Objective To investigate the effect of dexmedetomidine-assisted deep brain stimulation on the cAMP/PKA signal pathway in elderly patients with Parkinson's disease. Methods A total of 150 elderly patients with Parkinson's disease who underwent deep brain stimulation （DBS） at the Affiliated Brain Hospital of Nanjing Medical University from January 2021 to January 2025 were selected as the study subjects. The enrolled patients were randomly divided into Group A （75 cases） and Group B （75 cases） using the random-number table method. In Group B， dexmedetomidine was pumped before anesthesia induction， while in Group A， an equal-volume of saline was pumped. The patients were observed for 2 weeks after the operation and followed up for 6 months. The perioperative-related indicators of the two groups were compared， including subthalamic nucleus （STN） frequency， length of bilateral subthalamic nucleus physiological signals， coordinate error， perioperative hemodynamics ［before anesthesia induction （T₀）， after general anesthesia intubation （T₁）， and during anesthesia deepening （T₂）］， brain injury indicators （1 h before surgery， 1 d after surgery）， Ramsay sedation score （before entering the operating room， before surgery， during intraoperative localization testing， and at the end of surgery）， motor score of the Parkinson's syndrome scoring scale （UPDRS）， cognitive function， and cAMP/PKA signaling pathway （1 h before surgery， 2 weeks after surgery）. Results The recovery times of operation， unconsciousness， and spontaneous breathing in Group B were significantly shorter （P < 0.05）. There were no significant differences in STN frequency， bilateral STN electrophysiological signal length， and coordinate error between Group B and Group A （P > 0.05）. The mean arterial pressure （MAP） and heart rate （HR） in the T₀ ~ T₂ groups showed a decreasing trend. At T₁ and T₂， the MAP and HR in Group B were higher than those in Group A. Meanwhile， the bispectral index （BIS） in the T₀ ~ T₂ groups showed a trend of first decreasing and then increasing （P < 0.05）. There were no significant differences in BIS and SpO₂ at different times and between the two groups （P > 0.05）. Compared with one hour before operation and one day after operation， the levels of serum central nervous system - specific protein （S - 100β）， neuron-specific enolase （NSE）， and homocysteine （Hcy） in both groups were higher， but these levels were lower in Group B. In contrast， the level of serum uric acid （UA） was lower overall， but it was higher in Group B （P < 0.05）. In both groups， the Ramsay sedation scores gradually increased from the time of entering the operating room until the end of the operation. At the time of the intraoperative localization test and the end of the operation， the Ramsay sedation scores in group B were significantly higher than those in group A （P < 0.05）. When compared to the scores 1 hour before the operation and 2 weeks after the operation， the Unified Parkinson's Disease Rating Scale （UPDRS） scores in both the unilateral and bilateral switch states were lower， with a more pronounced decrease in group B （P < 0.05）. Similarly， the scores on the Montreal Cognitive Assessment Scale （MoCA） in both groups were higher when compared to the pre-operation （1 hour before） and 2-week post-operation scores， particularly in group B （P < 0.05）. Moreover， the levels of serum cyclic adenosine monophosphate （cAMP） and protein kinase A （PKA） in both groups were higher compared to those 1 hour before the operation and 2 weeks after the operation， especially in group B （P < 0.05）. Conclusions Dexmedetomidine can stabilize the perioperative hemodynamic indexes， regulate the cAMP/PKA signaling pathway， and improve the indexes of brain injury in elderly patients with Parkinson's disease undergoing deep-brain stimulation. Additionally， dexmedetomidine exhibits a favorable target-positioning effect， which shortens the operation time， the time of consciousness disappearance， and the recovery time. It also enhances the degree of sedation and improves the cognitive and motor functions of patients.