New York, June 14
A study led by an Indian-American researcher has found that a few minutes of data recorded from a single electrode placed on top of the head may be sufficient to predict thinking problems, including dementia, in patients with Parkinson's disease.
Nandakumar Narayanan from the University of Iowa and his team of scientists believe that the new finding can help improve diagnosis of cognitive disability in Parkinson's disease (PD).
In addition, it can develop new biomarkers and targeted therapies for cognitive symptoms of the disease. Cognitive decline, including dementia, is a significant and underappreciated symptom of Parkinson's disease.
According to Narayanan, around 30 per cent of patients can have cognitive symptoms at the beginning of the disease, and up to 80 per cent will have cognitive problems at some point in their disease.
"Although we have quite a few effective treatments for the motor symptoms of Parkinson's, including medical therapies and deep brain stimulation, we have very few treatments for the cognitive aspects of Parkinson's disease," said Narayanan, MD, PhD, associate professor of neurology at the University of Iowa Carver College of Medicine.
The findings of the study, published in the Journal of Neurology, Neurosurgery & Psychiatry, said that EEG (electroencephalography), an inexpensive and non-invasive technology, might be useful for diagnosing cognitive impairment in PD patients.
"Traditional methods for diagnosing cognitive problems often involve time-consuming pen and paper tests and require a neurologist to administer and interpret the tests. In addition, because these traditional tests can be 'learned', they cannot be used repeatedly over time for the same patient," Narayanan, a member of the Iowa Neuroscience Institute, said.
In contrast, EEG can be done continuously over several hours or days.
EEG records the patient's frontal regions of the brains and quantify low-frequency brain waves known as delta and theta waves.
The team found that reduced strength of these specific brain waves when a patient is required to engage in thinking is strongly linked to cognitive dysfunction in PD.
Narayanan's team concluded that diminished cognitive function was correlated with diminished strength of low frequency brain waves while the patient was doing a task.
"Surprisingly, the effect was seen simply because the patient was required to pay attention to a cue and respond. I think this is the deep insight into why Parkinson's patients have cognitive problems: they fail to engage these basic response processes in the brain," Narayanan explained.
"That was very surprising to us, and it's helpful because it means we might be able to get information about cognitive function using the simplest version of this task where there's a cue, and the patient has to engage and respond. That process -- cue, engage, respond -- might be enough to determine where patients are on the cognitive status scale and whether they have the potential to improve."
Narayanan says this insight might also be an opportunity to help patients. Potentially "cueing" Parkinson's patients to engage in a task -- whether it's walking, talking or thinking, might improve how well they perform the task. If this is true, it would have important implications for the way rehabilitation, occupational, and speech therapists help patients with PD.
The study involved 100 PD patients across the full spectrum of cognitive function from healthy to dementia, and 49 demographically similar control participants.
