Metabolic syndrome and localization of white matter hyperintensities in the elderly population

Abstract

Background: Metabolic syndrome (MetS) is defined as a clustering of metabolic disorders: abdominal obesity, dyslipidemia, hypertension, and hyperglycemia. Although specific components of MetS have been associated with white matter hyperintensities (WMH), less is known about the association between MetS as a whole and WMH, especially in normal aging. We aimed to: (1) investigate this association in a cohort of healthy elderly individuals, and (2) examine the relationship between MetS and the regional distribution of WMH, to further understanding of the relationship between MetS and structural brain changes.

Methods: Analyses were carried out on 308 participants (48.1% men, age: 71.0 ± 3.9 years) from the French longitudinal ESPRIT (Enquête de Santé Psychologique--Risques, Incidence et Traitement) study, who were free of cerebrovascular disease cognitive and functional impairment. Logistic regression models were used to examine the cross-sectional association between MetS (defined using the National Cholesterol Education Program-Adult Treatment Panel III criteria) and (1) WMH volumes, and (2) WMH volumes according to their localization in insulofrontal and temporoparietal regions.

Results: After adjusting for potential confounders, participants with MetS had a twofold increased chance of presenting with high levels of WMH volume compared with those without (odds ratio [OR] = 2.74, 95% confidence interval [CI]: 1.25-6.03). MetS was specifically associated with an increase of temporoparietal WMH volumes, but no association was found between MetS and WMH localized in the insulofrontal region.

Conclusion: Our findings suggest that effective management of MetS may reduce WMH accumulation in brain areas already vulnerable to the aging process.

Fig. 1

Flowchart diagram mapping the selection of the 308 healthy elderly participants included in the present analyses.

Fig. 2

Cross-sectional association between MetS and total WMH volumes and according to their localization in the brain (n = 308 participants). Results of logistic regression estimating odds of high levels of WMH in participants with MetS compared with those without MetS. M1: Model adjusted for sex, age, and total cranial volume. M2: M1+ adjusted for educational level, smoking habits, use of lipid-lowering drugs, cognitive performances in Mini-Mental State Examination, and APOE ε4/εX. Total WMH volumes were dichotomized according to the median = 0.7 mL, with high WMH levels defined by median = 1.75 (25th–50th range: 0.80–1.75), and low WMH levels defined as the reference (median = 0.30, 25th–50th range: 0.10–0.40). Temporoparietal and insulofrontal WMH were dichotomized according to the median values (0.11 and 0.37 mL, respectively). High levels of temporoparietal WMH defined by median = 0.38 (25th–50th range: 0.20–1.29), and low level defined by median = 0.03 (25th–50th range: 0.009–0.06). High levels of insulofrontal WMH defined by median = 1.11 (25th–50th range: 0.61–2.22), and low level defined by median = 0.13 (25th–50th range: 0.06–0.23).