Long-Term Effects of Deep Brain Stimulation in Parkinson's Disease: A Five-Year Study

A comprehensive five-year study involving 49 researchers from 30 medical and academic institutions has demonstrated that deep brain stimulation (DBS) targeting the subthalamic nucleus provides sustained motor improvements in patients with Parkinson's disease. The research, published in JAMA Neurology, analyzed data from a carefully designed clinical trial that initially involved a 12-week double-blind, sham-controlled phase, followed by an open-label follow-up over five years.

The study included 191 patients across 23 U.S. centers, with an average age of 60 years, predominantly male (73%). Participants underwent bilateral implantation of DBS devices with a constant current system. During the initial phase, patients were randomized in a 3:1 ratio to receive either active stimulation or subtherapeutic settings, in both medicated and unmedicated conditions.

Results showed a significant reduction in motor symptoms, with UPDRS-III scores (motor examination) decreasing by 51% at one year and by 36% at five years in the medication-off, stimulation-on state. Activities of daily living also improved markedly at one year (41%) and remained better than baseline at five years (22%). Dyskinesia severity decreased substantially, and medication doses were reduced by 28% over the five-year period.

Furthermore, the study observed sustained improvements in tremor, rigidity, and bradykinesia, although gait and some other symptoms showed less durable effects over time. Patient satisfaction remained high throughout the study, averaging 94%, and perceived benefits were reported by patients, caregivers, and physicians.

Safety data identified infections and procedural complications as the most common serious adverse events, with some cases of cerebral hemorrhage, seizures, and a suicide attempt related to the procedure. A total of ten deaths occurred during the follow-up, none of which were attributed to the study.

The authors concluded that deep brain stimulation targeting the subthalamic nucleus offers long-term motor benefits in Parkinson's disease, with some attenuation of effects over time but overall sustained improvements in quality of life. The findings support DBS as a viable long-term treatment option, reducing medication needs and improving daily function, even as the disease progresses.