used to estimate the prevalence and PAF of each risk factor in each race.

Results

A total of 9070 individuals were included. Overall adjusted PAF was the lowest in Indigenous (38.9%), and Asian individuals (41.2%). Race‐related prevalence of individual risk factors was widely variable in our population, but hearing loss was the most important contributor to the overall PAF in all races.

Conclusions

Public policies aiming to reduce preventable risk factors for dementia should take into consideration the race of the target populations.

HIGHLIGHTS

Preventable risk factors for dementia vary according to race.

Hearing loss presented the highest prevalence among all races studied.

Indigenous and Asian individuals presented the lowest population attributable fractions.

Black and Brown individuals were more vulnerable to social determinants.

Cognitive and brain reserve predict decline in adverse driving behaviors among cognitively normal older adults

Daily driving is a multi-faceted, real-world, behavioral measure of cognitive functioning requiring multiple cognitive domains working synergistically to complete this instrumental activity of daily living. As the global population of older adult continues to grow, motor vehicle crashes become more frequent among this demographic. Cognitive reserve (CR) is the brain's adaptability or functional robustness despite damage, while brain reserve (BR) refers the structural, neuroanatomical resources. This study examined whether CR and BR predicted changes in adverse driving behaviors in cognitively normal older adults. Cognitively normal older adults (Clinical Dementia Rating 0) were enrolled from longitudinal studies at the Knight Alzheimer's Disease Research Center at Washington University. Participants (n = 186) were ≥65 years of age, required to have Magnetic Resonance Imaging (MRI) data, neuropsychological testing data, and at least one full year of naturalistic driving data prior to the beginning of COVID-19 lockdown in the United States (March 2020) as measured by Driving Real World In-vehicle Evaluation System (DRIVES). Findings suggest numerous changes in driving behaviors over time were predicted by increased hippocampal and whole brain atrophy, as well as lower CR scores as proxied by the Wide Range Achievement Test 4. These changes indicate that those with lower BR and CR are more likely to reduce their driving exposure and limit trips as they age and may be more likely to avoid highways where speeding and aggressive maneuvers frequently occur.

Amyloid-Related Imaging Abnormalities with Emerging Alzheimer Disease Therapeutics: Detection and Reporting Recommendations for Clinical Practice

Monoclonal antibodies are emerging disease-modifying therapies for Alzheimer disease that require brain MR imaging for eligibility assessment as well as for monitoring for amyloid-related imaging abnormalities. Amyloid-related imaging abnormalities result from treatment-related loss of vascular integrity and may occur in 2 forms. Amyloid-related imaging abnormalities with edema or effusion are transient, treatment-induced edema or sulcal effusion, identified on T2-FLAIR. Amyloid-related imaging abnormalities with hemorrhage are treatment-induced microhemorrhages or superficial siderosis identified on T2* gradient recalled-echo. As monoclonal antibodies become more widely available, treatment screening and monitoring brain MR imaging examinations may greatly increase neuroradiology practice volumes. Radiologists must become familiar with the imaging appearance of amyloid-related imaging abnormalities, how to select an appropriate imaging protocol, and report findings in clinical practice. On the basis of clinical trial literature and expert experience from clinical trial imaging, we summarize imaging findings of amyloid-related imaging abnormalities, describe potential interpretation pitfalls, and provide recommendations for a standardized imaging protocol and an amyloid-related imaging abnormalities reporting template. Standardized imaging and reporting of these findings are important because an amyloid-related imaging abnormalities severity score, derived from the imaging findings, is used along with clinical status to determine patient management and eligibility for continued monoclonal antibody dosing.

Neuropathological and Clinical Correlates of Lewy Body Disease Survival by Race and Ethnicity in the National Alzheimer's Coordinating Center

BACKGROUND

Survival and associated clinical and pathological characteristics in Lewy body disease (LBD)-related dementias are understudied. Available studies focus primarily on white non-Hispanic samples.

OBJECTIVE

We investigated demographic, clinical, and pathological correlates of survival by race and ethnicity in an autopsy-confirmed cohort of LBD cases.

METHODS

Using National Alzheimer's Coordinating Center data, we selected participants who self-identified as Black, Hispanic, or white who had neuropathological assessments showing transitional or diffuse LBD pathology. We used Kruskal-Wallis and Pearson χ2 analyses to investigate group differences in demographic and presenting clinical and pathological characteristics. We used linear regressions to identify predictors of survival with sex, age at symptom onset, education, ethnoracial status, LBD pathology type, and Braak tangle stage included in the model.

RESULTS

Data from 1,441 white, 60 Black, and 54 Hispanic participants were available for analysis. Hispanics were more likely to have transitional LBD pathology and had a longer survival than white and Black participants. After controlling for demographic and pathological variables, length of survival did not differ between Hispanics and Black or white participants. Additional key findings demonstrated discrepancies between clinical diagnoses received at last visit and pathological findings, particularly among Black participants.

CONCLUSION

LBD survival differences by race and ethnicity can be accounted for by LBD pathology type and co-occurring Alzheimer's disease pathology. The discrepancies between clinical diagnoses and pathological findings raise the concern that dementia with Lewy bodies is underdiagnosed in NACC, especially for Black older adults.

Effects of cerebral artery thrombectomy on efficacy, safety, cognitive function and peripheral blood Aβ, IL-6 and TNF-α levels in patients with acute cerebral infarction

OBJECTIVE

Acute cerebral infarction (ACI) can lead to death or disability, posing a serious threat to human health. This study aimed to investigate the effects of cerebral artery thrombectomy on the efficacy, safety, cognitive function and peripheral blood amyloid-β (Aβ), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels in patients with ACI.

METHODS

The clinical data of 169 patients with ACI admitted to our hospital from April 2019 to September 2020 were analyzed retrospectively. Among them, 100 patients were treated with cerebral artery thrombectomy and assigned to the research group, and the other 69 patients were intervened by conventional treatment and assigned to the control group. The clinical effects in the two groups were observed and compared. The cognitive function was evaluated by the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment Scale (MoCA), the neurological dysfunction was assessed by the National Institutes of Health Stroke Scale (NIHSS), and the prognosis was determined by the Modified Rankin Scale (mRS). Peripheral blood Aβ1-40, Aβ1-42, IL-6 and TNF-α levels were determined using the enzyme-linked immunosorbent assay (ELISA). The incidence of adverse reactions and complications was statistically analyzed.

RESULTS

The overall response rate (ORR) was notably higher in the research group compared with the control group. Aβ1-40, Aβ1-42, IL-6 and TNF-α levels showed no significant difference between the two groups before treatment (P>0.05). After treatment, serum Aβ1-40 level was lower and Aβ1-42 was higher in the research group compared with the control group at each time point. Serum IL-6 level was markedly higher within 24 h while it was dramatically lower 24 h after treatment in the research group as compared with the control group. At 24 h, 7 d and 14 d after treatment, serum TNF-α level in the research group was lower than that in the control group (P<0.05). The MMSE and MoCA scores showed no significant differences between the two groups before treatment; however, the two scores in the research group were statistically higher than those in the control group after treatment. In addition, lower NIHSS and mRS scores were determined in the research group compared with the control group after treatment. Moreover, except for the statistically significant difference in the number of cases with cognitive dysfunction (P<0.05), there was no significant difference in the incidence of other adverse reactions between the research group and the control group (P>0.05).

CONCLUSIONS

Cerebral artery thrombectomy is effective in the treatment of ACI, which can improve the cognitive function of patients and alleviate the high Aβ accumulation and inflammation in the central nervous system, with a high safety profile.

Structural and Functional Deficits in Patients with Poststroke Dementia: A Multimodal MRI Study

Although many neuroimaging studies have reported structural and functional abnormalities in the brains of patients with cognitive impairments following stroke, little is known about the pattern of such brain reorganization in poststroke dementia (PSD). The present study was aimed at investigating alterations in spontaneous brain activity and gray matter volume (GMV) in PSD patients. We collected T1-weighted and resting-state functional magnetic resonance imaging data from 20 PSD patients, 24 poststroke nondementia (PSND) patients, and 21 well-matched normal controls (NCs). We compared the differences among the groups in GMV and the fractional amplitude of low-frequency fluctuations (fALFF). Then, we evaluated the relationship between these brain measures and cognitive assessments and explored the possible distinguisher for PSD by receiver operating characteristic (ROC) curve analysis. PSD patients showed smaller GMV in the right superior temporal gyrus and lower fALFF values in the right inferior frontal gyrus than both PSND patients and NCs, but such differences were not observed between PSND patients and NCs. Moreover, GMV in the left medial prefrontal cortex showed a significant positive correlation with the Mini-Cog assessment in PSD patients, and GMV in the left CPL displayed the highest area under the ROC curve among all the features for classifying PSD versus PSND patients. Our findings suggest that PSD patients show dementia-specific structural and functional alteration patterns, which may help elucidate the pathophysiological mechanisms underlying PSD.

Is Cerebral Amyloid-β Deposition Related to Post-stroke Cognitive Impairment?

Approximately two-thirds of ischemic stroke patients suffer from different levels of post-stroke cognitive impairment (PSCI), but the underlying mechanisms of PSCI remain unclear. Cerebral amyloid-β (Aβ) deposition, a pathological hallmark of Alzheimer's disease, has been discovered in the brains of stroke patients in some autopsy studies. However, less is known about the role of Aβ pathology in the development of PSCI. It is hypothesized that cerebral ischemic injury may lead to neurotoxic Aβ accumulation in the brain, which further induces secondary neurodegeneration and progressive cognitive decline after stroke onset. In this review, we summarized available evidence from pre-clinical and clinical studies relevant to the aforementioned hypothesis. We found inconsistency in the results obtained from studies in rodents, nonhuman primates, and stroke patients. Moreover, the causal relationship between post-stroke cerebral Aβ deposition and PSCI has been uncertain and controversial. Taken together, evidence supporting the hypothesis that brain ischemia induces cerebral Aβ deposition has been insufficient so far. And, there is still no consensus regarding the contribution of cerebral amyloid pathology to PSCI. Other non-amyloid neurodegenerative mechanisms might be involved and remain to be fully elucidated.

Mitophagy in Human Diseases

Mitophagy is a selective autophagic process, essential for cellular homeostasis, that eliminates dysfunctional mitochondria. Activated by inner membrane depolarization, it plays an important role during development and is fundamental in highly differentiated post-mitotic cells that are highly dependent on aerobic metabolism, such as neurons, muscle cells, and hepatocytes. Both defective and excessive mitophagy have been proposed to contribute to age-related neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, metabolic diseases, vascular complications of diabetes, myocardial injury, muscle dystrophy, and liver disease, among others. Pharmacological or dietary interventions that restore mitophagy homeostasis and facilitate the elimination of irreversibly damaged mitochondria, thus, could serve as potential therapies in several chronic diseases. However, despite extraordinary advances in this field, mainly derived from in vitro and preclinical animal models, human applications based on the regulation of mitochondrial quality in patients have not yet been approved. In this review, we summarize the key selective mitochondrial autophagy pathways and their role in prevalent chronic human diseases and highlight the potential use of specific interventions.