Life-span Developmental Psychology and Cognitive Neuroscience
We mainly focus on the following four fields:
1. Cognitive aging and relative neural mechanisms;
2. Early detection and intervention of cognitive impairments in older adults;
3. Cross-cultural study of cognitive aging;
4. Mental health models and relative factors in community-dwelling older adults.
The following four studies correspond to the above-mentioned research areas and are the latest and representative studies of our group.
Investigating the effectiveness of video games combined with aerobic exercise to enhance memory discrimination in the elderly and its brain neural mechanism
At this stage, there is a large body of research that attempts to take advantage of the brain plasticity still retained by older adults in order to slow down the process of cognitive decline and even improve cognitive performance. Aerobic exercise training and 3D video game training have been found to be very promising for situational memory, especially for similar memory discrimination. It is then an open question whether 3D video game training combined with aerobic exercise in older adults can achieve better results than single cognitive or motor training.
To this end, we conducted a 4-month combined intervention study in which community-dwelling older adults were trained with aerobic cycling combined with 3D video games simultaneously, with a single aerobic exercise training group, a single 3D video game training group and a negative control group (not receiving any training) as controls.
The results found that the simultaneous combined intervention showed superior effects in improving memory discrimination compared to the single aerobic exercise intervention or the single 3D video game intervention. The study revealed that aerobic exercise-induced hippocampal structural plasticity and 3D video game-induced functional plasticity in the DMN network (Figure 1) may be the neural basis for the synergistic effect, suggesting the complexity of plasticity mechanisms in the human brain. The study confirmed the high compliance and good feasibility of the combined simultaneous intervention model, which could help design more effective intervention programs and develop more targeted intervention devices to improve cognitive function with increasing age and prevent and delay the onset of dementia.
Figure 1. Schematic diagram of the front default network and the back default network (a) and their functional connectivity with intervention (b-c)
Alterations in working memory-related potentials and resting-state EEG characteristics of cognitive complaints
We have also conducted studies to find more sensitive EEG indicators for early screening of cognitive decline. Individuals with normal performance on objective cognitive tests but subjective cognitive decline (SCD) may evolve into pathological cognitive decline and be at increased risk of developing Alzheimer's disease (AD) and related dementia (ADRD). Decline in working memory is widely recognized as an early sign of pathological cognitive decline. This study hypothesized that older adults with SCD already exhibit abnormalities in the neurocognitive processing basis of working memory.
Cognitively healthy community-dwelling older adults were divided into SCD and normal older adult groups and subjected to a delayed matching task (DMS) and closed-eye state EEG signals (EEG). The results showed no significant differences in behavioral performance between the SCD and control groups on neuropsychological tests and DMS tasks. However, the SCD group showed enhanced right frontal target-related P300 effects during working memory retrieval and higher frontal theta power at rest. In all older adults, higher theta power was associated with poorer working memory performance.
Our findings suggest subtle pathophysiological changes in working memory-related potentials and resting-state theta power in older adults with SCD, which has important implications for predicting risk and early intervention in older adults in the preclinical phase of ADRD.
Figure 2. Differences in working memory-related potentials between healthy controls and SCD
Differences between Eastern and Western cultures in encoding objects in an imagined social environment
It has been shown that East Asians are more inclined to process contextual information than individuals in Western cultures. To explore this difference, the present study used a contextual memory task that required learning object images in social contexts (i.e., rating objects in imagined social or experiential scenarios).
By studying object images in social contexts (i.e., rating objects in imagined social or experiential scenarios), our recent study showed that younger and older Chinese participants had an age-invariant advantage in memory for encoding contexts compared to Canadian participants. To investigate whether such cultural differences also occur during encoding, the current study analyzed encoding performance and its relation to subsequent memory based on the same data from the same sample for the same task.
Results showed that during encoding, Chinese participants rated objects higher, took longer, and reported more vividly encoded background images relative to Canadian participants. In addition, only Chinese participants rated objects with a recognition context higher during retrieval and more slowly relative to those with a misrecognition context. For Chinese participants, mainly older adults, slower ratings were only associated with better contextual memory and not with item memory. Importantly, the contextual memory advantage disappeared for the Chinese participants after controlling for encoding differences.
Taken together, these results suggest that the Chinese memory advantage for social situations may stem from the construction of detailed and meaningful object-context associations during encoding.
Figure 3. Correlation between scoring reaction time and memory performance
Effects of loneliness, social isolation, and associated gender differences on the risk of developing cognitive impairment in Chinese senior citizens
Whether loneliness and social isolation independently predict the risk of cognitive impairment after advanced age has been a question worth exploring, and for this reason, our group opened a study to explore the correlation between the two.
The sample of this study consisted of 2,732 cognitively intact older adults aged 80 years and older from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2002-2018 with a mean follow-up time of 4.24 years. Loneliness was measured by a single question about how often the respondent felt lonely. Social isolation was defined by marital status, frequency of visits from family members, and participation in social activities. Cognitive impairment was defined by the scores of the Brief Mental Status Examination Scale (MMSE).
The results showed that social isolation independently predicted a higher risk of subsequent cognitive impairment. Importantly, although there was no main effect for loneliness, a significant interaction between gender and loneliness suggested that increased loneliness was associated with a higher risk of cognitive impairment for men, but not for women. To prevent cognitive impairment and promote healthy longevity, older adults who are socially isolated should receive more attention, and men who often feel lonely should receive more emotional support.