Gut microbiota dysbiosis at the interface of neuropsychiatric disorders and their dermatological comorbidities.

Neuropsychiatric disorders such as autism spectrum disorder (ASD), generalized anxiety disorder (GAD), major depressive disorder (MDD), and schizophrenia (SZ) frequently co-occur with dermatological conditions, including atopic dermatitis, psoriasis, rosacea, and chronic urticaria. The biologic basis remains incompletely understood. A growing body of evidence implicates gut microbiota dysbiosis as a shared pathogenic factor linking these conditions. This review synthesizes preclinical and clinical findings demonstrating consistent microbial alterations across both neuropsychiatric and dermatologic conditions, including fluctuations in alpha diversity, disrupted Firmicutes/Bacteroidetes ratios, and depletion of short-chain fatty acid (SCFA)-producing taxa such as Faecalibacterium, Roseburia, and Eubacterium species. These microbial shifts parallel elevations in inflammatory mediators such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-17 (IL-17), and cause perturbations in amino acid metabolism, altered glutamate-GABA signaling and increased branched-chain amino acids, indicating convergence on immune and metabolic pathways. Experimental rodent studies support the concept by demonstrating that microbiota dysbiosis can both impact psychiatric-like behaviors and cutaneous inflammation. Microbiota-targeted therapies such as probiotics show preliminary efficacy in improving symptoms across both domains. These findings support a gut microbiota-brain-skin axis and suggest that targeting gut dysbiosis may offer an integrated therapeutic approach for neuropsychiatric disorders and their dermatologic comorbidities.