Atopic eczema tied to higher risk of dementia in older adults

Having an atopic eczema appears to slightly increase one’s risk of incident dementia, particularly among older adults, suggests a study. Such risk further grows with the severity of atopic eczema.

“Patients with atopic eczema in a large, population-based primary care cohort had a small increased risk of incident dementia,” the researchers said. “Atopic eczema is common among older adults; therefore, future work should investigate the impact of screening patients with atopic eczema for cognitive impairment in older adulthood.”

This longitudinal cohort study was conducted to determine whether active atopic eczema is associated with incident dementia. A total of 1,767,667 individuals aged 60‒99 years registered with The Health Improvement Network, a primary care cohort in the UK, were included in the analysis.

During follow-up, dementia incidence was 57 per 10,000 person-years (PY) among adults with atopic eczema (12.1 percent of the population) relative to 44 per 10,000 PY among controls. In adjusted Cox proportional hazard models, this corresponded to a 27-percent higher dementia risk (hazard ratio [HR], 1.27, 95 percent confidence interval [CI], 1.23‒1.30). [J Am Acad Dermatol 2022;87:314-322]

Subgroup analyses of vascular dementia and Alzheimer’s disease revealed similar associations. This association remained even after adjusting for the use of systemic corticosteroids (HR, 1.29, 95 percent CI, 1.26‒1.33) and potential mediators (HR, 1.19, 95 percent CI, 1.16‒1.22). In addition, more severe eczema led to a greater dementia risk.

These findings are relevant since both atopic eczema and dementia are common among older adults, who happen to be the fastest-growing demographic group in the world. [https://bit.ly/3uZgFJt]

“The incidences of atopic eczema and dementia in our study are similar to those in other population-based reports with similar settings,” the researchers said. [Neurology 2020;95:e519-e531; Clin Exp Allergy 2021;51:471-482]

“Our results expanded upon two smaller studies that used the Swedish Twin Registry and a Taiwanese national insurance database,” they added. [Dement Geriatr Cogn Disord 2008;25:148-156; Ann Allergy Asthma Immunol 2021;127:200-205]

The present study was designed to determine whether an association between atopic eczema and dementia exists at the population level. Subsequently, the mechanism by which this skin condition contributes to dementia needs to be understood.

Mechanism and treatment

“We posit that it may be related to inflammation because patients with atopic eczema have higher levels of serum inflammatory markers, which have been linked to structural changes in the white matter, cognitive decline, and dementia,” the researchers said. [F1000Res 2017;6:1712; Psychol Med 2017;47:23-33; Neurology 2019;92:e1256-e1267; Brain Behav Immun 2021;91:81-88]

“Additionally, atopic eczema has been associated with poor sleep, which may be involved in the pathogenesis of dementia,” they added. [J Allergy Clin Immunol 2015;136:1170-1177; JAMA Pediatr 2019;173e190025; Biology (Basel) 2021;10:1127]

Dry-skin care is the first-line treatment for atopic eczema. Findings from previous studies suggested that emollients could reduce the serum levels of inflammatory markers among older adults. [J Am Acad Dermatol 2014;71:116-132; J Invest Dermatol 2017;137:1277-1285; J Eur Acad Dermatol Venereol 2019;33:2197-2201]

Several new targeted biologic treatments for severe atopic eczema may also reduce such risk should a causal link be found. The interleukin (IL)-4 or IL-13 blocker dupilumab, for instance, showed efficacy in lowering the serum levels of inflammatory markers among atopic eczema patients in a recent study. [J Allergy Clin Immunol 2019;143:155-172]

“The impact of the treatment of atopic eczema on the risk of dementia is unknown; therefore, additional research is needed to address this question of high clinical relevance,” the researchers said.