Individual development is a lifelong process that involves multidimensional and multidirectional changes, with gains and losses at different ages. For adults, the cognitive intelligence gradually decreased with advancing aging, mostly in an inverted U-shaped curve, while emotional intelligence was relatively well-preserved or even improved during aging. Cognitive intelligence and emotional intelligence were generally regarded as different aspects of the human abilities. Considering that the cognitive intelligence and emotional intelligence exhibited distinct trajectories of development, our study tried to explore the adaptive significance of the distinct developmental trajectories. More importantly, we tried to investigating whether the human brain at different ages exhibited different underpins of cognitive and emotional intelligence from young adults to the middle-aged group, especially in terms of the morphological similarity networks.
In the study 1，we recruited 67 healthy participants (aging 18-64, divided into young adults and middle-aged group), who finished structural Magnetic Resonance Imaging(sMRI) scanning, followed by the assessment of Wechsler Adult Intelligence Scale (WAIS) and Schutte Self-Report Emotional Intelligence Scale (SSEIS). There are two kinds of index to measure one's cognitive intelligence: the standardized and raw scores of WAIS tests. The results of behavioral analysis showed that: there was no significant difference in the standardized scores of WAIS tests and emotional intelligence between the young adults and the middle-aged group; while in the raw scores of WAIS tests, the scores of fluid intelligence tests of the young adults are significantly higher than those of the middle-aged group. This result showed that the cognitive intelligence of individuals decreased with advancing aging, whereas there was no significant change in the score of emotional intelligence with advancing aging.
The study 2 was aimed to explore the associations of network efficiency with cognitive intelligence and emotional intelligence in young adults and the middle-aged group. We proposed a new method of defining the human brain morphological networks using the morphological distribution similarity (including cortical volume, surface area, and thickness). Our results showed inverted age X network efficiency interactions in the relationship of network efficiency with cognitive intelligence and emotional intelligence: a negative age X global efficiency (nodal efficiency) interaction in cognitive intelligence, while a positive age X global efficiency (nodal efficiency) interaction in emotional intelligence. We found that the significant age X network efficiency effect for cognitive intelligence in left temporoparietal junction, left superior parietal area, right ventromedial prefrontal area and right dorsolateral prefrontal area; while the significant age X network efficiency effect for emotional intelligence in the right sensory motor area, left temporal pole, left superior parietal area, left middle frontal gyrus and right cingulate gyrus.
In summary, study 1 and study 2 not only verified the developmental trajectory of cognitive intelligence and emotional intelligence, but also proposed a new method of morphological similarity network and emphasized the developmental effects on the
brain mechanisms of intelligence from young adult to middle-aged groups. This may promote mental health study on the middle-aged group and successful aging.