Skip to main content
Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Cerebral microbleed patterns and the risk of incident dementia in elderly adults: The ARIC study

  • Peng Zhang ,

    Contributed equally to this work with: Peng Zhang, Zhongrui Yan

    Roles Conceptualization, Data curation, Formal analysis, Methodology, Validation, Writing – original draft, Writing – review & editing

    zhangpeng4544@163.com (PZ); zhongruiy@163.com (ZY)

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Huakun Liu,

    Roles Data curation, Formal analysis, Funding acquisition, Visualization

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Xiaotan Ji,

    Roles Investigation, Methodology, Software, Supervision

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Jiuchang Zhang,

    Roles Investigation, Resources, Software, Validation, Visualization

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Yuling Cao,

    Roles Methodology, Resources, Supervision

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Xintan Zhang,

    Roles Project administration, Software

    Affiliation Department of Radiology, Jining No.1 People’s Hospital, Jining, Shandong, China

  • Zhongrui Yan

    Contributed equally to this work with: Peng Zhang, Zhongrui Yan

    Roles Conceptualization, Data curation, Formal analysis, Writing – review & editing

    zhangpeng4544@163.com (PZ); zhongruiy@163.com (ZY)

    Affiliation Department of Neurology, Jining No.1 People’s Hospital, Jining, Shandong, China

Abstract

Objective

The association between cerebral microbleeds (CMBs), an indicator of microvascular damage on MRI, and incident dementia (ID) remains inconclusive. We aim to investigate the interplay of CMB presence, number, and location with ID in a large community-based elderly cohort.

Methods

The study included 1532 dementia-free participants (aged ≥ 65 years) derived from baseline examinations (2012–2013) of the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS). The ID cases were diagnosed at visits 6 (2016–2017), 7 (2018–2019), and 8 (2019–2020). Cox proportional-hazards models were deployed to assess the association of CMB presence, number, and location with ID.

Results

Over a nine-year follow-up (median = 8.1 years), 390 participants developed ID. Microbleed (MB) presence was related to an increased ID risk (HR = 1.24, 95% CI = 1.02–1.51). A stronger association was observed in those with mixed (lobar+subcortical) MBs (HR = 1.60, 95% CI = 1.10–2.30). Compared to participants without MBs, those with ≥ 2 CMBs in any MBs, any lobar MBs, and any subcortical MBs were associated with 57%, 174%, and 74% higher ID risks. Furthermore, those with a pattern of only lobar MBs or superficial siderosis had the highest ID risk (HR = 1.80, 95% CI = 1.26–2.65).

Interpretation

In this large community-based elderly cohort, we identified that the presence of MBs or a high MB count (i.e., ≥ 2), with some specificity for location, was independently related to an increased ID risk over a nine-year follow-up.

1. Introduction

Studies of cerebral small vessel disease (CSVD) implication in dementia have largely focused on brain imaging signs, including lacunes, brain atrophy, and white matter hyperintensities (WMHs) [14]. Till now, the evidence for the role of cerebral microbleeds (CMBs) in incident dementia (ID) development is limited and controversial. A meta-analysis of five longitudinal studies did not reach statistical significance for the associations between CMBs and ID risk (HR = 1.41, 95% CI 0.90–2.21) [5]. However, two additional population-based studies have provided further insight regarding the relationship between CMBs and dementia risk. These studies all demonstrated an elevated risk of dementia ranging from 70% to 90% for individuals with microbleeds (MBs) [6,7]. Furthermore, a longitudinal study indicated that individuals with ≥ 3 CMBs showed a more rapid deterioration in processing speed, memory, and global cognitive function [8]. Collectively, the evidence remains inconclusive regarding the role of CMBs in ID pathogenesis, as the majority of studies to date have been constrained by small sample sizes and limited statistical power [913] or short follow-up periods [6,8,12,13]. It is imperative to address the latter, as MB progresses slowly and participants manifest minimal to no cognitive change over shorter follow-up periods. Furthermore, to our knowledge, limited research has delved into the link between CMBs and ID, specifically in elderly community-dwelling participants. Consequently, there is a compelling need to conduct a comprehensive investigation into the relationships between CMBs and ID risk in a large sample size of community-dwelling older adults.

Depending on their locations, CMBs play roles in both neurodegenerative-related and cerebrovascular-specific pathology in dementia development [7]. Lobar MBs are more likely to be associated with cerebral amyloid angiopathy (CAA), a condition regarded as neurodegenerative-related pathology. Subcortical MBs, especially in deep gray and white matter, tend to be linked with hypertensive vasculopathy and, thus, are considered vascular indicators [14]. Consequently, MBs may offer an intriguing link between neurodegenerative and cerebrovascular pathological mechanisms in the development of dementia. However, it is inaccurate to distinguish the type of brain tissue lesion merely on the basis of the anatomical location of CMBs. For instance, in the case of strictly lobar MBs in elderly individuals, there is strong diagnostic precision for CAA [15], but other pathologies can occur [16,17]. Superficial siderosis (SS), an imaging marker of small vessel disease, is characterized by hemosiderin deposition in or overlying the superficial cortex [18] and, when evaluated in combination with strictly lobar MBs, provides better diagnostic accuracy for CAA [19]. Likewise, individuals who combined subcortical MBs or mixed MBs with superficial siderosis are more likely to be associated with hypertensive vasculopathy [19]. Therefore, we hypothesized that the combination of CMBs and SS may be an optimal means for identifying participants at a high risk of dementia.

Using the Atherosclerosis Risk in Communities Study (ARIC) data, the present study aims to investigate whether the presence, number, and location of CMBs are associated with an escalated ID risk in community-dwelling older adults. This prospective cohort, characterized by large samples (≥ 1500 participants) and long-term follow-up (≥ nine years), can address limitations persisting in prior approaches. Additionally, we further explored the mixed contribution of CMBs and SS in the relationship with ID.

2. Method

2.1. Study population

The ARIC is a large community-based prospective cohort with 15,792 participants (45–64 years) recruited between 1986 and 1990 from four United States communities [20]. The ARIC Neurocognitive Study (ARIC-NCS) was conducted as part of the ARIC visit 5, which is regarded as the baseline visit for our study. A total of 1980 participants (aged 66–90 years) who underwent brain MRI and neurocognitive testing were selected for baseline analysis [21]. Follow-up neurocognitive tests were conducted at visits 6 (2016–2017), 7 (2018–2019), and 8 (2019–2020). S1 Fig presents further study details. In total, 1,532 subjects were eligible for the final analyses. All participants signed informed consent, and the study was authorized by the Institutional Review Boards at each study center.

2.2. Brain MRI and microbleed quantification

As previously delineated, structural brain images were obtained at each field center using 3-Tesla scanners [22]. CMBs were defined as hypointense homogenous lesions (generally 2–5 mm or sometimes 10 mm in diameter) using a T2*GRE sequence [18]. Depending on the anatomical location, CMBs were categorized as lobar (at lobar or cortical gray; including frontal, occipital, temporal, parietal, and insula) and subcortical (at subcortical or periventricular; including thalamus, basal ganglia, corpus callosum, internal capsule, and deep and periventricular white matter) MBs [2123]. SS was identified as hypointensity on the T2*GRE sequence that followed the contour of the gyrus or sulci [18]. WMH volumes were calculated by a semiautomated segmentation algorithm [14]. Lacunes were assessed visually on fluid-attenuated inversion recovery/T1-weighted MRI scans [23]. Using the Freesurfer atlas, we additionally calculated the volume of the hippocampus and other Alzheimer’s disease signature regions (cuneus, precuneus, entorhinal, inferior parietal lobule, and parahippocampal) [14].

2.3. Incident Dementia

Dementia cases of participants who participated in the in-person follow-ups (at visit 5 NCS, 6, 7, and 8) were adjudicated by expert committee review using comprehensive neurocognitive test batteries [2426]. For participants who died or declined in-person follow-up waves, ID was identified from dementia surveillance using hospitalization and death certificate codes and annual follow-up telephone interviews [2325,27]. The onset date of ID was determined by identifying the earliest occurrence among the following events: the first follow-up visit when dementia was identified, the first telephone interview with the participant or proxy with the diagnosis of dementia, and the first hospital discharge or death certificate codes for dementia [23].

2.4. Covariates

In the present study, we incorporated potential confounders that had previously been considered to be associated with dementia, including sociodemographic, lifestyle, and genetic factors [28]. Sociodemographic information obtained at the study baseline included self-reported sex (male and female), race (white and black), and educational level (i.e., < high school, high school, ≥ college). As MBs were evaluated at visit 5, other covariates were defined at this visit unless otherwise indicated: age, body mass index (BMI; weight/height2), apolipoprotein E (APOE) ε4 genotype (ε4 carriers versus noncarriers), smoking status (ever vesus never), low-/high-density lipoprotein (LDL)/(HDL), diabetes (defined as hemoglobin A1c ≥ 6.5%, fasting glucose ≥ 126 mg/dL, non-fasting glucose ≥ 200 mg/dL, physician-confirmed self-reported diagnosis, or usage of insulin or diabetes drugs), hypertension (defined as using hypertension medication, or SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg), and depressive symptoms (evaluated by the 11-item Center for Epidemiologic Studies Depression Scale with a threshold score of 9 or higher).

2.5. Statistical analysis

The participants’ characteristics were compared across three MB categories (no MBs, 1 MB, and ≥ 2 MBs) using the chi-square test for categorical variables and the one-way ANOVA or the Kruskal-Wallis test for continuous variables. Descriptive statistics were also employed to compare baseline characteristics between subjects with and without ID.

The evaluation of CMB patterns was conducted by initially analyzing each location independently (lobar: yes/no; subcortical: yes/no). Subsequently, a variable was developed to represent the overall pattern based on MB location and distribution. This variable included the following categories: none (used as the reference), only lobar MBs, only subcortical MBs, and mixed (lobar+subcortical) MBs [19]. We further evaluated these categories, incorporating SS alongside lobar MBs as a potential indicator of CAA (considering no MBs or superficial siderosis as the reference, versus only lobar MBs or superficial siderosis, only subcortical MBs and mixed (subcortical MBs+either lobar MBs or SS)) [19]. Cumulative incidences of ID were plotted using Kaplan-Meier curves for the different MB patterns. Statistical differences were assessed through log-rank tests. Cox-proportional hazard models were deployed to investigate the effect of the presence (no; yes), number (0; 1; ≥ 2), and pattern of MBs evaluated in association with ID. We constructed three models for the Cox-proportional hazards analyses. Model 1 was adjusted for age, sex, race, BMI, depressive symptoms, APOE ε4 allele, and educational level. Model 2 was additionally adjusted for ever smoking, HDL-C, LDL-C, hypertension, and diabetes. Model 3 was adjusted for Model 2 plus hippocampal volume, an imaging marker for neurodegenerative processes.

Furthermore, we employed multiplicative interaction analyses to examine the potential modification effects of covariates and MBs. When statistical interactions were identified, additional stratified analyses were conducted to assess the direction and magnitude of the interaction.

Three sets of sensitivity analyses were also employed to ascertain the findings’ robustness. First, we excluded participants with mild cognitive impairment to eliminate the potential effects of reverse causation. Second, we excluded participants whose ID occurred within two years of follow-up. Third, in order to test the associations independent of genetic influences, we reanalyzed the correlation between MBs and ID by excluding participants with APOE ε4 status.

Additionally, the improvement in the presence of ID risk reclassification and discrimination with CMBs was evaluated by computing integrated discrimination index (IDI) and net reclassification improvement (NRI). The IDI is employed to quantify the increase in the separation of events and nonevents, while the NRI is used to quantify the amount of correct reclassification introduced by using a model with added variables. The covariates involved in the baseline model are the same covariates used in Cox-proportional hazard analyses. When the NRI or IDI > 0 [29,30], it indicates that the new model shows a performance improvement compared to the old models. In addition, the predictive power of the new models is shown to be better when the calculated NRI or IDI values are larger.

All statistical analyses were performed utilizing R (v4.2.0) and EmpowerStats (X&Y Solutions, Inc., Boston, MA). Results with p < 0.05 were deemed statistically significant.

2.6. Ethics approval and consent to participate

The study followed the Declaration of Helsinki and was authorized by the Ethics Committee of Jining No.1 People’s Hospital (2024-IIT-069).

3. Results

3.1. Participants characteristics

Of the 1532 participants, the mean age was 76.1 years, 40.3% were male, and 25.9% were black. During the 9-year follow-up (median, 8.1 years; interquartile range, 6.8–8.7), 390 participants were diagnosed with ID. Compared to dementia-free individuals, those with dementia were more likely to be older, obese, less educated, show worse cognitive performance, and have worse depressive symptoms. Furthermore, individuals who developed dementia have a higher prevalence of the APOE ε4 allele and a higher burden of MRI markers (including higher volume of the hippocampus, nonhippocampal AD signature region, and white matter hyperintensities and higher prevalence of lacunar infarcts and presence of MBs) (S1 Table). Additionally, compared to individuals with no MBs, those with MBs were slightly older, more likely to be male, had an escalated burden of white matter hyperintensities, and had higher lacunar infarct prevalence (S2 Table).

3.2. Association between the presence, number, and location of MBs with ID

Cumulative incidence curves (Fig 1) showed that, compared to participants with no MBs, those with any MBs, any lobar MBs, any subcortical MBs, only lobar MBs, and mixed (lobar+subcortical) MBs had a higher risk for ID. After adjustment for age, sex, race, BMI, depressive symptoms, APOE ε4 allele, and educational level, any MBs (HR = 1.24, 95% CI 1.02–1.51), any lobar MBs (HR = 1.55, 95% CI 1.18–2.03) and mixed (lobar+subcortical) MBs (HR = 1.70, 95% CI 1.20–2.40) were significantly connected with ID (Fig 2, Model 1). When additionally adjusting for ever smoking, HDL, LDL, hypertension, and diabetes at baseline (Fig 2, Model 2), the above three MBs patterns were still independently associated with a higher risk of ID (HR = 1.26, 95% CI 1.04–1.53; HR = 1.59, 95% CI 1.21–2.11; HR = 1.70, 95% CI 1.20–2.40). After finally adjusting for hippocampal volume (Fig 2, Model 3), a significant association was still recognized for the presence of mixed (lobar+subcortical) MBs (HR = 1.60, 95% CI 1.10–2.30), stronger than for the presence of any MBs (HR = 1.24, 95% CI 1.02–1.51) and presence of any lobar MBs (HR = 1.54, 95% CI 1.16–2.03).

thumbnail
Fig 1. Cumulative risk of incident dementia, by microbleed patterns.

https://doi.org/10.1371/journal.pone.0340361.g001

thumbnail
Fig 2. Cerebral microbleed patterns and the risk of incident dementia.

The figure summarizes Cox proportional hazards analyses for studying associations between cerebral microbleed patterns and incident dementia. Model 1 was adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, and educational level. Model 2 was additionally adjusted for ever smoking, HDL-C, LDL-C, hypertension, and diabetes. Model 3 was adjusted for Model 2 plus hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.g002

In accordance, compared to participants with no MBs, those with ≥ 2 MBs had a significant association with ID (HR = 1.56, 95% CI 1.19–2.04). There were consistent association patterns for individuals with ≥ 2 any lobar or subcortical MBs (HR = 2.74, 95% CI 1.81–4.14; HR = 1.74, 95% CI 1.29–2.37). However, only lobar or subcortical MBs showed no significant associations (HR = 1.84, 95% CI 0.68–4.98; HR = 1.42, 95% CI 0.92–2.19, Fig 3).

thumbnail
Fig 3. Associations between the location and number of cerebral microbleeds and incident dementia.

The figure summarizes Cox proportional hazards analyses for studying associations between the location and number of cerebral microbleeds with incident dementia. Model 1 was adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, and educational level. Model 2 was additionally adjusted for ever smoking, HDL-C, LDL-C, hypertension, and diabetes. Model 3 was adjusted for Model 2 plus hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.g003

In the total population, we found a statistically significant interaction of race and educational level with any MBs on ID (p for interaction = 0.03 and 0.01, respectively). Further stratification analysis indicated that the associations of any MBs with ID were stronger in black and low levels of education than in white and high levels of education (Fig 4).

thumbnail
Fig 4. Forest plot of the associations of cerebral microbleeds with incident dementia by racea and educational levelb.

aHazard ratio (95% confidence interval) was adjusted for age, sex, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume. bHazard ratio (95% confidence interval) was adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.g004

3.3. Associations of MB location pattern combined SS with ID

Additionally, we combined MB location with SS, a CAA-type marker, to evaluate the mixed contribution to the development of ID. A similar association was observed for the mixed pattern (subcortical MBs+either lobar MBs or SS) of CMBs (HR = 1.44, 95% CI 1.02–2.05), independent of common dementia risk factors (Table 1). Furthermore, compared to participants with no MBs or SS, those with a pattern of only lobar MBs or SS displayed the highest ID risk (HR = 1.80, 95% CI 1.26–2.65). Similar to the previous result, no significant association was observed between only subcortical MBs and ID (HR = 1.11, 95% CI 0.87–1.42). Cumulative incidence curves showcased that, compared to individuals with no MBs or SS, those with only lobar MBs or SS and mixed (subcortical MBs+either lobar MBs or SS) pattern of CMBs had a higher risk for ID (Fig 1).

thumbnail
Table 1. Associations between microbleed patterns, superficial siderosis, and incident dementia.

https://doi.org/10.1371/journal.pone.0340361.t001

3.4. Sensitivity analysis

First, we reanalyzed our data after excluding participants diagnosed with mild cognitive impairment at the baseline. In comparison with no MBs, the presence of any MBs, any lobar MBs, and mixed (subcortical+lobar) MBs had a higher risk of ID, whereas only lobar MBs and only subcortical MBs remained non-significant. Second, the primary findings did not change significantly after excluding participants whose dementia was diagnosed in the first two years of follow-up. Third, when the subjects were limited to negative APOE ε4 carrier status, the effects of the above pattern of MBs on the risk of dementia were also sustained (S3 Table). Additionally, in the sensitivity analysis, similar associations were observed when we combined MB location with superficial siderosis (S4 Table).

3.5. Improvement in the prediction model for ID risks by the addition of the MB patterns

We compared the performance of different models for predicting the ID risks in participants of the ARIC study (S5 Table). The addition of the presence of MBs to the basic model improved the performance validated by IDI. Surprisingly, the NRIs of the MB patterns (any MBs, any lobar MBs, any subcortical MBs, only lobar MBs, only subcortical MBs, and mixed MBs) for estimating ID risks were 17.00% (95% CI = 8.40–24.40), 16.20% (7.10–25.40), 17.20% (8.30–24.30), 17.80% (8.60–26.50), 17.20% (9.70–26.00), and 15.60% (6.70–23.50), respectively. To sum up, the addition of the MB patterns to the basic model with traditional risk factors improved the predictive ability for ID risks, as validated by the IDI and NRI (all p < 0.001).

4. Discussion

In this large community-based elderly cohort, we identified that the presence of MBs or a high MB count (i.e., ≥ 2), with some specificity for location, was independently associated with an increased risk of ID over a 9-year follow-up. In addition, a stronger association was observed in participants with a pattern of only lobar MBs or superficial siderosis for dementia. Collectively, our findings provide amplified evidence that MBs function as an independent contributor to ID risk and highlight the need to consider superficial siderosis alongside MBs.

Our results align with other studies [6,7], which indicated that the presence of MBs was related to a statistically significant increased ID risk. A population-based study of over three thousand participants indicated that the presence of MBs was related to a twofold increased risk of ID over a mean follow-up of 4.8 years [6], while another study reported a 74% elevated ID risk over 6 years [7]. Conversely, other studies have suggested no link between MBs and the risk of dementia [12,13]. These inconsistent results could stem from reverse causation bias due to short follow-up periods in previous studies (i.e., < 5 years). The prolonged duration of the follow-up period, which extends up to 9 years, serves to mitigate the potential for reverse causation bias in our study. Moreover, the majority of previous studies did not adjust for hippocampal volume, a significant neurodegenerative confounder in ID [6,813]. Consequently, it is possible that ongoing neurodegeneration accounted for the onset of dementia shortly after the initial assessment. Therefore, our present study augmented the clinical significance of MBs. Furthermore, our findings demonstrated that MB severity (the number of MBs) at baseline was also linked to an elevated risk of ID. Previously, several longitudinal studies have indicated relationships between multiple MBs and cognitive decline [6,31,32]. However, these studies either had a lower mean age or did not evaluate this association separately for different MB locations. The present findings, thus, contribute substantially to our understanding of the cognitive consequences of MB severity in community-dwelling elderly individuals.

It was determined that the relationships with ID exhibited variation following the spatial location of CMBs. In our present study, a statistically marginal association was detected between MBs in strictly lobar regions, suggestive of CAA, and the risk of ID. However, the result became significant when we linked strictly lobar MBs and superficial siderosis together to evaluate the risk of ID, which was consistent with a recently published study that the lobar-only pattern of MBs or superficial siderosis was most significantly correlated with cerebral amyloid-beta deposition [19]. Furthermore, no elevated risk was observed for any subcortical MB patterns in conjunction with ID, indicating that merely hypertensive vasculopathy has a relatively weaker effect on the development of ID. Notably, we found that mixed (lobar+subcortical) MBs were most strongly correlated with the risk of dementia. Our results emphasize the role of amyloid pathologic features and cerebrovascular-specific pathology in the pathogenesis of dementia. However, the mechanism of amyloid pathologic features interacting with cerebrovascular-specific pathology to trigger dementia remains unclear. Two relatively well-studied mechanisms are discussed: First, vascular cell APOE4 leads to tight junction impairments, increased pericyte migration and degeneration, decreased synaptic plasticity, reduced blood flow, and increased Aβ deposition in the form of CAA [33]. Additionally, cerebrovascular deposition of Aβ has been demonstrated to impair the reactivity of microvasculature, leading to subsequent microstructural changes of cerebrovasculature and the development of hemorrhagic brain lesions [3438]. Second, hypertension-associated CSVD also leads to dysfunctions in amyloid clearance and further enhances the accumulation of amyloid deposition in vessel walls [3941].

Interestingly, we detected potential interactions of any MBs with race and educational level on ID such that the relationships of any MBs with the development of dementia were stronger in black and low levels of education than in white and high levels of education. In keeping with this finding, previous research has reported that black individuals have limited access to education, which may lead to socioeconomic disparities and earlier differences in cognitive reserve. Furthermore, their limited access to healthcare services may contribute to an escalated burden of vascular risk factors [42,43]. Therefore, the reasons above might partially account for the race and educational level-specific differences in the correlation of MBs with the risk of dementia.

The advantages of our study are the longitudinal community-based design with a large sample size, the long follow-up times, the comprehensive cognitive assessments, and the standardized dementia detection system. However, several limitations exist in our study. First, employing the T2*GRE sequence, rather than the susceptibility-weighted imaging sequence, may lead to underestimation of CMB burden, particularly in lobar regions. Thus, this could influence both the classification of CMB regions and the strength of associations with ID risk. Second, given the scarcity of data regarding dementia diagnoses obtained through approaches other than expert adjudication (i.e., annual follow-up telephone interviews, informant interviews, and hospitalization and death certificate codes), we were unable to identify specific dementia subtypes and could not separately investigate the distinct relationships between MBs and Alzheimer’s disease or vascular dementia. Nevertheless, this solely restricts the stratified analyses since Alzheimer’s disease, whether occurring independently or alongside other neurological conditions, remains the predominant etiology for late-life dementia. Third, we excluded participants diagnosed with mild cognitive impairment at baseline. However, the primary findings did not change significantly in our sensitivity analyses, indicating that this may be less likely to introduce bias in the interpretation of the current results. Fourth, although we considered numerous confounders, residual confounding, such as chronic kidney disease, inflammatory markers, and lifestyle indices, may still have interfered with our findings. Despite these limitations, our study had some strengths, including the large number of participants and the high rate of follow-up. Fifth, while our findings indicated that the presence of MBs independently contributes to future dementia, we could not recommend specific interventions to reduce the risk of cognitive decline. A two-sample, two-step Mendelian Randomization study showed that the Sodium-glucose cotransporter 2 could reduce the risk of MBs but remains uncertain in reducing cognitive impairment [44,45].

5. Conclusions

In conclusion, both MB presence and MB severity at baseline were independently related to the long-term risk of ID in this large community-based elderly cohort. The strength of the association was found to be most significant among participants with mixed (lobar+subcortical) MBs, indicating the combined effect of CAA and hypertensive vasculopathy in dementia development. Furthermore, both lobar MB and superficial siderosis should be considered to understand the neurodegenerative contributions to cognitive decline. Collectively, our results provide amplified evidence and indicate that the presence of MBs or a high MB count, with some specificity for location, may be imperative for estimating ID risks.

Supporting information

S1 Table. Baseline characteristics of participants with and without incident dementia.

Abbreviations: APOE = apolipoprotein E; HDL-C = high-density lipoprotein cholesterol; LDL-C = high-density lipoprotein cholesterol; MMSE = Mini Mental State Examination; WMH = white matter hyperintensity.

https://doi.org/10.1371/journal.pone.0340361.s001

(DOCX)

S2 Table. Characteristics of participants in 2011–2013 (Visit 5) by presence and number of microbleeds on brain MRI.

Abbreviations: APOE = apolipoprotein E; HDL-C = high-density lipoprotein cholesterol; LDL-C = low-density lipoprotein cholesterol; MMSE = Mini Mental State Examination; WMH = white matter hyperintensity.

https://doi.org/10.1371/journal.pone.0340361.s002

(DOCX)

S3 Table. Sensitivity analysis on the association between microbleed patterns and incident dementia.

Abbreviations: APOE = apolipoprotein E; MCI = mild cognitive impairment. a Hazard ratio of incident dementia in the population excluding those diagnosed with MCI, adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume. b Hazard ratio of incident dementia in the population excluding those whose dementia was ascertained in the first two years, adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume. c Hazard ratio of incident dementia in the population excluding participants with APOE ε4 status, adjusted for age, sex, race, body mass index, depressive symptoms, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.s003

(DOCX)

S4 Table. Sensitivity analysis on the association between microbleed patterns or superficial siderosis and incident dementia.

Abbreviations: APOE = apolipoprotein E; MCI = mild cognitive impairment. a Hazard ratio of incident dementia in the population excluding those diagnosed with MCI, adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume. b Hazard ratio of incident dementia in the population excluding those whose dementia was ascertained in the first two years, adjusted for age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume. c Hazard ratio of incident dementia in the population excluding participants with APOE ε4 status, adjusted for age, sex, race, body mass index, depressive symptoms, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.s004

(DOCX)

S5 Table. The net reclassification index and integrated discrimination improvement estimate of incident dementia.

Abbreviations: CI = confidence interval; IDI = integrated discrimination improvement; LDL-C = low-density lipoprotein cholesterol; NRI = net reclassification index; Ref = reference. Basic model: Cox proportional-hazards model included age, sex, race, body mass index, depressive symptoms, APOE ε4 allele, educational level, ever smoking, HDL-C, LDL-C, hypertension, diabetes, and hippocampal volume.

https://doi.org/10.1371/journal.pone.0340361.s005

(DOCX)

S1 Fig. Flow diagram of study participants.

https://doi.org/10.1371/journal.pone.0340361.s006

(DOCX)

Acknowledgments

The authors extend their gratitude to Home for Researchers (www.home-for-researchers.com) for providing professional language editing services and the ARIC study staff for their contributions.

References

  1. 1. Debette S, Schilling S, Duperron M-G, Larsson SC, Markus HS. Clinical significance of magnetic resonance imaging markers of vascular brain injury: A systematic review and meta-analysis. JAMA Neurol. 2019;76(1):81–94. pmid:30422209
  2. 2. Wardlaw JM, Smith C, Dichgans M. Small vessel disease: Mechanisms and clinical implications. Lancet Neurol. 2019;18(7):684–96. pmid:31097385
  3. 3. Chapleau M, La Joie R, Yong K, Agosta F, Allen IE, Apostolova L, et al. Demographic, clinical, biomarker, and neuropathological correlates of posterior cortical atrophy: An international cohort study and individual participant data meta-analysis. Lancet Neurol. 2024;23(2):168–77. pmid:38267189
  4. 4. Filler J, Georgakis MK, Dichgans M. Risk factors for cognitive impairment and dementia after stroke: A systematic review and meta-analysis. Lancet Healthy Longev. 2024;5(1):e31–44. pmid:38101426
  5. 5. Charidimou A, Shams S, Romero JR, Ding J, Veltkamp R, Horstmann S, et al. Clinical significance of cerebral microbleeds on MRI: A comprehensive meta-analysis of risk of intracerebral hemorrhage, ischemic stroke, mortality, and dementia in cohort studies (v1). Int J Stroke. 2018;13(5):454–68. pmid:29338604
  6. 6. Akoudad S, Wolters FJ, Viswanathan A, de Bruijn RF, van der Lugt A, Hofman A, et al. Association of Cerebral Microbleeds With Cognitive Decline and Dementia. JAMA Neurol. 2016;73(8):934–43. pmid:27271785
  7. 7. Romero JR, Beiser A, Himali JJ, Shoamanesh A, DeCarli C, Seshadri S. Cerebral microbleeds and risk of incident dementia: the Framingham Heart Study. Neurobiol Aging. 2017;54:94–9. pmid:28347929
  8. 8. Ding J, Sigurðsson S, Jónsson PV, Eiriksdottir G, Meirelles O, Kjartansson O, et al. Space and location of cerebral microbleeds, cognitive decline, and dementia in the community. Neurology. 2017;88(22):2089–97. pmid:28468844
  9. 9. Miwa K, Tanaka M, Okazaki S, Yagita Y, Sakaguchi M, Mochizuki H, et al. Multiple or mixed cerebral microbleeds and dementia in patients with vascular risk factors. Neurology. 2014;83(7):646–53. pmid:25015364
  10. 10. van Uden IWM, van der Holst HM, Tuladhar AM, van Norden AGW, de Laat KF, Rutten-Jacobs LCA, et al. White Matter and Hippocampal Volume Predict the Risk of Dementia in Patients with Cerebral Small Vessel Disease: The RUN DMC Study. J Alzheimer’s Disease. 2015;49(3):863–73.
  11. 11. Miwa K, Tanaka M, Okazaki S, Yagita Y, Sakaguchi M, Mochizuki H, et al. Increased total homocysteine levels predict the risk of incident dementia independent of cerebral small-vessel diseases and vascular risk factors. J Alzheimers Dis. 2016;49(2):503–13. pmid:26484913
  12. 12. Benedictus MR, van Harten AC, Leeuwis AE, Koene T, Scheltens P, Barkhof F, et al. White matter hyperintensities relate to clinical progression in subjective cognitive decline. Stroke. 2015;46(9):2661–4. pmid:26173729
  13. 13. Staekenborg SS, Koedam ELGE, Henneman WJP, Stokman P, Barkhof F, Scheltens P, et al. Progression of mild cognitive impairment to dementia: Contribution of cerebrovascular disease compared with medial temporal lobe atrophy. Stroke. 2009;40(4):1269–74. pmid:19228848
  14. 14. Graff-Radford J, Simino J, Kantarci K, Mosley TH, Griswold ME, Windham BG, et al. Neuroimaging correlates of cerebral microbleeds: The ARIC study (atherosclerosis risk in communities). Stroke. 2017;48(11):2964–72. pmid:29018129
  15. 15. Charidimou A, Boulouis G, Frosch MP, Baron J-C, Pasi M, Albucher JF, et al. The Boston criteria version 2.0 for cerebral amyloid angiopathy: A multicentre, retrospective, MRI-neuropathology diagnostic accuracy study. Lancet Neurol. 2022;21(8):714–25. pmid:35841910
  16. 16. van Veluw SJ, Biessels GJ, Klijn CJM, Rozemuller AJM. Heterogeneous histopathology of cortical microbleeds in cerebral amyloid angiopathy. Neurology. 2016;86(9):867–71. pmid:26843561
  17. 17. Jolink WMT, van Veluw SJ, Zwanenburg JJM, Rozemuller AJM, van Hecke W, Frosch MP, et al. Histopathology of cerebral microinfarcts and microbleeds in spontaneous intracerebral hemorrhage. Transl Stroke Res. 2023;14(2):174–84. pmid:35384634
  18. 18. Duering M, Biessels GJ, Brodtmann A, Chen C, Cordonnier C, de Leeuw F-E, et al. Neuroimaging standards for research into small vessel disease-advances since 2013. Lancet Neurol. 2023;22(7):602–18. pmid:37236211
  19. 19. Okine DN, Knopman DS, Mosley TH, Wong DF, Johansen MC, Walker KA, et al. Cerebral Microbleed patterns and cortical Amyloid-β: The ARIC-PET study. Stroke. 2023;54(10):2613–20. pmid:37638398
  20. 20. Wright JD, Folsom AR, Coresh J, Sharrett AR, Couper D, Wagenknecht LE, et al. The ARIC (atherosclerosis risk in communities) study: JACC focus seminar 3/8. J Am Coll Cardiol. 2021;77(23):2939–59. pmid:34112321
  21. 21. Eswaran S, Knopman DS, Koton S, Kucharska-Newton AM, Liu AC, Liu C, et al. Psychosocial health and the association between cerebral small vessel disease markers with dementia: The ARIC study. Stroke. 2024;55(10):2449–58. pmid:39193713
  22. 22. Schneider ALC, Selvin E, Sharrett AR, Griswold M, Coresh J, Jack CR, et al. Diabetes, prediabetes, and brain volumes and subclinical cerebrovascular disease on MRI: The Atherosclerosis risk in communities neurocognitive study (ARIC-NCS). Diabetes Care. 2017;40(11):1514–21. pmid:28916531
  23. 23. Wu A, Sharrett AR, Gottesman RF, Power MC, Mosley TH, Jack CR, et al. Association of brain magnetic resonance imaging signs with cognitive outcomes in persons with nonimpaired cognition and mild cognitive impairment. JAMA Netw Open. 2019;2(5):e193359. pmid:31074810
  24. 24. Gottesman RF, Albert MS, Alonso A, Coker LH, Coresh J, Davis SM, et al. Associations between midlife vascular risk factors and 25-year incident dementia in the atherosclerosis risk in communities (ARIC) cohort. JAMA Neurol. 2017;74(10):1246–54. pmid:28783817
  25. 25. Zhao D, Guallar E, Qiao Y, Knopman DS, Palatino M, Gottesman RF, et al. Intracranial Atherosclerotic Disease and Incident Dementia: The ARIC Study (Atherosclerosis Risk in Communities). Circulation. 2024;150(11):838–47. pmid:39087353
  26. 26. Kamath V, Senjem ML, Spychalla AJ, Chen H, Palta P, Mosley TH, et al. The neuroanatomic correlates of olfactory identification impairment in healthy older adults and in persons with mild cognitive impairment. J Alzheimers Dis. 2022;89(1):233–45. pmid:35871337
  27. 27. Tin A, Bressler J, Simino J, Sullivan KJ, Mei H, Windham BG, et al. Genetic risk, midlife life’s simple 7, and incident dementia in the atherosclerosis risk in communities study. Neurology. 2022;99(2):e154–63. pmid:35613930
  28. 28. Livingston G, Huntley J, Liu KY, Costafreda SG, Selbæk G, Alladi S, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet. 2024;404(10452):572–628. pmid:39096926
  29. 29. Thomas LE, O’Brien EC, Piccini JP, D’Agostino RB, Pencina MJ. Application of net reclassification index to non-nested and point-based risk prediction models: A review. Eur Heart J. 2019;40(23):1880–7. pmid:29955849
  30. 30. Moons KGM, de Groot JAH, Linnet K, Reitsma JB, Bossuyt PMM. Quantifying the added value of a diagnostic test or marker. Clin Chem. 2012;58(10):1408–17. pmid:22952348
  31. 31. Liem MK, Lesnik Oberstein SAJ, Haan J, van der Neut IL, Ferrari MD, van Buchem MA, et al. MRI correlates of cognitive decline in CADASIL: A 7-year follow-up study. Neurology. 2009;72(2):143–8. pmid:19139365
  32. 32. Meier IB, Gu Y, Guzaman VA, Wiegman AF, Schupf N, Manly JJ, et al. Lobar microbleeds are associated with a decline in executive functioning in older adults. Cerebrovasc Dis. 2014;38(5):377–83. pmid:25427958
  33. 33. Blumenfeld J, Yip O, Kim MJ, Huang Y. Cell type-specific roles of APOE4 in Alzheimer disease. Nat Rev Neurosci. 2024;25(2):91–110. pmid:38191720
  34. 34. Chen S, Guo D, Zhu Y, Xiao S, Xie J, Zhang Z, et al. Amyloid β oligomer induces cerebral vasculopathy via pericyte-mediated endothelial dysfunction. Alzheimers Res Ther. 2024;16(1):56. pmid:38475929
  35. 35. Dewenter A, Jacob MA, Cai M, Gesierich B, Hager P, Kopczak A, et al. Disentangling the effects of Alzheimer’s and small vessel disease on white matter fibre tracts. Brain. 2023;146(2):678–89. pmid:35859352
  36. 36. Koemans EA, Chhatwal JP, van Veluw SJ, van Etten ES, van Osch MJP, van Walderveen MAA, et al. Progression of cerebral amyloid angiopathy: A pathophysiological framework. Lancet Neurol. 2023;22(7):632–42. pmid:37236210
  37. 37. Coomans EM, van Westen D, Binette AP, Strandberg O, Spotorno N, Serrano GE, et al. Interactions between vascular burden and amyloid-β pathology on trajectories of tau accumulation. Brain. 2024;147(3):949–60. pmid:37721482
  38. 38. Lorenzini L, Maranzano A, Ingala S, Collij LE, Tranfa M, Blennow K, et al. Association of vascular risk factors and cerebrovascular pathology with alzheimer disease pathologic changes in individuals without dementia. Neurology. 2024;103(7):e209801. pmid:39288341
  39. 39. Hainsworth AH, Markus HS, Schneider JA. Cerebral small vessel disease, hypertension, and vascular contributions to cognitive impairment and dementia. Hypertension. 2024;81(1):75–86. pmid:38044814
  40. 40. van Arendonk J, Neitzel J, Steketee RME, van Assema DME, Vrooman HA, Segbers M, et al. Diabetes and hypertension are related to amyloid-beta burden in the population-based Rotterdam Study. Brain. 2023;146(1):337–48. pmid:36374264
  41. 41. Bachmann D, Saake A, Studer S, Buchmann A, Rauen K, Gruber E, et al. Hypertension and cerebral blood flow in the development of Alzheimer’s disease. Alzheimers Dement. 2024;20(11):7729–44. pmid:39254220
  42. 42. Li R, Li R, Xie J, Chen J, Liu S, Pan A, et al. Associations of socioeconomic status and healthy lifestyle with incident early-onset and late-onset dementia: A prospective cohort study. Lancet Healthy Longev. 2023;4(12):e693–702. pmid:38042162
  43. 43. Fang M, Hu J, Weiss J, Knopman DS, Albert M, Windham BG, et al. Lifetime risk and projected burden of dementia. Nat Med. 2025;31(3):772–6. pmid:39806070
  44. 44. Lv Y, Cheng X, Dong Q. SGLT1 and SGLT2 inhibition, circulating metabolites, and cerebral small vessel disease: A mediation Mendelian Randomization study. Cardiovasc Diabetol. 2024;23(1):157. pmid:38715111
  45. 45. Elahi FM, Wang MM, Meschia JF. Cerebral small vessel disease-related dementia: More questions than answers. Stroke. 2023;54(3):648–60. pmid:36848423