Neurodegeneration and cancer are fundamentally distinct disorders: one signifies gradual neuronal loss while the latter signifies uncontrolled cell growth and survival. However, emerging evidence explores an inverse association between these conditions, suggesting that they do not arise from independent biological processes. Understanding the context-dependent behaviour of major pathways (for example, p53, PI3K/AKT/mTOR, Wnt, and immune–stress signaling) remains pivotal in elucidating the relationship between these two diseases. Pathways promoting early-life fitness, tissue repair, and tumor suppression in dividing cells can become detrimental later in life for post-mitotic neurons. Cross-species genomics studies reveal how evolution has repeatedly adapted these shared networks to balance cancer resistance with survival. Research on species exhibiting exceptional longevity and disease resistance, including naked mole rats and bowhead whales, shows that cancer resistance and longevity are not fixed traits but rather are controlled by precise regulatory mechanisms. In this review, we integrate insights from broad species genomics and multi-omic and single-cell studies to understand how evolutionarily conserved molecular crosstalks diverge at the interface of cancer and neurodegeneration.

Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic inflammatory diseases resulting from complex interactions between host genetics, environmental factors, immune dysregulation, and the gut microbiome. Among environmental exposures, antibiotics have emerged as important factors of IBD risk and disease course because of their profound effects on intestinal microbial communities. This review synthesizes current evidence on the class-specific effects of antibiotics on IBD, integrating epidemiological, mechanistic, and clinical studies to examine how different antibiotic classes influence disease susceptibility, progression, and microbiome recovery. Current evidence indicates that antibiotic-associated IBD risk varies according to antibiotic class, cumulative exposure, age at exposure, and antimicrobial spectrum, with broad-spectrum and anti-anaerobic agents showing the strongest associations. Mechanistically, antibiotics promote dysbiosis by depleting beneficial commensal bacteria, disrupting microbial metabolite production, expanding pathobionts and the intestinal resistome, and impairing epithelial barrier integrity and immune homeostasis. The review also discusses microbiome-preserving and microbiome-restorative approaches, including antimicrobial stewardship, fecal microbiota transplantation, prebiotics, probiotics, synbiotics, postbiotics, and dietary interventions, as potential strategies to mitigate antibiotic-associated dysbiosis. Overall, the evidence highlights the class-specific effects of antibiotics in IBD and underscores the importance of microbiome-informed antimicrobial stewardship and precision therapeutic strategies to optimize patient outcomes while minimizing long-term disruptions of host–microbiome homeostasis.