Blood pressure and brain injury in older adults: findings from a community-based autopsy study

FOXO3 longevity genotype attenuates the impact of hypertension on cerebral microinfarct risk

OBJECTIVE

The G -allele of FOXO3 SNP rs2802292 , which is associated with human resilience and longevity, has been shown to attenuate the impact of hypertension on the risk of intracerebral hemorrhage (ICH). We sought to determine whether the FOXO3 G -allele similarly attenuates the impact of hypertension on the risk of cerebral microinfarcts (CMI).

METHODS

From a prospective population-based cohort of American men of Japanese ancestry from the Kuakini Honolulu Heart Program (KHHP) and Kuakini Honolulu-Asia Aging Study (KHAAS) that had brain autopsy data, age-adjusted prevalence of any CMI on brain autopsy was assessed. Logistic regression models, adjusted for age at death, cardiovascular risk factors, FOXO3 and APOE-ε4 genotypes, were utilized to determine the predictors of any CMI. Interaction of FOXO3 genotype and hypertension was analyzed.

RESULTS

Among 809 men with complete data, 511 (63.2%) participants had evidence of CMI. A full multivariable model demonstrated that BMI [odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01-1.14, P  = 0.015) was the only predictor of CMI, while hypertension was a borderline predictor (OR 1.44, 95% CI 1.00-2.08, P  = 0.052). However, a significant interaction between FOXO3 G -allele carriage and hypertension was observed ( P  = 0.020). In the stratified analyses, among the participants without the longevity-associated FOXO3 G -allele, hypertension was a strong predictor of CMI (OR 2.25, 95% CI 1.34-3.77, P  = 0.002), while among those with the longevity-associated FOXO3 G -allele, hypertension was not a predictor of CMI (OR 0.88, 95% CI 0.51-1.54, P  = 0.66).

CONCLUSION

The longevity-associated FOXO3 G -allele mitigates the impact of hypertension on the risk of CMI.

Relationship between Cerebral Microinfarcts and Dementia by Sex: Findings from a community-based Autopsy Study

Cerebral microinfarcts are common in older adults and are associated with cognitive impairment. Less is known about sex-related variation in the relationship between cerebral microinfarcts and dementia in older adults, the examination of which was the objective of this study. This case-control study was based on the 727 participants (419 women) in the Adult Changes in Thought (ACT) autopsy data. Microinfarcts were ascertained by blinded board-certified neuropathologists, and dementia diagnoses were made by the ACT Consensus Diagnosis Conference per DSM-IV. Multivariable logistic regression models were used to estimate adjusted odds ratio (aOR) and 95% confidence interval (CI). Microinfarcts were present in 49% (356/727) of the participants, which was numerically higher in women: 51% (213/419) vs 46% (143/308). aOR (95% CI) for dementia associated with any microinfarct for female and male participants were 1.45 (0.91-2.30) and 1.24 (0.75-2.06), respectively (p for interaction, 0.34). Respective aORs (95%CIs) associated with ≥2 microinfarcts were 1.37 (0.79-2.36) and 1.53 (0.84-2.78), with interaction p, 0.84. Subcortical microinfarcts were present in 36% (138/381) and 23% (78/346) of patients with and without dementia (aOR, 1.65; 95% CI, 1.14-2.38). Respective aOR (95% CI) in female and male participants were 1.70 (1.03-2.82) and 1.59 (0.90-2.80), (p for interaction, 0.55). There was no association with cortical microinfarcts (aOR, 1.19; 95% CI, 0.83-1.69). These findings suggest that association between microinfarcts and dementia is primarily mediated by subcortical microinfarcts, but we found no evidence of sex-related variation. Future studies with greater power are needed to determine if the associations we found are replicable.

Self-Reported Late-Life Hypertension Is Associated with a Healthy Cognitive Status and Reduced Alzheimer's Disease Pathology Burden

Background

While mid-life hypertension represents a risk factor for the development of Alzheimer's disease (AD), the risk after the age of 65 is less certain. Establishing relationships between late life hypertension and the pathological changes of AD could be crucial in understanding the relevance of blood pressure as a risk factor for this disorder.

Objective

We investigated associations between self-reported late-life hypertension, cognitive status and AD pathology at death. The impact of antihypertensive medication was also examined.

Methods

Using the Cornell Medical Index questionnaire, we ascertained whether participants had ever reported hypertension. We also noted use of antihypertensive medication. The donated brains of 108 individuals were assessed for AD pathology using consensus guidelines. Statistical analysis aimed to elucidate relationships between hypertension and AD pathology.

Results

We found no associations between self-reported hypertension and cognitive impairment at death. However, those with hypertension were significantly more likely to exhibit lower levels of AD pathology as measured by Thal phase, Braak stage, CERAD score, and NIA-AA criteria-even after controlling for sex, level of education and presence of APOEɛ4 allele(s). No significant associations could be found when examining use of antihypertensive medications.

Conclusions

Our findings suggest that late-life hypertension is associated with less severe AD pathology. We postulate that AD pathology may be promoted by reduced cerebral blood flow.

Relationships between Late-Life Blood Pressure and Cerebral Microinfarcts in Octogenarians: An Observational Autopsy Study

Mid-life high blood pressure (BP) is a risk factor for cerebral microinfarcts. Less is known about the relationship between late-life BP and cerebral microinfarcts, the examination of which is the objective of the current study. This case-control study analyzed data from 551 participants (94.6% aged ≥80 years; 58.6% women) in the Adult Changes in Thought (ACT) study who had autopsy data on microinfarcts and four values of systolic and diastolic blood pressure (SBP and DBP) before death. Using the average of four values, SBP was categorized using 10 mmHg intervals; a trend was defined as a ≥10 mmHg rise or fall from the first to fourth values (average gap of 6.5 years). Multivariable-adjusted regression models were used to examine the associations of BP and microinfarcts, adjusting for age, sex, last BP-to-death time, APOE genotype, and antihypertensive medication use. Microinfarcts were present in 274 (49.7%) participants; there were multiple in 51.8% of the participants, and they were located in cortical areas in 40.5%, subcortical areas in 29.6%, and both areas in 29.9% of the participants. All SBP categories (reference of 100-119 mmHg) and both SBP trends were associated with higher odds of both the presence and number of microinfarcts. The magnitude of these associations was numerically greater for subcortical than cortical microinfarcts. Similar associations were observed with DBP. These hypothesis-generating findings provide new information about the overall relationship between BP and cerebral microinfarcts in octogenarians.

Synergistic interaction of high blood pressure and cerebral beta-amyloid on tau pathology

BACKGROUND

Hypertension has been associated with Alzheimer's disease (AD) dementia as well as vascular dementia. However, the underlying neuropathological changes that link hypertension to AD remain poorly understood. In our study, we examined the relationships of a history of hypertension and high current blood pressure (BP) with in vivo AD pathologies including β-amyloid (Aβ) and tau and also investigated whether a history of hypertension and current BP respectively affect the association between Aβ and tau deposition.

METHODS

This cross-sectional study was conducted as part of the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer's Disease, a prospective cohort study. Cognitively normal older adults who underwent both Aβ and tau positron emission tomography (PET) (i.e., [¹¹C]-Pittsburgh compound B and [¹⁸F] AV-1451 PET) were selected. History of hypertension and current BP were evaluated and cerebral Aβ and tau deposition measured by PET were used as main outcomes. Generalized linear regression models were used to estimate associations.

RESULTS

A total of 68 cognitively normal older adults (mean [SD] age, 71.5 [7.4] years; 40 women [59%]) were included in the study. Neither a history of hypertension nor the current BP exhibited a direct association with Aβ or tau deposition. However, the synergistic interaction effects of high current systolic (β, 0.359; SE, 0.141; p = 0.014) and diastolic (β, 0.696; SE, 0.158; p < 0.001) BP state with Aβ deposition on tau deposition were significant, whereas there was no such effect for a history of hypertension (β, 0.186; SE, 0.152; p = 0.224).

CONCLUSIONS

The findings suggest that high current BP, but not a history of hypertension, synergistically modulate the relationship between cerebral Aβ and tau deposition in late-life. In terms of AD prevention, the results support the importance of strict BP control in cognitively normal older adults with hypertension.

Hypertension and Alzheimer's disease pathology at autopsy: A systematic review

Hypertension is an important risk factor for Alzheimer's disease (AD) and all-cause dementia. The mechanisms underlying this association are unclear. Hypertension may be associated with AD neuropathological changes (ADNC), but reports are sparse and inconsistent. This systematic review included 15 autopsy studies (n = 5879) from observational cohorts. Studies were highly heterogeneous regarding populations, follow-up duration, hypertension operationalization, neuropathological methods, and statistical analyses. Hypertension seems associated with higher plaque and tangle burden, but results are inconsistent. Four studies (n = 3993/5879; 68%), reported clear associations between hypertension and ADNC. Another four suggested that antihypertensive medication may protect against ADNC. Larger studies with longer follow-up reported the strongest relationships. Our findings suggest a positive association between hypertension and ADNC, but effects may be modest, and possibly attenuate with higher hypertension age and antihypertensive medication use. Investigating interactions among plaques, tangles, cerebrovascular pathology, and dementia may be key in better understanding hypertension's role in dementia development.

Association of cardiovascular risk burden with risk of dementia and brain pathologies: A population-based cohort study

INTRODUCTION

The impact of cardiovascular risk burden on brain pathologies remains unclear. We aimed to examine the association of the Framingham General Cardiovascular Risk Score (FGCRS) with dementia risk, and brain pathologies.

METHODS

Within the Rush Memory and Aging Project, 1588 dementia-free participants were assessed on FGCRS at baseline and followed up to 21 years. During the follow-up, 621 participants died and underwent autopsies.

RESULTS

The multi-adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) of FGCRS were 1.03 (1.00-1.07) for dementia and 1.04 (1.01-1.07) for Alzheimer's disease (AD) dementia. Further, a higher FGCRS was associated with higher gross chronic cerebral infarctions (odds ratio [OR] 1.08, 95% CI 1.02-1.14), cerebral atherosclerosis (OR 1.10, 95% CI 1.03-1.17), and global AD pathology (OR 1.06, 95% CI 1.01-1.12).

CONCLUSIONS

A higher FGCRS is associated with an increased risk of dementia and AD dementia. Both vascular and AD pathologies in the brain may underlie this association.

Cognitive Impairment in Older Adults and Therapeutic Strategies

Cognitive impairment and its severe form dementia are increasingly prevalent in older adults and loom as a public health disaster unless effective interventions are developed. Cognitive impairment is a convergent trait caused by damage from an idiosyncratic mix of four prevalent diseases (Alzheimer disease; vascular brain injury; Lewy body diseases, such as Parkinson disease and dementia with Lewy bodies; and limbic-predominant age-related transactive response DNA-binding protein 43 encephalopathy) that is counterbalanced by individually varying resilience, which is comprised of reserve and compensation. Brain regional damage from each of these four prevalent diseases is generated by the net effect of injury and (mal)adaptive response and is accompanied by characteristic lesions. Existing therapeutics enhance resilience, whereas most agents under development target mechanisms of damage with only suppression of vascular brain injury yet to show therapeutic promise. We hope to anticipate future tailored interventions that target mechanisms of damage and thereby avert the oncoming surge of cognitive impairment and dementia in older adults. SIGNIFICANCE STATEMENT: Brain regional damage is generated by the net effect of injury and (mal)adaptive response. The extent to which signs and symptoms of such damage occur is influenced by an underlying resilience comprising reserve and compensation. Finding tailored interventions that target specific mechanisms of damage likely yields the most effective therapies.

Association of midlife vascular risk and AD biomarkers with subsequent cognitive decline

OBJECTIVE

To determine whether vascular risk and Alzheimer disease (AD) biomarkers have independent or synergistic effects on cognitive decline and whether vascular risk is associated with the accumulation of AD pathology as measured by change in biomarkers over time.

METHODS

At baseline, participants (n = 168) were cognitively normal and primarily middle-aged (mean 56.4 years, SD 10.9 years) and had both vascular risk factor status and proximal CSF biomarkers available. Baseline vascular risk was quantified with a composite vascular risk score reflecting the presence or absence of hypertension, hypercholesterolemia, diabetes, current smoking, and obesity. CSF biomarkers of β-amyloid (Aβ)_1-42, total tau (t-tau), and phosphorylated tau (p-tau) were used to create dichotomous high and low AD biomarker groups (based on Aβ_1-42 and tau). Linear mixed-effects models were used to examine change in a cognitive composite score (mean follow-up 13.9 years) and change in CSF biomarkers (mean follow-up 4.2 years).

RESULTS

There was no evidence of a synergistic relationship between the vascular risk score and CSF AD biomarkers and cognitive decline. Instead, the vascular risk score (estimate -0.022, 95% confidence interval [CI] -0.043 to -0.002, p = 0.03) and AD biomarkers (estimate -0.060, 95% CI -0.096 to -0.024, p = 0.001) were independently and additively associated with cognitive decline. In addition, the vascular risk score was unrelated to levels of or rate of change in CSF Aβ_1-42, t-tau, or p-tau.

CONCLUSIONS

The results of this observational cohort study suggest that vascular risk and biomarkers of AD pathology, when measured in midlife, act along independent pathways and underscore the importance of accounting for multiple risk factors for identifying cognitively normal individuals at the greatest risk of cognitive decline.

Cortical Microinfarcts Associated With Worse Outcomes in Patients With Acute Ischemic Stroke Receiving Endovascular Treatment

BACKGROUND AND PURPOSE

We aimed to evaluate the impact of cortical microinfarcts (CMIs) on functional outcome after endovascular treatment in patients with acute ischemic stroke.

METHODS

In a multicenter registration study for RESCUE-RE (a registration study for Critical Care of Acute Ischemic Stroke After Recanalization), eligible patients with large vessel occlusion stroke receiving endovascular treatment, who had undergone 3T magnetic resonance imaging on admission or within 24 hours after endovascular treatment were analyzed. We evaluated the presence and numbers of CMIs with assessment of axial T1, T2-weighted images, and fluid-attenuated inversion recovery images. The primary outcome was functional dependence or death defined as modified Rankin Scale scores of 3 to 6 at 90 days. Secondary outcomes included early neurological improvement, any intracranial hemorrhage, symptomatic intracranial hemorrhage, and mortality. We investigated the independent associations of CMIs with the outcomes using multivariable logistic regression in overall patients and in subgroups.

RESULTS

Among 414 patients (enrolled from July 2018 to May 2019) included in the analyses, 96 (23.2%) patients had at least one CMI (maximum 6). Patients with CMI(s) were more likely to be functionally dependent or dead at 90 days, compared with those without (55.2% versus 37.4%; P<0.01). In multivariable logistic regression analyses, presence of CMI(s) (adjusted odds ratio, 1.78 [95% CI, 1.04-3.07]; P=0.04) and multiple CMIs (CMIs ≥2; adjusted odds ratio, 7.41 [95% CI, 2.48-22.17]; P<0.001) were independently, significantly associated with the primary outcome. There was no significant difference between subgroups in the associations between CMI presence and the primary outcome.

CONCLUSIONS

Acute large vessel occlusion stroke patients receiving endovascular treatment with CMI(s) were more likely to have a poor functional outcome at 90 days, independent of patients' characteristics. Such associations may be dose-dependent. Registration: URL: http://www.chictr.org.cn; Unique identifier: ChiCTR1900022154.

Antihypertensive medications ameliorate Alzheimer's disease pathology by slowing its propagation

INTRODUCTION

Mounting evidence supports an association between antihypertensive medication use and reduced risk of Alzheimer's disease (AD). Consensus on possible pathological mechanisms remains elusive.

METHODS

Human brain tissue from a cohort followed to autopsy that included 96 cases of AD (46 medicated for hypertension) and 53 pathological controls (33 also medicated) matched for cerebrovascular disease was available from the New South Wales Brain Banks. Quantified frontal cortex amyloid beta (Aβ) and tau proteins plus Alzheimer's neuropathologic change scores were analyzed.

RESULTS

Univariate analyses found no difference in amounts of AD proteins in the frontal cortex between medication users, but multivariate analyses showed that antihypertensive medication use was associated with a less extensive spread of AD proteins throughout the brain.

DISCUSSION

The heterogeneous nature of the antihypertensive medications is consistent with downstream beneficial effects of blood pressure lowering and/or management being associated with the reduced spreading of AD pathology observed.

Association Between Sepsis and Microvascular Brain Injury

OBJECTIVES

Many survivors of sepsis suffer long-term cognitive impairment, but the mechanisms of this association remain unknown. The objective of this study was to determine whether sepsis is associated with cerebral microinfarcts on brain autopsy.

DESIGN

Retrospective cohort study.

SETTING AND SUBJECTS

Five-hundred twenty-nine participants of the Adult Changes in Thought, a population-based prospective cohort study of older adults carried out in Kaiser Permanente Washington greater than or equal to 65 years old without dementia at study entry and who underwent brain autopsy.

MEASUREMENTS AND MAIN RESULTS

Late-life sepsis hospitalization was identified using administrative data. We identified 89 individuals with greater than or equal to 1 sepsis hospitalization during study participation, 80 of whom survived hospitalization and died a median of 169 days after discharge. Thirty percent of participants with one or more sepsis hospitalization had greater than two microinfarcts, compared with 19% participants without (χ p = 0.02); 20% of those with sepsis hospitalization had greater than two microinfarcts in the cerebral cortex, compared with 10% of those without (χ p = 0.01). The adjusted relative risk of greater than two microinfarcts was 1.61 (95% CI, 1.01-2.57; p = 0.04); the relative risk for having greater than two microinfarcts in the cerebral cortex was 2.12 (95% CI, 1.12-4.02; p = 0.02). There was no difference in Braak stage for neurofibrillary tangles or consortium to establish a registry for Alzheimer's disease score for neuritic plaques between, but Lewy bodies were less significantly common in those with sepsis.

CONCLUSIONS

Sepsis was specifically associated with moderate to severe vascular brain injury as assessed by microvascular infarcts. This association was stronger for microinfarcts within the cerebral cortex, with those who experienced severe sepsis hospitalization being more than twice as likely to have evidence of moderate to severe cerebral cortical injury in adjusted analyses. Further study to identify mechanisms for the association of sepsis and microinfarcts is needed.

Associations of decision making abilities with blood pressure values in older adults

OBJECTIVES

Decision making, key to successful aging, has implications for financial success, physical health, and well being. While poor decision making has been linked with increased risk of mortality, age-related cognitive decline, and dementia, less is known regarding its associations with chronic disease indicators. We investigated the associations of decision making with blood pressure (BP) values [i.e., SBP, mean arterial pressure (MAP), and pulse pressure (PP), separately] in a community-based cohort study of aging.

METHODS

Participants were 908 nondemented older adults (age ∼81 years; 75% women) from the Rush Memory and Aging Project. Decision making was measured using questions designed to simulate materials used in financial and healthcare settings in the real world and yielded a total score and domain-specific health and financial decision making scores. Two seated and one standing BP measurement were taken with all three contributing to average SBP, MAP that is, [SBP + (2 × DBP)]/3, and PP, that is, SBP - DBP. Participants were queried about hypertension status and antihypertension medications were visually inspected and coded. Participants also underwent medical history and cognitive assessments.

RESULTS

In separate multivariable linear regression models, total decision making scores were inversely associated with SBP, MAP, and PP after adjusting for age, sex, education, antihypertension medication use, diabetes, and cumulative cardiovascular disease burden (P values = 0.03). Decision making remained associated with these BP values after additional adjustment for global cognition.

CONCLUSION

Poorer decision making is associated with higher BP values in nondemented older adults.

Association Between Microinfarcts and Blood Pressure Trajectories

Importance

Cerebral microinfarcts are associated with increased risk of cognitive impairment and may have different risk factors than macroinfarcts. Subcortical microinfarcts are associated with declining blood pressure (BP) in elderly individuals.

Objective

To investigate BP slopes as a risk factor for microinfarcts.

Design, Setting, and Participants

From the population-based Mayo Clinic Study of Aging, 303 of 1158 individuals (26.2%) in this cohort study agreed to have an autopsy between November 1, 2004, and March 31, 2016. Cerebral microinfarcts were identified and classified as cortical or subcortical. Baseline and BP trajectories were compared for groups with no microinfarcts, subcortical microinfarcts, and cortical microinfarcts. A secondary logistic regression analysis was performed to assess associations of subcortical microinfarcts with midlife hypertension, as well as systolic and diastolic BP slopes.

Main Outcomes and Measures

The presence of cerebral microinfarcts using BP slopes.

Results

Of the 303 participants who underwent autopsy, 297 had antemortem BP measurements. Of these, 177 (59.6%) were men; mean (SD) age at death was 87.2 (5.3) years. The autopsied individuals and the group who died but were not autopsied were similar for all demographics except educational level with autopsied participants having a mean of 1 more year of education (1.06; 95% CI, 0.66-1.47 years; P < .01). Among 297 autopsied individuals with antemortem BP measurements, 47 (15.8%) had chronic microinfarcts; 30 (63.8%) of these participants were men. Thirty (63.8%) had cortical microinfarcts, 19 (40.4%) had subcortical microinfarcts, and 4 (8.5%) had only infratentorial microinfarcts. Participants with microinfarcts did not differ significantly on baseline systolic (mean difference, -1.48; 95% CI, -7.30 to 4.34; P = .62) and diastolic (mean difference of slope, -0.90; 95% CI, -3.93 to 2.13; P = .56) BP compared with those with no microinfarcts. However, participants with subcortical microinfarcts had a greater annual decline (negative slope) of systolic (mean difference of slope, 4.66; 95% CI, 0.13 to 9.19; P = .04) and diastolic (mean difference, 3.33; 95% CI, 0.61 to 6.06; P = .02) BP.

Conclusions and Relevance

Subcortical microinfarcts were associated with declining BP. Future studies should investigate whether declining BP leads to subcortical microinfarcts or whether subcortical microinfarcts are a factor leading to declining BP.

Risk Factors Associated with Cortical Thickness and White Matter Hyperintensities in Dementia Free Okinawan Elderly

Background:

Cortical gray matter (GM) and white matter (WM) deterioration are signals of neurodegeneration and increased dementia risk; however, their specific etiologies in dementia-free aging is unclear.

Objective:

The objective of this study was to examine potentially modifiable risk factors of GM and WM degeneration in a well-characterized cohort of dementia-free elderly.

Methods:

96 Okinawan elderly participants (age 83.6) from the Keys to Optimal Cognitive Aging Project (KOCOA) underwent MRI and cognitive evaluation. Serum markers of inflammation (interleukin-6 (IL-6), high sensitivity C-reactive protein), cerebrovascular disease (systolic blood pressure (SBP) 140+, hemoglobin A1C (HgbA1C), total cholesterol), and essential minerals (copper (Cu), magnesium, and calcium) were examined in relation to mean cortical thickness (MCT) and white matter hyperintensities (WMH), adjusting for age and gender. Voxel-based morphometry (VBM) analyses identified relationships between regional GM density and the above markers.

Results:

Decreased MCT was associated with SBP 140 + (p = 0.029) and increased serum IL-6 (p = 0.036), HgbA1C (p = 0.002), and Cu (p = 0.025). In VBM analyses, increased IL-6, HgbA1C, and Cu were associated with decreased GM density in temporal lobe regions. HgbA1C (p = 0.004) was associated with greater WMH volume.

Conclusions:

Peripheral markers of Cu, CVD risk, and inflammation are associated with MRI-markers of decreased brain health in dementia-free Okinawan elderly, with regional cortical thinning in areas involved in early accumulation of Alzheimer’s disease pathology. Results identify potentially modifiable biomarkers as targets in the prevention of dementia in older individuals.

Asymptomatic Cerebral Small Vessel Disease: Insights from Population-Based Studies

Cerebral small vessel disease (CSVD) is a common group of neurological conditions that confer a significant burden of morbidity and mortality worldwide. In most cases, CSVD is only recognized in its advanced stages once its symptomatic sequelae develop. However, its significance in asymptomatic healthy populations remains poorly defined. In population-based studies of presumed healthy elderly individuals, CSVD neuroimaging markers including white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, cortical superficial siderosis, and cerebral microinfarcts are frequently detected. While the presence of these imaging markers may reflect unique mechanisms at play, there are likely shared pathways underlying CSVD. Herein, we aim to assess the etiology and significance of these individual biomarkers by focusing in asymptomatic populations at an epidemiological level. By primarily examining population-based studies, we explore the risk factors that are involved in the formation and progression of these biomarkers. Through a critical semi-systematic review, we aim to characterize “asymptomatic” CSVD, review screening modalities, and draw associations from observational studies in clinical populations. Lastly, we highlight areas of research (including therapeutic approaches) in which further investigation is needed to better understand asymptomatic CSVD.

Late-life blood pressure association with cerebrovascular and Alzheimer disease pathology

OBJECTIVE

To examine associations of average and change in late-life blood pressure (BP) with cerebrovascular and Alzheimer disease (AD) neuropathology in a large group of decedents followed longitudinally in vivo.

METHODS

This clinical-pathologic study was derived from prospective, community-based cohort studies of aging with similar design and data collection. Measurements of systolic BP (SBP) and diastolic BP (DBP) were obtained annually (mean follow-up 8 years, SD = 4.8). Postmortem neuropathologic evaluations documented diseases of aging. Using regression analyses, we examined associations of average and decline in late-life SBP, and separately in DBP, with neuropathology.

RESULTS

In 1,288 persons (mean age at death = 88.6 years; 65% women), the mean standardized person-specific SBP across the study was 134 (SD = 13) and DBP was 71 (SD = 8) mm Hg. The odds of brain infarcts were increased for participants with a higher mean SBP. Specifically, a person with a 1 SD SBP above the mean (147 vs 134 mm Hg) would have a 46% increased odds of having one or more infarcts, and an increased odds of gross infarct (46%) and microinfarct (36%). Furthermore, a more rapidly declining SBP slope over time increased the odds of one or more infarcts. Mean DBP, not slope, was related to brain infarcts. AD pathology analyses showed an association of a higher mean SBP with higher number of tangles (p = 0.038) but not plaques or other pathology (all p > 0.06). Changes in BP were not significantly related to AD pathology.

CONCLUSIONS

Higher average late-life SBP and DBP, and independently a faster decline in SBP, are associated with increasing number of brain infarcts, including gross and microinfarcts. We found some evidence for a relation of SBP with AD, specifically tangles. Both average and decline in BP are related to brain disease.

The growing clinical spectrum of cerebral amyloid angiopathy

PURPOSE OF REVIEW

Cerebral amyloid angiopathy (CAA) is diagnosed primarily as a cause of lobar intracerebral hemorrhages (ICH) in elderly patients. With improving MRI techniques, however, the role of CAA in causing other symptoms has become clear. Recognizing the full clinical spectrum of CAA is important for diagnosis and treatment. In this review we summarize recent insights in clinical CAA features, MRI biomarkers, and management.

RECENT FINDINGS

The rate of ICH recurrence in CAA is among the highest of all stroke subtypes. Cortical superficial siderosis (cSS) and cortical subarachnoid hemorrhage (cSAH) are important imaging predictors for recurrent ICH. CAA also causes cognitive problems in multiple domains. In patients with nondemented CAA, the risk of developing dementia is high especially after ICH. CAA pathology probably starts years before the first clinical manifestations. The first signs in hereditary CAA are white matter lesions, cortical microinfarcts, and impaired occipital cerebral vasoreactivity. Visible centrum semiovale perivascular spaces, lobar located lacunes, and cortical atrophy are new nonhemorrhagic MRI markers.

SUMMARY

CAA should be in the differential diagnosis of elderly patients with lobar ICH but also in those with cognitive decline and episodic transient neurological symptoms. Physicians should be aware of the cognitive effects of CAA. In patients with a previous ICH, cSS, or cSAH, anticoagulation should be considered risky. The increasing number of MRI markers may help to discriminate CAA from other small vessel diseases and dementia subtypes.

Watershed microinfarct pathology and cognition in older persons

Brain microinfarcts are common in aging and are associated with cognitive impairment. Anterior and posterior watershed border zones lie at the territories of the anterior, middle, and posterior cerebral arteries, and are more vulnerable to hypoperfusion than brain regions outside the watershed areas. However, little is known about microinfarcts in these regions and how they relate to cognition in aging. Participants from the Rush Memory and Aging Project, a community-based clinical-pathologic study of aging, underwent detailed annual cognitive evaluations. We examined 356 consecutive autopsy cases (mean age-at-death, 91 years [SD = 6.16]; 28% men) for microinfarcts from 3 watershed brain regions (2 anterior and 1 posterior) and 8 brain regions outside the watershed regions. Linear regression models were used to examine the association of cortical watershed microinfarcts with cognition, including global cognition and 5 cognitive domains. Microinfarcts in any region were present in 133 (37%) participants, of which 50 had microinfarcts in watershed regions. Persons with multiple microinfarcts in cortical watershed regions had lower global cognition (estimate = -0.56, standard error (SE) = 0.26, p = 0.03) and lower cognitive function in the specific domains of working memory (estimate = -0.58, SE = 0.27, p = 0.03) and visuospatial abilities (estimate = -0.57, SE = 0.27, p = 0.03), even after controlling for microinfarcts in other brain regions, demographics, and age-related pathologies. Neither the presence nor multiplicity of microinfarcts in brain regions outside the cortical watershed regions were related to global cognition or any of the 5 cognitive domains. These findings suggest that multiple microinfarcts in watershed regions contribute to age-related cognitive impairment.

Cerebrospinal fluid biomarkers for Alzheimer's and vascular disease vary by age, gender, and APOE genotype in cognitively normal adults

BACKGROUND

This study sought to evaluate gender and APOE genotype-related differences in the concentrations of cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) and cerebrovascular injury across the life span of cognitively normal adults.

METHODS

CSF amyloid beta_1-42 (Aβ₄₂), phospho-tau-181 (p-tau₁₈₁), and total tau were measured in 331 participants who were between the ages of 21 and 100. CSF E-selectin and vascular cell adhesion protein 1 (VCAM1) were measured in 249 participants who were between the ages of 50 and 100.

RESULTS

CSF total tau and p-tau₁₈₁ increased with age over the adult life span (p < 0.01) with no gender differences in those increases. CSF Aβ₄₂ concentration varied according to age, gender, and APOE genotype (interaction of age × gender × ε4, p = 0.047). CSF VCAM1, but not E-selectin, increased with age (p < 0.01), but both were elevated in men compared to women (p < 0.01).

CONCLUSIONS

Female APOE-ε4 carriers appear at higher risk for AD after age 50. In contrast, men may experience a relatively higher rate of cerebrovascular injury in middle and early old age.

Impact of Hypertension on Cognitive Function: A Scientific Statement From the American Heart Association

BACKGROUND

Age-related dementia, most commonly caused by Alzheimer disease or cerebrovascular factors (vascular dementia), is a major public health threat. Chronic arterial hypertension is a well-established risk factor for both types of dementia, but the link between hypertension and its treatment and cognition remains poorly understood. In this scientific statement, a multidisciplinary team of experts examines the impact of hypertension on cognition to assess the state of the knowledge, to identify gaps, and to provide future directions.

METHODS

Authors with relevant expertise were selected to contribute to this statement in accordance with the American Heart Association conflict-of-interest management policy. Panel members were assigned topics relevant to their areas of expertise, reviewed the literature, and summarized the available data.

RESULTS

Hypertension disrupts the structure and function of cerebral blood vessels, leads to ischemic damage of white matter regions critical for cognitive function, and may promote Alzheimer pathology. There is strong evidence of a deleterious influence of midlife hypertension on late-life cognitive function, but the cognitive impact of late-life hypertension is less clear. Observational studies demonstrated a cumulative effect of hypertension on cerebrovascular damage, but evidence from clinical trials that antihypertensive treatment improves cognition is not conclusive.

CONCLUSIONS

After carefully reviewing the literature, the group concluded that there were insufficient data to make evidence-based recommendations. However, judicious treatment of hypertension, taking into account goals of care and individual characteristics (eg, age and comorbidities), seems justified to safeguard vascular health and, as a consequence, brain health.

Increased CSF E-Selectin in Clinical Alzheimer's Disease without Altered CSF Aβ42 and Tau

Clinically diagnosed Alzheimer's disease (AD) is pathologically heterogeneous. In this multicenter cohort of 215 clinically diagnosed AD patients and 249 controls, E-selectin and vascular cell adhesion molecule 1 (VACM-1) were measured along with amyloid-β peptide 1-42 (Aβ42) and tau. We discovered that E-selectin, a biomarker of endothelial function/vascular injury, was inversely correlated with cerebrospinal fluid (CSF) tau/Aβ42 ratio and significantly elevated in clinical AD patients without the typical AD CSF biomarker signature (i.e., low tau/Aβ42 ratio) compared to those with the signature. These findings suggest that E-selectin may be an objective biomarker related to vascular mechanisms contributing to dementia.

Microinfarcts are common and strongly related to dementia in the oldest-old: The 90+ study

INTRODUCTION

We estimated the prevalence of microinfarcts and their association with dementia in a cohort of oldest-old participants.

METHODS

Participants were from The 90+ Study, a population-based study of people 90 years and older. Dementia diagnoses were assigned postmortem during a consensus conference. Microinfarcts were evaluated in six brain regions.

RESULTS

At death, the 213 participants were on average 97 years old, 69% were women, and 52% had dementia. Of the participants, 51% had microinfarcts and 17% had 3+ microinfarcts. The odds ratio (OR) for dementia was similar for 3+ microinfarcts (OR = 4.75, P < .01) and tangle stage V-VI (OR = 4.70, P < .001). Only microinfarcts in cortical regions (other than occipital) were associated to dementia.

DISCUSSION

In this oldest-old cohort, microinfarcts are common and contribute independently and similarly in magnitude to dementia as tangles. As risk factors for microinfarcts and other dementing pathologies are likely to differ, identifying these factors is crucial to developing prevention strategies for dementia in the oldest-old.

Vascular contributions to cognitive impairment, clinical Alzheimer's disease, and dementia in older persons

There is growing evidence suggesting that vascular pathologies and dysfunction play a critical role in cognitive impairment, clinical Alzheimer's disease, and dementia. Vascular pathologies such as macroinfarcts, microinfarcts, microbleeds, small and large vessel cerebrovascular disease, and white matter disease are common especially in the brains of older persons where they contribute to cognitive impairment and lower the dementia threshold. Vascular dysfunction resulting in decreased cerebral blood flow, and abnormalities in the blood brain barrier may also contribute to the Alzheimer's disease (AD) pathophysiologic process and AD dementia. This review provides a clinical-pathological perspective on the role of vessel disease, vascular brain injury, alterations of the neurovascular unit, and mixed pathologies in the Alzheimer's disease pathophysiologic process and Alzheimer's dementia. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

The Development of Cortical Microinfarcts Is Associated with Intracranial Atherosclerosis: Data from the Chinese Intracranial Atherosclerosis Study

BACKGROUND

Little is known about the association between the cortical microinfarcts (CMIs) and intracranial atherosclerosis (ICAS) in Chinese patients with ischemic stroke. This study was designed to analyze the association and evaluate the role of CMIs in clinical outcomes.

METHODS

We evaluated 1421 consecutive patients who had experienced an acute cerebral ischemia within 7 days after symptom onset and evaluated the presence of CMIs and ICAS based on patients' 3.0-T magnetic resonance imaging and magnetic resonance angiography scans. Baseline characteristics, patient risk factors, and clinical outcomes were analyzed to investigate the different outcomes between the CMIs (n = 209) group and non-CMIs (n = 1212) group.

RESULTS

CMIs were present in 14.7% persons. The following parameters were associated with risk of CMIs: advanced age, National Institutes of Health Stroke Scale score on admission, lower level of systemic blood pressure, lower triglycerides level, ICAS, and cerebral microbleeds (CMBs). On multivariate logistic regression analysis, ICAS remained an independent risk factor for the development of CMIs (adjusted odds ratio, 1.493; 95% confidence interval, 1.022-2.182; P = .038). At the time point of 1 year after stroke, the rates of poor outcome (modified Rankin Scale, 3-6) in CMIs group (33.5%) were statistically significantly different from the non-CMIs group (22.6%; P = .001). In addition, patients in CMIs group had a significantly higher stroke recurrence rate than patients in the non-CMIs group (6.7% versus 4%; P = .085).

CONCLUSIONS

The development of CMIs is strongly associated with ICAS. CMIs are independent predictors of poor prognosis in patients with ischemic stroke.

Stroke risk interacts with Alzheimer's disease biomarkers on brain aging outcomes

Alzheimer's disease (AD) biomarkers and stroke risk factors independently predict cognitive impairment, likely through independent disease pathways. However, limited work has sought to describe the dynamic interplay between these important risk factors. This article evaluated the interaction between stroke risk and AD biomarkers on hippocampal volume and cognitive performance. We first evaluated the interaction between stroke risk factors and AD biomarkers using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI, n = 1202). We then extended our findings to an independent autopsy data set from the National Alzheimer's Coordinating Center (NACC, n = 1122) using measures of AD pathology. Stroke risk was quantified using the Framingham Stroke Risk Profile. In ADNI, stroke risk interacted with tau and amyloid levels in relation to baseline and longitudinal cognitive performance. Similarly, in NACC, stroke risk interacted with amyloid and tau positivity on cognitive performance. The effect of stroke risk factors on cognition was strongest in the absence of AD biomarkers or neuropathology, providing additional evidence that AD biomarkers and stroke risk factors relate to cognition through independent pathways.

Factors associated with morphometric brain changes in cognitively normal aging

OBJECTIVE

Cognitive impairment is associated with reductions in brain weight and volume. The factors related to morphometric brain changes in cognitively normal aging remain unknown. We aimed to identify which clinical factors are associated with morphometric brain changes in cognitively normal aging.

METHODS

A cross-sectional study of 414 subjects, ≥50 years old submitted to clinical assessment and brain autopsy, after informed consent, was carried out at the São Paulo Autopsy Service, Brazil. Data on cognitive and functional evaluations were collected through structured interview applied to the next-of-kin. Brain weight (g) and volume (mL) measurements were obtained and adjusted for head circumference (cm). Associations between brain weight/volume and related factors were obtained through univariate and multivariate analysis.

RESULTS

Participants were predominantly male (60.4%), Caucasian (69%), with mean age of 67.1 ± 10.9 years. Mean brain weight was 1219.2 ± 140.9 g, and mean brain volume was 1217.1 ± 152.3 mL. Head circumference was independently associated with low brain weight (p<0.001) and volume (p<0.001). Total and adjusted brain weight and volume decreased in some conditions. Female gender (p<0.001), hypertension (p<0.009), coronary artery disease (p<0.013) and walking assistance (p<0.011) were associated with lower adjusted brain weight while schooling was associated with higher adjusted brain weight (p<0.003). Female gender (p<0.001), age (p<0.001) and hypertension (p<0.011) were associated with low adjusted brain volume.

CONCLUSION

Morphometric brain changes occur despite the absence of cognitive impairment and were predominantly associated with age, female gender, mobility impairment and cardiovascular conditions. Schooling may be a protective factor.

Vascular and amyloid pathologies are independent predictors of cognitive decline in normal elderly

Vemuri et al. show that amyloid and vascular pathologies are independent processes, and that both are major drivers of cognitive decline in the elderly. Cognitive reserve as measured by educational/occupational level and mid/late-life cognitive activity seems to offset the deleterious effects of both pathologies on cognitive trajectories.

Our primary objective was to investigate a biomarker driven model for the interrelationships between vascular disease pathology, amyloid pathology, and longitudinal cognitive decline in cognitively normal elderly subjects between 70 and 90 years of age. Our secondary objective was to investigate the beneficial effect of cognitive reserve on these interrelationships. We used brain amyloid-β load measured using Pittsburgh compound B positron emission tomography as a marker for amyloid pathology. White matter hyperintensities and brain infarcts were measured using fluid-attenuated inversion recovery magnetic resonance imaging as a marker for vascular pathology. We studied 393 cognitively normal elderly participants in the population-based Mayo Clinic Study of Aging who had a baseline 3 T fluid-attenuated inversion recovery magnetic resonance imaging assessment, Pittsburgh compound B positron emission tomography scan, baseline cognitive assessment, lifestyle measures, and at least one additional clinical follow-up. We classified subjects as being on the amyloid pathway if they had a global cortical amyloid-β load of ≥1.5 standard uptake value ratio and those on the vascular pathway if they had a brain infarct and/or white matter hyperintensities load ≥1.11% of total intracranial volume (which corresponds to the top 25% of white matter hyperintensities in an independent non-demented sample). We used a global cognitive z-score as a measure of cognition. We found no evidence that the presence or absence of vascular pathology influenced the presence or absence of amyloid pathology and vice versa, suggesting that the two processes seem to be independent. Baseline cognitive performance was lower in older individuals, in males, those with lower education/occupation, and those on the amyloid pathway. The rate of cognitive decline was higher in older individuals (P < 0.001) and those with amyloid (P = 0.0003) or vascular (P = 0.0037) pathologies. In those subjects with both vascular and amyloid pathologies, the effect of both pathologies on cognition was additive and not synergistic. For a 79-year-old subject, the predicted annual rate of global z-score decline was −0.02 if on neither pathway, −0.07 if on the vascular pathway, −0.08 if on the amyloid pathway and −0.13 if on both pathways. The main conclusions of this study were: (i) amyloid and vascular pathologies seem to be at least partly independent processes that both affect longitudinal cognitive trajectories adversely and are major drivers of cognitive decline in the elderly; and (ii) cognitive reserve seems to offset the deleterious effect of both pathologies on the cognitive trajectories.

Cardiorespiratory fitness mediates the effects of aging on cerebral blood flow

The brain's vasculature is likely to be subjected to the same age-related physiological and anatomical changes affecting the rest of the cardiovascular system. Since aerobic fitness is known to alleviate both cognitive and volumetric losses in the brain, it is important to investigate some of the possible mechanisms underlying these beneficial changes. Here we investigated the role that estimated cardiorespiratory fitness (eCRF) plays in determining the relationship between aging and cerebral blood flow (CBF) in a group of older adults (ages 55–85). Using arterial spin labeling to quantify CBF, we found that blood flow in the gray matter was positively correlated with eCRF and negatively correlated with age. Subsequent analyses revealed that eCRF fully mediated the effects of age on CBF in the gray matter, but not in the white matter. Additionally, regional measures of CBF were related to regional measures of brain volume. These findings provide evidence that age-related effects on cerebrovascular health and perfusion in older adults are largely influenced by their eCRF levels.

Neuropathologic correlates of cognition in a population-based sample

Many cognitively normal older adults have underlying neuropathologic changes of Alzheimer's disease (AD), vascular brain injury (VBI), or Lewy body disease (LBD), which confer an increased risk of dementia. The current study focused on the association between multiple neuropathologic indices and performance on specific cognitive domains in a community sample of older adults. Of 438 participants in the Adult Changes in Thought population-based study of brain aging who were autopsied, 363 subjects had cognitive testing at their final study visit and were included. Associations were measured between performance on the Cognitive Abilities Screening Instrument prior to death and neuropathologic endpoints, including AD neuropathologic changes, LBD, cerebral amyloid angiopathy, and measures of VBI. Braak stage for neurofibrillary tangles, lower brain weight, and VBI as measured by cerebral cortical microvascular lesions (μVBI) explained a significant proportion of the variance associated with global cognitive test performance (R2 = 0.31, p < 0.0001) both in the entire sample and when analysis was restricted to non-demented subjects (R2 = 0.23, p < 0.0001). Specific cognitive domains were differentially related to neuropathologic lesion type: memory and executive function with AD pathologic changes and cortical μVBI, executive function with subcortical μVBI, and visuospatial construction with LBD. Thus, neuropathologic lesions of LBD and μVBI are associated with poorer cognitive performance over and above AD neuropathologic changes in subjects without dementia in this cohort. These findings underscore that cognitive impairment is a complex convergent trait that has important implications for clinical investigation and medical management of older adults.

Impact of gender and blood pressure on poststroke cognitive decline among older Latinos

BACKGROUND

Poststroke cognitive decline (PSCD) is an important consequence of stroke that may be more severe in women than in men. The existence of any gender differences in PSCD among Mexican Americans, and their potential mechanisms, such as blood pressure (BP), remain unknown. We assessed PSCD stratified on gender in older Mexican Americans and explored the influence of pre- and poststroke systolic BP on PSCD.

METHODS

Among 1576 nondemented, stroke-free adults 60 years of age or older when recruited between 1998 and 1999 in the Sacramento Area Latino Study on Aging (SALSA) cohort, we examined pre- and poststroke longitudinal changes in Spanish English Verbal Learning test scores (WL), a verbal memory test, and errors on the Modified Mini Mental State Examination (3MSE) scores, a global cognition test, stratified by gender, adjusting for baseline and time-varying covariates with linear mixed effects models.

RESULTS

We identified 151 adults (mean age 72 ± 8 years) with incident first-ever stroke during 10 years of follow-up. After adjustment for age, education, and time-varying depressive symptoms, 3MSE errors increased by 22% per year (95% confidence interval [CI] 6.8-36.7%) in men and 13.2% per year (95% CI 3.5-22.9%) in women over the poststroke period. Poststroke WL scores improved by 0.05 words per year (95% CI -0.24 to 0.33) in men and by 0.09 words per year (95% CI -0.16 to 0.34) in women. Results persisted after adjustment for time-varying systolic BP.

CONCLUSIONS

Among this population of older Mexican Americans, PSCD did not differ by gender. We found no evidence that systolic BP influenced PSCD in women or men.

Antihypertensive medication use and risk of cognitive impairment: the Honolulu-Asia Aging Study

OBJECTIVE

To determine the associations between classes of antihypertensive medication use and the risk of cognitive impairment among elderly hypertensive men.

METHODS

The Honolulu-Asia Aging Study is a prospective, community-based cohort study of Japanese American men conducted in Honolulu, Hawaii. We examined 2,197 participants (mean age 77 years at cohort entry, 1991-1993, followed through September 2010) with hypertension and without dementia or cognitive impairment at baseline, who provided information on medication use. Cognitive function was assessed at 7 standardized examinations using the Cognitive Abilities Screening Instrument (CASI). Cognitive impairment was defined as a CASI score <74.

RESULTS

A total of 854 men developed cognitive impairment (median follow-up, 5.8 years). β-Blocker use as the sole antihypertensive drug at baseline was consistently associated with a lower risk of cognitive impairment (incidence rate ratio [IRR] 0.69; 95% confidence interval [CI] 0.50-0.94), as compared with men not taking any antihypertensive medications, adjusting for multiple potential confounders. The use of diuretics, calcium channel blockers, angiotensin-converting enzyme inhibitors, or vasodilators alone was not significantly associated with cognitive impairment. Results were similar excluding those with cardiovascular disease or <1 year of follow-up, and additionally adjusting for pulse pressure, heart rate, baseline and midlife systolic blood pressure, and midlife antihypertensive treatment (IRR 0.65; 95% CI 0.45-0.94). The association between β-blocker use and cognitive impairment was stronger among men with diabetes, men aged >75 years, and those with pulse pressure ≥70 mm Hg.

CONCLUSIONS

β-blocker use is associated with a lower risk of developing cognitive impairment in elderly Japanese American men.

The Honolulu-Asia Aging Study: epidemiologic and neuropathologic research on cognitive impairment

The Honolulu-Asia Aging Study (HAAS) is a longitudinal epidemiologic investigation of rates, risk factors, and neuropathologic abnormalities associated with cognitive decline and dementia in aged Japanese-American men. The project was established in 1991 and will be brought to closure in 2012. Age-specific rates of total dementia and the major specific types of dementia in HAAS participants are generally similar to those reported from other geographic, cultural, and ethnic populations. Risk factors for dementia in the HAAS include midlife hypertension and other factors previously shown to influence cardiovascular disease. The autopsy component of the project has yielded novel findings, the most illuminating of which is the demonstration of 5 important lesion types linked independently to cognitive impairment. While one of these--generalized atrophy--is strongly associated with both Alzheimer lesions and microinfarcts, it also occurs in the absence of these lesions and is independently correlated with dementia. Each lesion type is viewed as representing a distinct underlying pathogenic process. Their summed influences is an especially robust correlate of dementia in the months and years prior to death.

Pathology of lacunar ischemic stroke in humans--a systematic review

Twenty-five percent of ischemic strokes are lacunar in type, but the cause remains unclear. Pathological descriptions of lacunar lesions are available but have not been systematically assessed. We therefore systematically summarized studies describing lacunar lesions by extracting data on the number of patients and lesions, clinical details, pathological methods, brain regions and/or vessels examined, and both parenchymal and vascular findings. Among 39 papers describing >4000 lesions (>50% from one study), 15 papers examined patients with a clinical lacunar syndrome. Terminology varied, many studies only reported macroscopic pathology and many lesions were cavitated (ie, old). Aside from symptomatic lesions occurring more often in the internal capsule or caudate nucleus, we found no other differences between symptomatic and asymptomatic patients. Perivascular edema and thickening, inflammation and disintegration of the arteriolar wall were common, whereas vessel occlusion was rare. The causal mechanisms of lacunar stroke remain poorly defined because of methodological inconsistencies and challenges. Standardised pathological definitions based on well-characterized post-mortem derived material supported by detailed clinical and imaging data are needed.

Cerebral microinfarcts: a systematic review of neuropathological studies

Vascular cognitive impairment is an umbrella term for cognitive dysfunction associated with and presumed to be caused by vascular brain damage. Autopsy studies have identified microinfarcts as an important neuropathological correlate of vascular cognitive impairment that escapes detection by conventional magnetic resonance imaging (MRI). As a frame of reference for future high-resolution MRI studies, we systematically reviewed the literature on neuropathological studies on cerebral microinfarcts in the context of vascular disease, vascular risk factors, cognitive decline and dementia. We identified 32 original patient studies involving 10,515 people. The overall picture is that microinfarcts are common, particularly in patients with vascular dementia (weighted average 62%), Alzheimer's disease (43%), and demented patients with both Alzheimer-type and cerebrovascular pathology (33%) compared with nondemented older individuals (24%). In many patients, multiple microinfarcts were detected. Microinfarcts are described as minute foci with neuronal loss, gliosis, pallor, or more cystic lesions. They are found in all brain regions, possibly more so in the cerebral cortex, particularly in watershed areas. Reported sizes vary from 50 μm to a few mm, which is within the detection limit of current high-resolution MRI. Detection of these lesions in vivo would have a high potential for future pathophysiological studies in vascular cognitive impairment.

Cerebral microinfarcts: the invisible lesions

The association between small but still visible lacunar infarcts and cognitive decline has been established by population-based radiological and pathological studies. Microscopic examination of brain sections shows even smaller but substantially more numerous microinfarcts, the focus of this Review. These lesions often result from small vessel pathologies such as arteriolosclerosis or cerebral amyloid angiopathy. They typically go undetected in clinical-radiological correlation studies that rely on conventional structural MRI, although the largest acute microinfarcts can be detected by diffusion-weighted imaging. In view of their high numbers and widespread distribution, microinfarcts could directly disrupt important cognitive networks and thus account for some of the neurological dysfunction associated with lesions visible on conventional MRI such as lacunar infarcts and white matter hyperintensities. Standardised neuropathological assessment criteria and the development of non-invasive means of detection during life would be major steps towards understanding the causes and consequences of otherwise macroscopically invisible microinfarcts.

Blood pressure responses to hypertension treatment and trends in cognitive function in patients with initially difficult-to-treat hypertension: a retrospective subgroup analysis of the Observational Study on Cognitive Function and SBP Reduction (OSCAR) study

The Observational Study on Cognitive Function and SBP Reduction (OSCAR) provided opportunities to examine the influence of eprosartan on trends in cognitive performance in a large population of patients with difficult-to-treat hypertension (DTTH). A total of 4649 patients diagnosed retrospectively with DTTH, defined as systolic/diastolic blood pressure (SBP/DBP) ≥140/90 mm Hg despite use of at least 3 antihypertensive drugs during the month preceding the baseline visit comprised the intention-to-treat (ITT) cohort. The patients were given eprosartan-based antihypertension therapy (EBT; 600 mg/d). Blood pressure and cognitive function parameters included significant (P<.001) differences for DTTH vs non-DTTH patients such as older age, body mass index, SBP and pulse pressure (PP), and lower Mini-Mental State Examination (MMSE) score. After EBT for 6 months, SBP/DBP in DTTH was 138.8±12.2/81.9±7.4 (ΔSBP-26±15.7; ΔDBP-11.4±9.8); PP was 57.0±10.8 (ΔPP-14.5±13.8) (all P<.001 vs baseline and non-DTTH group). A total of 2576 patients (87.4%) responded to EBT (ie, SBP <140 mm Hg and/or ΔSBP ≥15 mm Hg, or DBP <90 mm Hg and/or ΔDBP ≥10 mm Hg); 1426 DTTH patients (48.4%) achieved normalized SBP/DBP (ie, SBP <140 mm Hg and DBP <90 mm Hg). ΔPP in DTTH-isolated systolic hypertension (ISH) was -18.0±13.3 mm Hg (P=.003 vs DTTH-systolic-diastolic hypertension). End-of-EBT mean MMSE was 27.5±3.0 (P<.001 vs baseline). Blood pressure responses after EBT coincided with stabilization/improvement of MMSE in this retrospective investigation in DTTH patients. The average improvement in MMSE in DTTH patients was similar to that in non-DTTH patients. EBT effects on PP may be relevant to the evolution of MMSE in DTTH-ISH patients.

Vascular risk factors and Alzheimer's disease: are these risk factors for plaques and tangles or for concomitant vascular pathology that increases the likelihood of dementia? An evidence-based review

Recent epidemiologic studies have noted that risk factors for atherosclerosis (for example, diabetes mellitus, hypertension, and hyperlipidemia) are associated with increased risk of incident Alzheimer's disease (AD). In this evidence-based review, we frame the proposition as a question: are vascular risk factors also risk factors for plaques and tangles or just for concomitant vascular pathology that increases the likelihood of dementia? To date, no representative, prospective studies with autopsy (evidence level A) show significant positive associations between diabetes mellitus, hypertension, or intracranial atherosclerosis and plaques or tangles. Some prospective, representative, epidemiologic studies (evidence level B) show associations between diabetes, hypertension, hyperlipidemia, and aggregated risk factors with clinically diagnosed incident AD. However, the strength of association diminishes in the following order: vascular dementia (VaD) > AD + VaD > AD. This pattern is arguably more consistent with the hypothesis that atherosclerosis promotes subclinical vascular brain injury, thereby increasing the likelihood of dementia and in some cases making symptoms present earlier. Several autopsy studies from AD brain banks (evidence level C) have observed positive associations between intracranial atherosclerosis and severity of plaques and tangles. However, these studies may reflect selection bias; these associations are not confirmed when cases are drawn from non-dementia settings. We conclude that, at the present time, there is no consistent body of evidence to show that vascular risk factors increase AD pathology.

Vascular cognitive impairment: disease mechanisms and therapeutic implications

The prevalence of vascular cognitive impairment (VCI) is likely to increase as the population ages and cardiovascular disease survival improves. We provide an overview of the definition and disease mechanisms of VCI and present a systematic literature review of the current evidence for the pharmacologic and nonpharmacologic therapies used to treat the VCI symptoms of cognitive dysfunction or to modify VCI through primary and secondary prevention. The Cochrane Database of Systematic Reviews was searched from 2005 to October 2010 using the keywords "vascular dementia" or "vascular cognitive impairment and therapy." MEDLINE was searched for English-language articles published within the last 10 years using the combined Medical Subject Headings (MeSH) "therapeutics and dementia," "vascular" or "vascular cognitive impairment." Although cholinesterase inhibitors and memantine produce small cognitive improvements in patients with VCI, these drugs do not improve global clinical outcomes and have adverse effects and costs. Selective serotonin reuptake inhibitors and dihydropyridine calcium channel blockers may improve short-term cognitive function in patients with VCI. Anti-hypertensive therapy with an ACE inhibitor-based regimen and statins may prevent the major subtype of VCI known as poststroke cognitive decline. Clinical and effectiveness studies with long-term follow-up are needed to determine the benefits and risks of pharmacologic and nonpharmacologic therapies to prevent and treat VCI. Given its growing health, social, and economic burden, the prevention and treatment of VCI are critical priorities for clinical care and research.

Alzheimer's disease markers, hypertension, and gray matter damage in normal elderly

It is not well known whether Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers are associated with brain damage in cognitively normal elderly. The combined influence of CSF biomarkers and hypertension (HTN) on the gray matter (GM) is also not well described. One hundred fifteen cognitively healthy subjects (mean age 62.6 ± 9.5%, 62% women) received clinical assessment, a high resolution magnetic resonance imaging (MRI), and a lumbar puncture. The CSF levels of total tau (t-tau), hyperphosphorylated tau (p-tau(231)), amyloid beta (Aβ42/Aβ40), p-tau(231)/Aβ42, and t-tau/Aβ42 were dichotomized as "high" and "low" based on accepted cut off values. Statistical parametric mapping was used to examine MRI scans for regional GM density, studied as a function of the CSF markers, HTN, and combination of both. Global and medial temporal lobe (MTL) GM was also assessed. Voxel based morphometry revealed that higher t-tau was associated with lower GM density in the precunei. Subjects with higher p-tau(231) and p-tau(231)/Aβ42 had less GM in temporal lobes. Low Aβ42/Aβ40 was related to less GM in the thalami, caudate, and midbrain. Subjects with hypertension showed more GM atrophy in the cerebellum, occipital, and frontal regions. Simultaneous presence of elevated CSF AD biomarkers and HTN was associated with more GM atrophy than either marker individually, but no interaction effects were identified. In conclusion, in normal elderly CSF tau markers were associated predominantly with lower GM estimates in structures typically affected early in the AD process. In this presymptomatic stage when no cognitive impairment is present, AD biomarkers and HTN have additive effects on gray matter damage.

Review: cerebral microvascular pathology in ageing and neurodegeneration

This review of age-related brain microvascular pathologies focuses on topics studied by this laboratory, including anatomy of the blood supply, tortuous vessels, venous collagenosis, capillary remnants, vascular density and microembolic brain injury. Our studies feature thick sections, large blocks embedded in celloidin, and vascular staining by alkaline phosphatase. This permits study of the vascular network in three dimensions, and the differentiation of afferent from efferent vessels. Current evidence suggests that there is decreased vascular density in ageing, Alzheimer's disease and leukoaraiosis, and cerebrovascular dysfunction precedes and accompanies cognitive dysfunction and neurodegeneration. A decline in cerebrovascular angiogenesis may inhibit recovery from hypoxia-induced capillary loss. Cerebral blood flow is inhibited by tortuous arterioles and deposition of excessive collagen in veins and venules. Misery perfusion due to capillary loss appears to occur before cell loss in leukoaraiosis, and cerebral blood flow is also reduced in the normal-appearing white matter. Hypoperfusion occurs early in Alzheimer's disease, inducing white matter lesions and correlating with dementia. In vascular dementia, cholinergic reductions are correlated with cognitive impairment, and cholinesterase inhibitors have some benefit. Most lipid microemboli from cardiac surgery pass through the brain in a few days, but some remain for weeks. They can cause what appears to be a type of vascular dementia years after surgery. Donepezil has shown some benefit. Emboli, such as clots, cholesterol crystals and microspheres can be extruded through the walls of cerebral vessels, but there is no evidence yet that lipid emboli undergo such extravasation.

Prospects for delaying the rising tide of worldwide, late-life dementias

Worldwide, lifespan is lengthening. Concomitantly, late-life dementias are increasingly common, challenging both personal and public health internationally. After age 65, rates of dementia tend to double every five years in developed countries and every seven in developing ones. The late-life dementias, particularly Alzheimer's disease, have profound effects on aging individuals and their caregivers. Multidisciplinary research has explored the potential for various approaches to prevent or delay the onset of late-life dementias. Outlining that research, including our team's Adult Changes in Thought and Kame studies, this review concludes that delaying the onset of these dementias appears feasible, although absolute prevention may not be. Today, the most promising methods appear to include controlling vascular risk factors like hypertension and engaging in physical exercise - and possibly mental exercise. If people can delay the onset of dementias, they can lead more fulfilling lives for longer, spending less time suffering from dementia and letting their families spend less time coping with the disease. It is possible that trends toward more knowledge-based societies, where cognitive health is so vital, may increasingly exert evolutionary pressure favoring larger and healthier brains - and a "compression of cognitive morbidity" - well into old age. Public health's great triumph, increased lifespan, should give more of the world's people the reward of many years of dementia-free life. Rather than the personal difficulties and public health burdens of many years of functional impairment, dependency, and suffering with dementia, some interventions may delay the onset of Alzheimer's disease and other dementias.

Metabolic-cognitive syndrome: a cross-talk between metabolic syndrome and Alzheimer's disease

A growing body of epidemiological evidence suggested that metabolic syndrome (MetS) and Mets components (impaired glucose tolerance, abdominal or central obesity, hypertension, hypertriglyceridemia, and reduced high-density lipoprotein cholesterol) may be important in the development of age-related cognitive decline (ARCD), mild cognitive impairment (MCI), vascular dementia, and Alzheimer's disease (AD). These suggestions proposed in these patients the presence of a "metabolic-cognitive syndrome", i.e. a MetS plus cognitive impairment of degenerative or vascular origin. This could represent a pathophysiological model in which to study in depth the mechanisms linking MetS and MetS components with dementia, particularly AD, and predementia syndromes (ARCD or MCI), suggesting a possible integrating view of the MetS components and their influence on cognitive decline. In the present article, we discussed the role of these factors in the development of cognitive decline and dementia, including underlying mechanisms, supporting their influence on β-amyloid peptide metabolism and tau protein hyperphosphorylation, the principal neuropathological hallmarks of AD. In the next future, trials could then be undertaken to determine if modifications of these MetS components including inflammation, another factor probably related to MetS, could lower risk of developing cognitive decline. Future research aimed at identifying mechanisms that underlie comorbid associations of MetS components will not only provide important insights into the causes and interdependencies of predementia and dementia syndromes, but will also inspire novel strategies for treating and preventing cognitive disorders.