From Skin to Brain: Key Genetic Mediators Associating Cutaneous Inflammation and Neurodegenerative Diseases

Chronic inflammatory skin diseases and neurodegenerative disorders share overlapping genetic, immunologic, and metabolic pathways that may predispose individuals to cognitive decline. This review synthesizes current human genomic, transcriptomic, and bioinformatic evidence linking psoriasis, rosacea, atopic dermatitis, and bullous pemphigoid with Alzheimer's and Parkinson's disease. Literature from PubMed, IEEE Xplore, and Google Scholar was examined, prioritizing studies integrating genomic, transcriptomic, and proteomic analyses. Among inflammatory dermatoses, psoriasis exhibits the strongest overlap with dementia genetics, with shared susceptibility loci including APOE, IL12B, and HLA-DRB5, and transcriptional regulators such as ZNF384 that converge on IL-17/TNF signaling. Rare-variant and pleiotropy analyses further implicate SETD1A and BC070367 in psoriasis-Parkinson's comorbidity. Rosacea demonstrates upregulation of neurodegeneration-related proteins SNCA, GSK3B, and HSPA8, together with shared regulatory hubs (PPARG, STAT4, RORA) driving NF-κB/IL-17/TNF-dependent inflammation. In atopic dermatitis, rare FLG variants interacting with BACE1 suggest a mechanistic bridge between barrier dysfunction and amyloidogenic processing. Bullous pemphigoid reveals an HLA-DQB1*03:01-mediated immunogenetic link hypothesis and cross-reactive autoantibodies targeting BP180 (collagen XVII) and BP230, highlighting an autoimmune route of neurocutaneous interaction. Other inflammatory and neurodegenerative diseases with currently weak or limited genetic evidence are also discussed, as they may represent emerging biological pathways or potential therapeutic targets within the skin-brain connection in the future. The aim of this work is to help clarify these genetic links and to advocate for the routine cognitive assessment of affected patients, enabling early detection, improved long-term quality of life, and the potential for timely therapeutic intervention.