Brain stimulation used on a patient with Parkinsons.
(photo credit: Courtesy)
Simultaneous noninvasive stimulation of the brain’s motor and cognitive areas reduces the severity of “frozen movement” in patients with Parkinson’s disease, according to researchers at Tel Aviv Sourasky Medical Center, Tel Aviv University and Harvard University in Boston. Simultaneous stimulation also improved functional mobility and thinking better than motor stimulation alone or a placebo.
The study sheds light on the mechanisms of Parkinson’s disease, explained Moriah Dagan, a doctoral student in neuroscience at Tel Aviv University; Dr. Talia Herman; Prof. Jeff Hausdorff; and Prof. Nir Giladi. The researchers found that the neurodegenerative disorder is not just a motor disturbance, but also an illness affected by cognitive and even emotional parameters.
The preliminary results on 20 Parkinson’s patients were published this month in the journal Movement Disorders.
With current pharmacological and symptomatic treatment, the patient’s condition deteriorates over the years.
Symptoms include decreased walking speed and step length, as well as changes in walking rhythm and balance. Some patients suffer from a freezing of gait at some point. Stasis in walking is defined as a situation in which the patient is unable to progress with his feet and legs as if they were stuck to the floor, even though the patient wants to continue walking.
Walking stagnation significantly impairs mobility and independence, increases the risk of falls and causes a decline in the patient’s quality of life.
It affects about 80% of patients with advanced Parkinson’s.
Treatment of the phenomenon of stagnation is limited. Using external cues can help the patient overcome the stalemate, but these strategies do not prevent recurrence and are effective only as long as the cue is present.
Non-invasive brain stimulation – called transcranial direct-current stimulation, or tDCS – is a noninvasive, superficial excitation method of the brain, with a high level of safety.
This method uses very weak external electrical stimulation that safety studies have shown to be painless and safe. This method of brain stimulation is being widely used in a variety of studies dealing with disorders of the nervous system, such as stroke, chronic pain and depression.
Using tDCS of the prefrontal cortex was found to improve learning, reduce risk-taking behavior and improve response times during tasks requiring work memory. It has been tested on many diverse populations, both young and old, as well as in populations with different pathologies, such as Alzheimer’s disease, stroke, depression, schizophrenia and Parkinson’s.
Following the success of an initial trial, a follow-up, randomized, double- blind study was conducted at Sourasky that examined the effect of brain stimulation on walking stagnation and long-term motor and cognitive functions. The participants underwent intensive treatment with tDCS for 10 consecutive days, plus a period of more-conservative treatment once a week.
Before the start of the study and after each series of treatments, the participants underwent a comprehensive assessment of walking, balance and thinking functions, using wearable sensors and measuring frontal lobe function. The research used functional and near-infrared spectroscopy, which enabled real-time monitoring of objective measurements in the laboratory as well as in the patient’s natural environment.