Taiwan has been recognized as an “aged society” since 2018, and will step into a “super-aged society” in 2025. With the increase of aged population and longer life expectancy, the number of individuals with dementia is dramatically rising up. It should be noted that Alzheimer’s disease (AD) is the most common form of dementia, and the estimated global occurrence of AD will surpass 60 million by 2030. However, effective pharmacological treatments remain a challenge. Nevertheless, there are several lines of evidence suggesting that adequate physical and cognitive activities, and dietary interventions can slow down the deterioration of the symptoms. Therefore, early identification and detection of the cognitive changes in older adults can timely provide them with suitable medical regimen.
“Amnestic mild cognitive impairment (aMCI) is an intermediate phase between healthy aging and AD,” said first author Chia-Hsiung Cheng, a CGU associate professor in Department of Occupational Therapy. “AMCI is diagnosed by physicians based on the history taking and neuropsychological assessments. Particularly, deficits of episodic memory are the major features of this disease.” For example, the individuals are asked to learn and remember a couple of words. After a short delay, they have difficulties, more or less, to recall those previously learned items.
A complete neuropsychological assessment requires the individual’s sustained attention and motivation, both are declined in the older adults. Furthermore, for the purpose of the follow-up, re-evaluation of the cognitive tests with a short interval (e.g., 1-2 years) might be confounded by learning effects. To overcome these problems, Dr. Chia-Hsiung Cheng from Chang Gung University (Taiwan) and Dr. Rui Nouchi from Tohoku University (Japan) used a whole-head magnetoencephalography together with a pre-attentive oddball paradigm to study the brain activation in patients with aMCI.
“The advantage of oddball paradigm is its independence of individual’s attention and behavioral response to the targets,” said associate professor Chia-Hsiung Cheng. Despite of no engagement of attention in the experiment, this pre-attentive oddball task could also delicately assess the cortical functions of sensory memory and change detection. The results, published in the journal of CNS Neuroscience & Therapeutics in August 2021, revealed a delayed activation of inferior parietal lobule (IPL) in patients with aMCI compare to the healthy older adults, suggesting that the patient group needed more time to detect the changes of the environment. The researchers further found that more delayed activation of the left IPL was associated with lower scores of the verbal learning test.
Left: Dr. Cheng used magnetoencephalographic recordings with pre-attentive oddball paradigm discovered that compared to healthy controls (HC), patients with amnestic mild cognitive impairment (aMCI) demonstrated delayed activation of the inferior parietal lobule (IPL). Right: Among the patients with aMCI, more delayed activation of the left IPL was associated poorer verbal learning function (CNS Neuroscience & Therapeutics, 2021, DOI: 10.1111/cns.13691).
In recent years, Chang Gung University is devoted to establishing international collaboration and boosting global visibility. This research led by Department of Occupational Therapy in Chang Gung University together with Smart Aging Research Center in Tohoku University opens a new window for prospective studies to further clarify the role of IPL in the disease progression. A long-term application, if its role is precisely confirmed, might be the use of neural modulation to achieve brain plasticity and symptom amelioration.