Parkinson disease (PD) is a progressive neurodegenerative disorder marked by the loss of dopaminergic neurons in the substantia nigra. Clinically, PD presents with motor symptoms such as bradykinesia, tremor, and rigidity, which significantly compromise patients' daily function and quality of life. Deep brain stimulation (DBS) has become a cornerstone in the management of advanced PD, delivering high-frequency electrical stimulation to specific brain targets to alleviate motor deficits. However, conventional DBS operates with fixed parameters, lacking the ability to adapt in real-time to symptom fluctuations. This rigidity can lead to suboptimal outcomes including overstimulation or inadequate symptom control.Adaptive DBS (aDBS) represents an advanced therapeutic approach that continuously monitors neural activity, such as local field potentials (LFPs), and dynamically adjusts stimulation parameters through a closed-loop "sense-decode-stimulate" system. This facilitates personalized therapy that responds in real-time to the patient's clinical state. aDBS has been shown to not only enhance motor symptom control but also reduce stimulation-induced side effects such as dysarthria and dysphagia. Despite its promise, several clinical and technical challenges remain. These include the miniaturization of pulse generators, precision placement of flexible electrodes, reliable signal decoding and feedback, safety of compact high-energy batteries and wireless charging, and minimizing surgical invasiveness and related complications. Future developments in implantable brain-computer interface (BCI) technologies, such as integrated circuit-based implantable pulse generators, microelectrode array, high-performance computing, and secure high-bandwidth communication, hold disruptive potential that may benefit not only PD but also other neurological and psychiatric conditions including Alzheimer disease and depression. This article reviews the fundamental principles, clinical benefits, biomarker validation, trial design considerations, and technological advancements in aDBS systems, and discusses current limitations and future directions to guide further clinical translation.