Poor skin barrier function was associated with a faster 10-year decrease in verbal memory in older adults, researchers reported in a study published in the Journal of Investigative Dermatology.
The pilot study evaluated the association between skin barrier function and cognition using data from the ongoing Baltimore Longitudinal Study of Aging.
The cohort included 237 participants 50 years of age and older who had skin barrier measurements and follow-up assessments from January 2019 through March 2020. The average age of participants was 76.8±10.1 years, 57.8% were women, and 73.0% self-identified as White.
Participants were asked to avoid caffeine, topical products, and smoking 3 hours before measurement. Transepidermal water loss (TEWL) was measured on the left volar forearm 10 cm from the wrist, and tape stripping was then performed. TEWL measurement was obtained after every 5 strips until TEWL reached 4 times baseline. The area under the curve (AUC) when TEWL was plotted against the number of tape strippings was the primary outcome.
Participants underwent cognitive testing at all visits, and 5 cognitive domain scores (verbal memory, attention, executive function, verbal fluency, and visuospatial ability) were computed from z-scores of standardized cognitive tests. All cognitive assessments concurrent with and within 10 years before the skin barrier measures were included. A mean of 7.3 years of retrospective data with 1018 cognitive assessments were available for longitudinal analyses.
Linear mixed effects models were used to assess the association between epidermal barrier function and each cognitive domain score. Fixed effects were included in adjusted models for skin barrier function, sex, age at skin barrier assessment, race, education, room temperature, humidity, season, body mass index, history of eczema, smoking, time, and the 2-way interactions between time with all other predictors.
A higher AUC, or worse barrier function, was associated with a faster 10-year decline in verbal memory (β=-.14, P =.048). Better skin barrier integrity was also associated with less annual decline in verbal memory (β=.021, P =.013). Similar trends were found for all other cognitive domains, but the associations were not significant.
Study limitations include the methods for measurement of skin barrier function among older adults, as the AUC was used as it incorporates TEWL and skin integrity. In addition, retrospective measures of cognition were analyzed owing to the recent introduction of skin barrier measures, and participants were predominantly White, well-educated, older adults.
“Poorer skin barrier function was associated with faster declines in verbal memory performance,” concluded the investigators. “Although observed effect sizes were small and associations for other domains of cognitive change were nonsignificant, all measures showed associations in the direction of hypothesized change, suggesting that this hypothesis should be further addressed in studies with repeated concurrent measures of epidermal barrier function and cognition.”
Disclosure: A study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Kim RW, An Y, Zukley L, et al. Skin barrier function and cognition among older adults. J Invest Dermatol. Published online January 11, 2023. doi:10.1016/j.jid.2022.11.023