Blood pressure and sodium: Association with MRI markers in cerebral small vessel disease

Abstract

Dietary salt intake and hypertension are associated with increased risk of cardiovascular disease including stroke. We aimed to explore the influence of these factors, together with plasma sodium concentration, in cerebral small vessel disease (SVD). In all, 264 patients with nondisabling cortical or lacunar stroke were recruited. Patients were questioned about their salt intake and plasma sodium concentration was measured; brain tissue volume and white-matter hyperintensity (WMH) load were measured using structural magnetic resonance imaging (MRI) while diffusion tensor MRI and dynamic contrast-enhanced MRI were acquired to assess underlying tissue integrity. An index of added salt intake (P = 0.021), pulse pressure (P = 0.036), and diagnosis of hypertension (P = 0.0093) were positively associated with increased WMH, while plasma sodium concentration was associated with brain volume (P = 0.019) but not with WMH volume. These results are consistent with previous findings that raised blood pressure is associated with WMH burden and raise the possibility of an independent role for dietary salt in the development of cerebral SVD.

Figure 1.

Representative magnetic resonance imaging (MRI) data and tissue segmentation. (A) Fluid-attenuated inversion recovery (FLAIR) image, (B) tissue masks superimposed on FLAIR image, (C) fractional anisotropy map, (D) contrast agent concentration curves obtained from dynamic contrast-enhanced MRI (DCE-MRI); y-axes scales for the sagittal sinus plasma concentration and normal-appearing tissue concentration curves are shown on the left and the right, respectively.

Figure 2.

Flow chart showing recruitment to the Mild Stroke Study 2. MRI, magnetic resonance imaging; TIA, transient ischemic attack.

Figure 3.

Relationship between white-matter hyperintensity (WMH) volume and pulse pressure (PP), diagnosis of hypertension, and salt intake score. The association between WMH volume and PP (Spearman’s R = 0.26, P < 0.001) survived correction for age and all other factors listed in Table 2. ICV, Intracranial volume.