Gottesman, Rebecca F.

Background and Purpose— The relationships between cerebrovascular lesions visible on imaging and cognition are complex. We explored the possibility that the cerebral cortical volume mediated these relationships. Methods— Total of 1906 nondemented participants (59% women; 25% African–American; mean age, 76.6 years) in the Atherosclerosis Risk in Communities (ARIC) study underwent cognitive assessments, risk factor assessments, and quantitative MRI for white matter hyperintensities (WMH) and infarcts. The Freesurfer imaging analysis pipeline was used to determine regional cerebral volumes. We examined the associations of cognitive domain outcomes with cerebral volumes (hippocampus and separate groups of posterior and frontal cortical regions of interest) and cerebrovascular imaging features (presence of large or small cortical/subcortical infarcts and WMH volume). We performed mediation pathway analyses to assess the hypothesis that hippocampal and cortical volumes mediated the associations between cerebrovascular imaging features and cognition. Results— In unmediated analyses, WMH and infarcts were both associated with worse psychomotor speed/executive function. In mediation analyses, WMH and infarct associations on psychomotor speed/executive function were significantly attenuated, but not abolished, by the inclusion of the posterior cortical regions of interest volume in the models, and the infarcts on psychomotor speed/executive function association were attenuated, but not abolished, by inclusion of the frontal cortical regions of interest volume. Conclusions— Both WMH and infarcts were associated with cortical volume, and both lesions were also associated with cognitive performance, implying shared pathophysiological mechanisms. Although cross-sectional, our findings suggest that WMH and infarcts could be proxies for clinically covert processes that directly damage cortical regions. Microinfarcts are 1 candidate for such a clinically covert process.

Background and purposeSome recent studies in older, largely white populations suggest that vitamin D, measured by 25‐hydroxyvitamin D [25(OH)D], is important for cognition, but such results may be affected by reverse causation. Measuring 25(OH)D in late middle age before poor cognition affects behavior may provide clearer results.MethodsThis was a prospective cohort analysis of 1652 participants (52% white, 48% black) in the Atherosclerosis Risk in Communities (ARIC) Brain MRI Study. 25(OH)D was measured from serum collected in 1993–1995. Cognition was measured by the delayed word recall test (DWRT), the digit symbol substitution test (DSST) and the word fluency test (WFT). Dementia hospitalization was defined by ICD‐9 codes. Adjusted linear, logistic and Cox proportional hazards models were used.ResultsMean age of participants was 62 years and 60% were female. Mean 25(OH)D was higher in whites than blacks (25.5 vs. 17.3 ng/ml, P < 0.001). Lower 25(OH)D was not associated with lower baseline scores or with greater DWRT, DSST or WFT decline over a median of 3 or 10 years of follow‐up (P > 0.05). Over a median of 16.6 years, there were 145 incident hospitalized dementia cases. Although not statistically significant, lower levels of 25(OH)D were suggestive of an association with increased dementia risk [hazard ratio for lowest versus highest race‐specific tertile: whites 1.32 (95% confidence interval 0.69, 2.55); blacks 1.53 (95% confidence interval 0.84, 2.79)].ConclusionsIn contrast to prior studies performed in older white populations, our study of late middle age white and black participants did not find significant associations between lower levels of 25(OH)D with lower cognitive test scores at baseline, change in scores over time or dementia risk.

Background and Purpose— Brain microvascular disease leads to leukoaraiosis and lacunar infarcts and contributes to risk of stroke and cognitive decline. Given a shared pathophysiology, retinal microvascular signs are expected to predict brain microvascular disease progression. We investigated if either leukoaraiosis volume progression measured continuously or combined with incident lacunar infarcts would better demonstrate expected associations with retinal disease than has previously been shown. Methods— Eight hundred thirty participants in the Atherosclerosis Risk in Communities (ARIC) study aged ≥55 years and without previous stroke received an initial brain magnetic resonance imaging, retinal photography, and, 10 years later, a follow up magnetic resonance imaging. We evaluated retinal vascular sign phenotypes as predictors of (1) leukoaraiosis volume increase, and (2) a new score combining leukoaraiosis volume change and incident lacunar infarcts. Hypertension and diabetes mellitus were evaluated as confounders and effect modifiers. Results— Individuals with any retinopathy (3.34 cm 3 ; 95% confidence interval [CI], 0.74–5.96) or with arteriovenous nicking (2.61 cm 3 ; 95% CI, 0.80–4.42) each had greater progression of leukoaraiosis compared with those without these conditions. Any retinopathy (odds ratio [OR], 3.18; 95% CI, 1.71–5.89) or its components—microaneurysms (OR, 3.06; 95% CI, 1.33–7.07) and retinal hemorrhage (OR, 3.02; 95% CI, 1.27–7.20)—as well as arteriovenous nicking (OR, 1.93; 95%, CI 1.24–3.02) and focal arteriolar narrowing (OR, 1.76; 95% CI, 1.19–2.59), were associated with a higher quartile of a novel brain microvascular disease score combining leukoaraiosis progression with incident subclinical lacunes. Conclusions— A novel scoring method revealed associations of retinal signs with leukoaraiosis progression and brain microvascular disease, which have not been shown before.