Sodium in the Skin and Atopic Dermatitis

The goal of this observational study is to understand factors associated with skin sodium storage in healthy adults and people with atopic dermatitis ages 50 and above. The study is designed to test whether diet and skin barrier function are associated with skin sodium concentration and whether skin sodium concentration is linked to atopic dermatitis and immune profiles over time. Participants will be asked to complete questionnaires, provide bio samples, and undergo non-contrast sodium MRI at 2-3 time points over 3-24 months.

The central hypothesis of this proposal is that excess dietary sodium (consumed primarily as salt) is concentrated in the skin as a physiologic response to poor barrier function, and that high levels of skin sodium worsen atopic dermatitis. The study will recruit 90 individuals (30 healthy participants, 30 with mild atopic dermatitis and 30 with severe atopic dermatitis) and follow them to identify factors associated with skin sodium storage. Diet will be evaluated using food frequency questionnaires and urine biomarkers, skin sodium concentration will be measured using a non-invasive sodium MRI technique, and atopic dermatitis activity and severity will be measured using multiple patient-reported outcomes and clinician scores. Participants without atopic dermatitis will be asked to visit the research site 4 times over 3 months. Participants with atopic dermatitis will be additionally asked to complete monthly severity scores for up to 24 months total and to visit the research site an additional 2 times when their disease severity changes. The first specific aim will evaluate the association between dietary sodium intake and skin barrier function on skin sodium concentration. The primary analysis will use regression models to determine the association between dietary sodium intake and skin sodium concentration across 2-3 time points. The association with skin barrier function will also be evaluated. The second specific aim will evaluate the extent to which skin sodium is associated with atopic dermatitis severity and persistence. The analysis will use regression models to determine the association between skin sodium and atopic dermatitis prevalence and severity. It will also examine immune profiles associated with skin sodium.