Background:
Cerebral small vessel disease (cSVD) is a major cause of stroke and dementia. Previous studies on the prevalence of cSVD are mostly based on single geographically defined cohorts in ...high-income countries. Studies investigating the prevalence of cSVD in low- and middle-income countries (LMICs) are expanding but have not been systematically assessed.
Aim:
This study aims to systematically review the prevalence of cSVD in LMICs.
Results:
Articles were searched from the Ovid MEDLINE and EMBASE databases from 1 January 2000 to 31 March 2022, without language restrictions. Title/abstract screening, full-text review, and data extraction were performed by two to seven independent reviewers. The prevalence of cSVD and study sample size were extracted by pre-defined world regions and health status. The Risk of Bias for Non-randomized Studies tool was used. The protocol was registered on PROSPERO (CRD42022311133). A meta-analysis of proportion was performed to assess the prevalence of different magnetic resonance imaging markers of cSVD, and a meta-regression was performed to investigate associations between cSVD prevalence and type of study, age, and male: female ratio. Of 2743 studies identified, 42 studies spanning 12 global regions were included in the systematic review. Most of the identified studies were from China (n = 23). The median prevalence of moderate-to-severe white matter hyperintensities (WMHs) was 20.5%, 40.5%, and 58.4% in the community, stroke, and dementia groups, respectively. The median prevalence of lacunes was 0.8% and 33.5% in the community and stroke groups. The median prevalence of cerebral microbleeds (CMBs) was 10.7% and 22.4% in the community and stroke groups. The median prevalence of moderate-to-severe perivascular spaces was 25.0% in the community. Meta-regression analyses showed that the weighted median age (51.4 ± 0.0 years old; range: 36.3–80.2) was a significant predictor of the prevalence of moderate-to-severe WMH and lacunes, while the type of study was a significant predictor of the prevalence of CMB. The heterogeneity of studies was high (>95%). Male participants were overrepresented.
Conclusions:
This systematic review and meta-analysis provide data on cSVD prevalence in LMICs and demonstrated the high prevalence of the condition. cSVD research in LMICs is being published at an increasing rate, especially between 2010 and 2022. More data are particularly needed from Sub-Saharan Africa and Central Europe, Eastern Europe, and Central Asia.
Poor social connections (eg, small networks, infrequent interactions, and loneliness) are modifiable risk factors for cognitive decline. Existing meta-analyses are limited by reporting aggregate ...responses, a focus on global cognition, and combining social measures into single constructs. We aimed to investigate the association between social connection markers and the rate of annual change in cognition (ie, global and domain-specific), as well as sex differences, using an individual participant data meta-analysis.
We harmonised data from 13 longitudinal cohort studies of ageing in North America, South America, Europe, Africa, Asia, and Australia. Studies were eligible for inclusion if they had baseline data for social connection markers and at least two waves of cognitive scores. Follow-up periods ranged from 0 years to 15 years across cohorts. We included participants with cognitive data for at least two waves and social connection data for at least one wave. We then identified and excluded people with dementia at baseline. Primary outcomes were annual rates of change in global cognition and cognitive domain scores over time until final follow-up within each cohort study analysed by use of an individual participant data meta-analysis. Linear mixed models within cohorts used baseline social connection markers as predictors of the primary outcomes. Effects were pooled in two stages using random-effects meta-analyses. We assessed the primary outcomes in the main (partially adjusted) and fully adjusted models. Partially adjusted models controlled for age, sex, and education; fully adjusted models additionally controlled for diabetes, hypertension, smoking, cardiovascular risk, and depression.
Of the 40 006 participants in the 13 cohort studies, we excluded 1392 people with dementia at baseline. 38 614 individual participants were included in our analyses. For the main models, being in a relationship or married predicted slower global cognitive decline (b=0·010, 95% CI 0·000–0·019) than did being single or never married; living with others predicted slower global cognitive (b=0·007, 0·002–0·012), memory (b=0·017, 0·006–0·028), and language (b=0·008, 0·000–0·015) decline than did living alone; and weekly interactions with family and friends (b=0·016, 0·006–0·026) and weekly community group engagement (b=0·030, 0·007–0·052) predicted slower memory decline than did no interactions and no engagement. Never feeling lonely predicted slower global cognitive (b=0·047, 95% CI 0·018–0·075) and executive function (b=0·047, 0·017–0·077) decline than did often feeling lonely. Degree of social support, having a confidante, and relationship satisfaction did not predict cognitive decline across global cognition or cognitive domains. Heterogeneity was low (I2=0·00–15·11%) for all but two of the significant findings (association between slower memory decline and living with others I2=58·33% and community group engagement, I2=37·54–72·19%), suggesting robust results across studies.
Good social connections (ie, living with others, weekly community group engagement, interacting weekly with family and friends, and never feeling lonely) are associated with slower cognitive decline.
EU Joint Programme–Neurodegenerative Disease Research grant, funded by the National Health and Medical Research Council Australia, and the US National Institute on Aging of the US National Institutes of Health.
We investigated the effect of poor masticatory ability on cognitive trajectories and dementia risk in older adults. 544 cognitively intact adults aged ≥50 were followed for up to 22 years. Cognitive ...domains (verbal, spatial/fluid, memory, and perceptual speed) were assessed at baseline and follow-ups. Dementia was ascertained according to standard criteria. Masticatory ability was assessed using the Eichner Index and categorized according to the number of posterior occlusal zones: A (all four), B (3-1), and C (none).At baseline, 147 (27.0%) participants were in Eichner category A, 169 (31.1%) in B and 228 (41.9%) in C. After the age of 65, participants in Eichner category B and C showed an accelerated decline in spatial/fluid abilities (β: -0.16, 95% CI: -0.30 to -0.03) and (β: -0.15, 95% CI: -0.28 to -0.02), respectively. Over the follow-up, 52 incident dementia cases were identified. Eichner categories B or C were not associated with an increased risk of dementia, compared to category A (Hazard Ratio HR: 0.83, 95% CI: 0.39 to 1.76 and HR: 0.63, 95% CI: 0.30 to 1.29, respectively).Poor masticatory ability is associated with an accelerated cognitive decline in fluid/spatial abilities, however it was not related to a higher risk of dementia.
The impact of prediabetes and diabetes on different stages of cognitive function during aging remains unclear. This thesis aimed to investigate the impact of prediabetes and of diabetes on cognitive ...aging—from cognitive deficits, through cognitive decline, to dementia—, explore underlying cerebral mechanisms and identify factors that may protect older adults with diabetes from dementia. The four studies in this thesis were based on data from the Swedish National Study on Aging and Care-Kungsholmen (SNAC-K), the SNAC-K brain magnetic resonance imaging (MRI) study, and the Swedish Adoption/Twin Study of Aging (SATSA).Study I. This study used SNAC-K data to identify the cognitive domains sensitive to the detrimental impact of diabetes. In cognitively intact older adults, diabetes was associated with lower performance in perceptual speed (β -1.10; 95% CI -1.98, -0.23), category fluency (β -1.27; 95% CI -2.52, -0.03), and digit span forward (β -0.35; 95% CI -0.54, -0.17). These results suggest that domains of fluid abilities are more sensitive to diabetes than are other cognitive domains.Study II. This study used 23 years of follow-up data from SATSA to investigate the effect of prediabetes and of diabetes on trajectories of cognitive decline in different domains. Diabetes accelerated cognitive decline in perceptual speed (β -0.25; 95% CI -0.44, -0.05) and verbal abilities (β -0.19; 95% CI -0.33, -0.04). Prediabetes was associated with poor memory performance at baseline but with a less steep memory decline over time.Study III. The relationship of prediabetes and of diabetes with global cognitive decline and structural brain changes was assessed with data from SNAC-K and the SNAC-K MRI study. Both accelerated global cognitive decline. Prediabetes was associated with smaller global brain volume, particularly smaller white matter volume at baseline, and diabetes with accumulation of white matter hyperintensities (β 0.56, 95% CI 0.07–1.05) over time.Study IV. The compensatory effect of an active and socially integrated lifestyle on dementia risk in older adults with diabetes was examined with data from SNAC-K. Participants with diabetes and an inactive lifestyle had a higher risk of dementia (HR 6.0, 95% CI 3.0–12.3) than diabetes-free participants with an active lifestyle (high engagement in leisure activities or/and rich social network). In participants with diabetes, an active lifestyle was associated with less of a raised risk (HR 1.9, 95% CI 1.1–3.4).Conclusions. In the initial phase of cognitive deterioration, the domains primarily affected by diabetes may be processing speed, executive function, and attention/primary memory. Over time, having either prediabetes or diabetes accelerates the decline in fluid abilities (i.e., perceptual speed and verbal abilities) and global cognitive decline. At the structural brain level, diabetes is associated with the accumulation of cerebral microvascular lesions, which might start already during prediabetes. Finally, diabetes is associated with an increased risk of dementia. However, an active and socially integrated lifestyle may significantly counteract the detrimental effect of diabetes on brain aging.
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