Acitretin shows promising potential in Alzheimer's disease: retinoid-driven modulation of amyloid processing, neuroinflammation, and translational prospects.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder driven by the convergence of amyloid-β (Aβ) accumulation, tau hyperphosphorylation, synaptic failure, and chronic neuroinflammation, for which effective disease-modifying therapies remain elusive. Increasing evidence identifies dysregulated retinoid signaling as a critical yet underexplored contributor to AD pathogenesis. Retinoic acid, acting through retinoic acid receptors (RARs) and retinoid X receptors (RXRs), is essential for maintaining neuronal homeostasis, synaptic plasticity, and neuroimmune equilibrium in the adult central nervous system. In AD, impairment of RAR/RXR signaling shifts amyloid precursor protein (APP) processing toward amyloidogenic pathways, sustains NF-κB-driven inflammatory cascades, and promotes microglial dysfunction, thereby accelerating the progression of neurodegenerative processes. This review integrates mechanistic, preclinical, and translational evidence supporting acitretin, a second-generation synthetic retinoid, as a multi-target therapeutic candidate for AD. Acitretin enhances ADAM10-mediated non-amyloidogenic APP cleavage, increases soluble APP-α production, and reduces Aβ generation in transgenic AD models, while concurrently modulating microglial activation to attenuate pro-inflammatory cytokine signaling, including IL-6 and TNF-α, and preserve synaptic integrity. Importantly, biomarker-based clinical studies demonstrate increased cerebrospinal fluid APP-α following acitretin administration, confirming central target engagement in humans. Although definitive clinical efficacy remains to be established, acitretin's pleiotropic mechanism, established pharmacological profile, and biomarker responsiveness position it as a promising repurposed candidate within biomarker-guided and combination-based therapeutic strategies for AD.