Min-Ji Park used to spend her days sitting quietly, watching time slip by. The 63-year-old from Gyeonggi Province, South Korea, was diagnosed with Parkinson's disease three years ago, and like many patients, she struggled not just with trembling hands and slow movements, but with something harder to see: a deep sadness and loss of interest in life.
Then she joined a small study at Korea University Ansan Hospital that changed how doctors think about treating these invisible symptoms.
Researchers there found that a simple brain therapy called transcranial direct current stimulation, or tDCS, could cut depression in Parkinson's patients by more than half while also helping them move more in their everyday lives. The study followed 20 patients over several weeks, and the results were striking.
tDCS works by sending a mild electrical current through electrodes placed on the scalp. It is not surgery, does not require anesthesia, and causes minimal discomfort. Professor Ho Kyung Yoon of the Department of Psychiatry and Professor Do Young Kwon of the Department of Neurology led the team. They delivered 10 treatment sessions, three times per week, targeting brain areas that control emotions.
After treatment, depression dropped by about 54 percent. Anxiety fell by roughly 38 percent, and apathy — a condition where patients feel unmotivated and lose interest in things they once enjoyed — improved by around 25 percent. Even motor symptoms like stiffness and slowness improved by about 35 percent.
But the researchers did not stop at asking patients how they felt. They gave everyone smart bands to wear on their wrists, similar to fitness trackers. These devices recorded step counts and sleep patterns in real time, outside the clinic walls.
And here is what surprised them: the patients were not just feeling better — they were actually moving more. Daytime physical activity increased significantly after treatment.
The key link, they discovered, was motivation. Reductions in apathy predicted increased daily activity more strongly than improvements in depression did. In other words, when patients felt more driven to do things, they naturally moved more — no matter their age or how long they had lived with Parkinson's.
"Patients with Parkinson's disease often experience substantial declines in daily functioning and quality of life due not only to motor symptoms but also to nonmotor symptoms such as depression and apathy," said Professor Yoon. "Our findings demonstrate that noninvasive brain stimulation can improve emotional symptoms while also increasing patients' real-world activity levels."
Professor Kwon added that the study shows how valuable it is to look at patients' real lives, not just what happens during doctor visits.
"Wearable-based assessment may play an important role in enabling more precise monitoring and supporting personalized treatment strategies," he said.
The findings were published in the journal Acta Neuropsychiatrica. For patients like Min-Ji, the implications are personal. After treatment, her family noticed she was walking around the house more, picking up old hobbies, and smiling again.
Small steps, the researchers say, can make a big difference.