Early detection and intervention is crucial for people with Parkinson’s disease, as it can lead to mild cognitive impairment or dementia, seriously affecting their daily activities, Wu Ruey-mei (吳瑞美), convener of National Taiwan University Hospital’s center for Parkinson’s and movement disorders, said yesterday.
Wu made the remarks at a press conference held in Taipei to celebrate the sixth anniversary of the center and to present its research results.
Parkinson’s disease is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity and slowness of movement, but non-motor, neuropsychiatric symptoms that disturb patients’ memory, executive function, visual perception, speech and social cognition are also common.
Wu said studies have shown that about 30 percent of people with Parkinson’s disease, usually years after the onset, develop mild cognitive impairments — they start to forget things easily, get lost in familiar places, have problems planning activities and have a hard time understanding other people’s speech.
The center assessed the neurocognitive functions of patients with Parkinson’s disease with neuropsychiatric evaluation tools and found that patients can develop executive dysfunctions in the early stages of the disease.
“Social cognition might be negatively affected too. The patients, for example, cannot accurately infer what others think or sense their emotions, and this gap in their understanding is often the cause of friction between the patients and their families,” Wu said.
The difference between Parkinson’s disease with dementia and Alzheimer’s disease, also a neurodegenerative disorder and the most common form of dementia, is that patients with the former tend to suffer dysfunctions pertaining to the execution of speech and visual perception as early-stage cognitive impairments, and it is only in the latter stages that memory retrieval deficit develops.
Alzheimer’s disease, on the other hand, is characterized by memory loss as the main early-stage symptom.
Deep brain stimulation, an alternative to medication treatment for Parkinson’s disease patients, was also discussed at the press conference.
Tai Chun-hwei (戴春暉), an attending physician of neurology and a member of the medical team at the center, said it has been discovered that deep brain stimulation can improve a patient’s motor functions by implanting in the brain probes that send electrical impulses to modulate the brain’s abnormal electrophysiological activities.
How the mechanism works is not clear, with researchers suspecting it stimulates the secretion of dopamine, which patients with Parkinson’s disease lack.
Tai said the research team has showed that deep brain stimulation regulates the increase in neuronal burst activity in a part of the brain called the subthalamic nucleus and that it is highly correlated with abnormalities in T-type Ca(2+) channels in the membrane of the nerve cells.
The team found pharmacological blockade of the channels with abnormalities can effectively reduce motor deficits in an animal experiment and concluded that “the modulation of subthalamic T-type Ca(2+) currents and the consequent burst discharges” may be the reason why deep brain stimulation works.
Tai said the hospital has conducted more than 100 deep brain stimulation surgeries, but while it can greatly improve patients’ motor symptoms that are resistant to drugs, a reduced dose of dopamine medication is still required.