Abstract Background Alzheimer’s disease (AD) patients often express significant behavioral symptoms: for this reason, accessible related biomarkers could be very useful. Neuroinflammation is a key pathogenic process in both AD and delirium (DEL), a clinical condition with behavioral symptoms resembling those of AD. Methods A total of n = 30 AD patients were recruited together with n = 30 DEL patients and n = 15 healthy controls (CTRL). Serum diazepam binding inhibitor (DBI), IL-17, IL-6, and TNF-α were assessed by ELISA. Results DBI serum levels were increased in AD patients with respect to CTRL (+ 81%), while DEL values were 70% higher than AD. IL-17 was increased in DEL with respect to CTRL (+ 146%), while AD showed dispersed values and failed to reach significant differences. On the other hand, IL-6 showed a more robust increase in DEL with respect to the other two groups (+ 185% and + 205% vs. CTRL and AD, respectively), and TNF-α failed to show any change. Conclusions DBI may be a very promising candidate for AD, perhaps marking psychomotor DEL-like symptoms, in view of developing future helping tool for practicing physicians. Furthermore, DBI rise in DEL offers novel cues for a better comprehension of the pathogenesis of this potentially fatal condition.