Vascular pathology and pathogenesis of cognitive impairment and dementia in older adults

Cerebrospinal fluid biomarker profiling of diverse pathophysiological domains in Alzheimer's disease

INTRODUCTION

While Alzheimer's disease (AD) is defined by amyloid-β plaques and tau tangles in the brain, it is evident that many other pathophysiological processes such as inflammation, neurovascular dysfunction, oxidative stress, and metabolic derangements also contribute to the disease process and that varying contributions of these pathways may reflect the heterogeneity of AD. Here, we used a previously validated panel of cerebrospinal fluid (CSF) biomarkers to explore the degree to which different pathophysiological domains are dysregulated in AD and how they relate to each other.

METHODS

Twenty-five CSF biomarkers were analyzed in individuals with a clinical diagnosis of AD verified by positive CSF AD biomarkers (AD, n = 54) and cognitively unimpaired controls negative for CSF AD biomarkers (CU-N, n = 26) using commercial single- and multi-plex immunoassays.

RESULTS

We noted that while AD was associated with increased levels of only three biomarkers (MMP-10, FABP3, and 8OHdG) on a group level, half of all AD participants had increased levels of biomarkers belonging to at least two pathophysiological domains reflecting the diversity in AD. LASSO modeling showed that a panel of FABP3, 24OHC, MMP-10, MMP-2, and 8OHdG constituted the most relevant and minimally correlated set of variables differentiating AD from CU-N. Interestingly, factor analysis showed that two markers of metabolism and oxidative stress (24OHC and 8OHdG) contributed independent information separate from MMP-10 and FABP3 suggestive of two independent pathophysiological pathways in AD, one reflecting neurodegeneration and vascular pathology, and the other associated with metabolism and oxidative stress.

DISCUSSION

Better understanding of the heterogeneity among individuals with AD and the different contributions of pathophysiological processes besides amyloid-β and tau will be crucial for optimizing personalized treatment strategies.

Highlights

A panel of 25 highly validated biomarker assays were measured in CSF.MMP10, FABP3, and 8OHdG were increased in AD in univariate analysis.Many individuals with AD had increased levels of more than one biomarker.Markers of metabolism and oxidative stress contributed to an AD multianalyte profile.Assessing multiple biomarker domains is important to understand disease heterogeneity.

Small vessel disease burden and functional brain connectivity in mild cognitive impairment

Background

The role of small vessel disease in the development of dementia is not yet completely understood. Functional brain connectivity has been shown to differ between individuals with and without cerebral small vessel disease. However, a comprehensive measure of small vessel disease quantifying the overall damage on the brain is not consistently used and studies using such measure in mild cognitive impairment individuals are missing.

Method

Functional brain connectivity differences were analyzed between mild cognitive impairment individuals with absent or low (n = 34) and high (n = 34) small vessel disease burden using data from the Parelsnoer Institute, a Dutch multicenter study. Small vessel disease was characterized using an ordinal scale considering: lacunes, microbleeds, perivascular spaces in the basal ganglia, and white matter hyperintensities. Resting state functional MRI data using 3 Tesla scanners was analyzed with group-independent component analysis using the CONN toolbox.

Results

Functional connectivity between areas of the cerebellum and between the cerebellum and the thalamus and caudate nucleus was higher in the absent or low small vessel disease group compared to the high small vessel disease group.

Conclusion

These findings might suggest that functional connectivity of mild cognitive impairment individuals with low or absent small vessel disease burden is more intact than in mild cognitive impairment individuals with high small vessel disease. These brain areas are mainly responsible for motor, attentional and executive functions, domains which in previous studies were found to be mostly associated with small vessel disease markers. Our results support findings on the involvement of the cerebellum in cognitive functioning.

Hypertension differentially impacts cognition in men and women in early midlife

The current study aimed to understand how sex differences in the timing of hypertension onset contribute to early midlife risk for cognitive decline that may differ by sex and whether sex-dependent advantages in normotensive populations are influenced by the presence of hypertension. One hundred and ninety-five adults aged 45-55 from the New England Family Study underwent neuropsychological testing to assess attention, executive function, and memory. Physician-diagnosed hypertension status was self-reported via questionnaire. Mid-adulthood hypertension was associated with worse performance on measures of attention and memory, but the cognitive domains impacted varied by sex. Hypertension was associated with only attention in men, whereas in women it was associated with attention and associative and working memory. Sex differences in midlife cognitive performance found in normotensive adults were attenuated in those with hypertension. Our results underscore the importance of accounting for sex when assessing the impact of hypertension on midlife cognition that could be indicative of later decline and risk for cognitive impairment and dementia, given hypertension is an independent risk factor.

[Pathogenetic therapy of cognitive impairment: results of a multicenter placebo-controlled clinical trial of the efficacy and safety of Miladean]

OBJECTIVE

Evaluation of the efficacy and safety of the use of the drug Miladean in the treatment of patients with cognitive disorders (CDs) of vascular genesis.

MATERIAL AND METHODS

In during the double-blind multicenter prospective randomized placebo-controlled phase III clinical trial, 300 patients with CDs and chronic cerebral ischemia were randomized into 3 groups: group 1 (n=100) received Miladean (daily dose: memantine 10 mg + melatonin 6 mg), group 2 (n=101) - memantine (10 mg/day), group 3 - placebo (n=99) for 8 weeks. The dynamics of the overall score (the primary criterion of effectiveness) and the proportion of patients with improvement on the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog), the dynamics of visual-spatial orientation disorders (Benton test), sleep quality (Pittsburgh Sleep Quality Index scale) and the safety of therapy were evaluated.

RESULTS

Miladean demonstrated efficacy in the treatment of CDs: a statistically and clinically significant decrease in the overall score on the ADAS-Sod scale was shown (by 6.1 versus 4.7 and 3.5 points in the 2nd (p=0.009) and 3rd (p<0.05) groups) and an increase in the proportion of patients (96.9%) with clinically and statistically a significant improvement compared to the 2nd and 3rd groups (p=0.019 and p<0.001 respectively). Miladean significantly improved the performance in the Benton test (1.20±1.66 vs. 0.64±1.69 points in group 3, p=0.026) and sleep quality (84.7% of patients with CDs), compared to placebo (63.9%) and memantine (64.3%) (p=0.002 in both cases). Miladean was well tolerated, there were no cases of interaction with basic therapy drugs.

CONCLUSION

The combination of many different pathogenetic effects of Miladean suggests that it has the ability to slow down the rate of progression of CDs and stabilize the condition of patients. The unique combination of active substances in Miladean has been proven to be effective and safe in the treatment of patients with CDs.

Interaction between Alzheimer's Disease and Cerebral Small Vessel Disease: A Review Focused on Neuroimaging Markers

Alzheimer's disease (AD) is characterized by the presence of β-amyloid (Aβ) and tau, and subcortical vascular cognitive impairment (SVCI) is characterized by cerebral small vessel disease (CSVD). They are the most common causes of cognitive impairment in the elderly population. Concurrent CSVD burden is more commonly observed in AD-type dementia than in other neurodegenerative diseases. Recent developments in Aβ and tau positron emission tomography (PET) have enabled the investigation of the relationship between AD biomarkers and CSVD in vivo. In this review, we focus on the interaction between AD and CSVD markers and the clinical effects of these two markers based on molecular imaging studies. First, we cover the frequency of AD imaging markers, including Aβ and tau, in patients with SVCI. Second, we discuss the relationship between AD and CSVD markers and the potential distinct pathobiology of AD markers in SVCI compared to AD-type dementia. Next, we discuss the clinical effects of AD and CSVD markers in SVCI, and hemorrhagic markers in cerebral amyloid angiopathy. Finally, this review provides both the current challenges and future perspectives for SVCI.