Identification of Exercise-Related Signature Genes Potentially Associated with Cocaine Addiction by Integrating Bioinformatics and Mendelian Randomization Analysis

<b>Background</b>: Exercise is a promising non-pharmacological intervention for cocaine addiction but molecular mechanisms of exercise-related genes in addiction remain unclear. This study aimed to identify exercise-related signature genes for cocaine addiction and to assess the potential causal relationship between exercise and cocaine addiction using two-sample Mendelian randomization (MR) analysis. <b>Methods</b>: Midbrain transcriptomic data were analyzed for differentially expressed genes (DEGs) and intersected with exercise-related genes. Functional enrichment, protein-protein interaction (PPI) and immune infiltration analyses explored their roles while signature genes were screened via LASSO/Random Forest and validated by ROC curves. GSEA explored pathways and MR confirmed exercise's causal effect. <b>Results</b>: A total of 244 DEGs were identified, including 27 exercise-related, and six signature genes (CALM3, CCL2, CD44, CLIC1, JUN, VCAM1) showed AUC values between 0.714 and 0.868 in distinguishing cocaine-addicted individuals from controls. Functional analyses revealed enrichment in immune-inflammatory pathways, metabolic processes and neuro-immune interactions and immune infiltration analysis showed cocaine addicts had elevated pro-inflammatory cells, reduced regulatory cells and signature genes correlated with immune dysregulations. MR analysis suggested a statistically significant protective association between genetically proxied higher levels of exercise and cocaine addiction risk (<i>p</i> < 0.05). <b>Conclusions</b>: These six genes may be potential biomarkers and therapeutic targets, and exercise may protect against cocaine addiction by regulating immune-inflammatory responses, metabolic pathways and neuroplasticity, although further validation in larger, independent cohorts and experimental models is required.