<p>Alzheimer’s disease (AD) is a neurodegenerative disorder causing progressive neuronal damage. Incidence rises with age, and early diagnosis is difficult. This study examined DLX6-AS1 clinical relevance and regulatory mechanism in AD, and its interaction with miR-204-5p in AD pathology. It offers new insights into early diagnosis and treatment. A total of 133 <span>AD</span> patients and 105 healthy controls were selected. Their serum levels of DLX6-AS1 and miR-204-5p were analyzed using quantitative polymerase chain reaction. β-amyloid (Aβ)_1–42-induced SH-SY5Y neuronal injury and okadaic acid (OA)-induced Neuro-2a tau abnormal phosphorylation models were constructed. The role/function of DLX6-AS1/miR-204-5p axis was then investigated using cell counting kit-8, flow cytometry, western blotting, enzyme-linked immunosorbent assay and a dual-luciferase reporter gene assay. AD patients had higher serum DLX6-AS1 and lower miR-204-5p levels. DLX6-AS1 showed an AUC of 0.838 for AD diagnosis. DLX6-AS1 levels were negatively associated with cognitive function, brain structural integrity, and benign pathology—and positively associated with disease severity, functional impairment, and pathological markers. In AD cell models, DLX6-AS1 was upregulated. Silencing it promoted cell proliferation, reduced apoptosis and oxidative stress, improved mitochondrial and synaptic function, decreased tau phosphorylation, and enhanced microtubule stability and axonal transport. Dual-luciferase assays confirmed direct binding between DLX6-AS1 and miR-204-5p. Co-inhibition reversed the protective effects of DLX6-AS1 silencing. Serum DLX6-AS1 is a potential biomarker for early diagnosis and assessment of AD. It regulates Aβ-induced neuronal damage and tau phosphorylation by targeting miR-204-5p, offering a new mechanism target for AD molecular therapy.</p>