Atopic dermatitis and cognitive dysfunction in middle-aged and older adults: A systematic review and meta-analysis

BACKGROUND: Atopic dermatitis (AD) is a common chronic inflammatory skin disease that affects adults worldwide. Recent evidence suggests that AD may be associated with cognitive dysfunction, but the results of individual studies have been inconsistent. This systematic review and meta-analysis aimed to evaluate the association between AD and cognitive dysfunction in middle-aged and older adults. METHODS: To find relevant research, a comprehensive search of electronic databases from the beginning to March 2023 was carried out. Data were taken from studies that were eligible, and a meta-analysis was done to determine the pooled hazard ratio (HR) and 95% confidence interval (CI). RESULTS: We searched three databases and found a total of 15 studied arms included in 5 cohort studies with over 8.5 million participants were included in the analysis. The results showed that individuals with AD had a higher risk of developing dementia of all-cause dementia (pooled hazard ratio (HR) = 1.16; 95% CI, 1.10–1.23,P<0.001) and the Alzheimer type (pooled HR = 1.28; 95% CI, 1.01–1.63,P<0.001) but not vascular dementia (pooled HR = 1.42; 95% CI, 0.99–2.04,P<0.001). Subgroup analyses showed that the association between atopic dermatitis and all-cause dementia was significant in Europe (P = 0.004) but not in Asia (P = 0.173) and was significant in prospective cohort studies (P<0.001) but not in non-prospective cohort studies (P = 0.068). Sensitivity analysis and publication bias detection confirmed the reliability of the overall findings. CONCLUSIONS: In conclusion, this study demonstrated that AD was associated with increased risk of cognitive dysfunction, particularly dementia of the Alzheimer type and all-cause dementia, in middle-aged and older participants. Further research is needed to understand the mechanisms behind this association and its potential implications for clinical practice. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, identifier (CRD42023411627).