Psoriasis and atopic dermatitis are chronic inflammatory skin diseases associated with systemic inflammation and increased risk of neurodegenerative disorders. Systemic therapies for these conditions target immune pathways implicated in neuroinflammation, but their association with dementia risk remains unclear.

We conducted a retrospective cohort study using the TriNetX electronic health record network, evaluating adults aged 65–95 years with psoriasis, atopic dermatitis, or osteoporosis between 2005 and 2025. Each disease cohort was divided into systemic treatment and no systemic treatment groups, with matched general control cohorts. The primary outcome was incidence of all-cause dementia, with secondary outcomes including Alzheimer’s disease, vascular dementia, and nonvascular dementia subtypes. Propensity score matching was applied for demographic and comorbidity variables.

Systemic treatment in psoriasis and atopic dermatitis was associated with lower relative risks of Alzheimer’s disease, vascular dementia, and nonvascular dementia compared with untreated cohorts. In contrast, no reduction in dementia risk was observed among treated osteoporosis patients. Absolute risk reductions were modest, and number-needed-to-treat values were high, indicating limited clinical effect size.

These findings suggest that observed associations may reflect a combination of biologic immune modulation and treatment-related selection factors, including healthier baseline profiles and greater healthcare engagement among treated patients. Prospective studies are needed to clarify causality and assess whether systemic anti-inflammatory therapies influence long-term cognitive outcomes.

Sanat Subhash is a medical student at Northeast Ohio Medical University with research experience in dermatology and large-scale electronic health record analyses.

He has authored multiple research presentations and manuscripts focusing on epidemiology and translational clinical research.