Because of their study's findings, the researchers urged clinicians to screen patients with atopic dermatitis (AD) for cognitive dysfunction.
Middle-aged and older adult patients with atopic dermatitis (AD) have an increased risk of all-cause dementia and Alzheimer’s disease-related dementia, according to a meta-analysis published in PLoS One.
The researchers explained that recent studies have suggested a potential link between AD and cognitive dysfunction in the older adult population, including dementia, all-cause dementia, and mild cognitive impairment. They noted that some studies claimed that AD directly contributes to cognitive impairment through neuroinflammation and oxidative stress, while others claim that the disease states share risk factors, like age, genetic vulnerability, and lifestyle factors.
To clarify the nature of the relationship, the researchers conducted a meta-analysis to evaluate the association between AD and cognitive dysfunction in middle-aged (45-59 years old) and older (60 years and up) adults. Through this study, they aimed to understand the strength of the association, the underlying mechanisms, and its implications for clinical practice and public health.
To do so, the researchers conducted a comprehensive search of databases PubMed, Embase, and Web of Science up to March 2023 using related search terms. To determine which studies to use, 2 authors independently screened titles and abstracts. After, they then conducted full text screenings. The researchers excluded studies that reported other outcomes than cognitive dysfunction risk, were duplicates, were conducted on animals, did not provide sufficient data, or were conducted on patients with different dermatological diseases.
The researchers initially identified 1853 eligible articles, which they narrowed down to 48 for full-text screening. Ultimately, they selected 5 studies, which contained 8,595,252 participants with AD and corresponding controls. The participants ranged in mean age from 45 to 74 years, and the prevalence of AD ranged from 0.4% to 12%.
From their analysis, they found that patients with AD had a higher risk of developing all-cause dementia (HR, 1.16; 95% CI, 1.10-1.23; P < .001; I2 = 54.5%) and Alzheimer’s-related dementia (HR, 1.28; 95% CI, 1.01-1.63; P < .001; I2 = 95.8%). On the other hand, patients with AD did not have a high risk of developing vascular dementia (HR, 1.42; 95% CI, 0.99-2.04; P < .001; I2 = 96.0%).
Additionally, the researchers conducted subgroup analyses by region and study design. Through this, they found the association between AD and all-cause dementia to be significant in Europe (HR, 1.14; 95% CI, 1.04-1.24; P = .004; I2 = 46.5%); conversely, the association was not significant in Asia (HR, 1.45; 95% CI, 0.85-2.47; P = .173; I2 = 79.7%. Also, their subgroup analysis by study design showed that the association between AD and Alzheimer’s disease-related dementia was significant in prospective cohort studies (HR, 1.41; 95% CI, 1.04-1.90; P = .025; I2 = 97.3%) but not in non-prospective cohort studies (HR, 1.13; 95% CI, 0.93-1.36; P = .229; I2 = 8.3%).
Based on these findings, the researchers advised clinicians to be aware of the association and screen those with AD for cognitive dysfunction using validated tools like the Mini-Mental State Examination or the Montreal Cognitive Assessment. They also explained that clinicians should be aware of the possible underlying mechanisms related to the association, like chronic inflammation, oxidative stress, and sleep disturbance.
“Therefore, clinicians should adopt a holistic approach to manage patients with AD and cognitive dysfunction, not only treating their skin symptoms but also addressing their systemic and psychological comorbidities,” the authors wrote.
The researchers also acknowledged their study’s limitations, one being that the generalization and precision of their findings may be limited due to the small number of studies included. Similarly, the meta-analysis only contained studies from the United Kingdom, South Korea, Sweden, and Taiwan, meaning their findings may not reflect the prevalence and impact of AD and cognitive dysfunction in other countries. Because of the limitations, the researchers instructed readers to interpret their findings with caution.
“...There is substantial heterogeneity across the studied arms that needs to be further explored,” the authors concluded. “More high-quality studies are needed to confirm our findings and to elucidate the underlying mechanisms linking AD and cognitive impairment.”
Zhou Q, Yang D, Xiong C, Li X. Atopic dermatitis and cognitive dysfunction in middle-aged and older adults: A systematic review and meta-analysis. PLoS One. 2023;18(10):e0292987. doi:10.1371/journal.pone.0292987