Social brain volume is associated with in-degree social network size among older adults

Abstract

The social brain hypothesis proposes that large neocortex size evolved to support cognitively demanding social interactions. Accordingly, previous studies have observed that larger orbitofrontal and amygdala structures predict the size of an individual's social network. However, it remains uncertain how an individual's social connectedness reported by other people is associated with the social brain volume. In this study, we found that a greater in-degree network size, a measure of social ties identified by a subject's social connections rather than by the subject, significantly correlated with a larger regional volume of the orbitofrontal cortex, dorsomedial prefrontal cortex and lingual gyrus. By contrast, out-degree size, which is based on an individual's self-perceived connectedness, showed no associations. Meta-analytic reverse inference further revealed that regional volume pattern of in-degree size was specifically involved in social inference ability. These findings were possible because our dataset contained the social networks of an entire village, i.e. a global network. The results suggest that the in-degree aspect of social network size not only confirms the previously reported brain correlates of the social network but also shows an association in brain regions involved in the ability to infer other people's minds. This study provides insight into understanding how the social brain is uniquely associated with sociocentric measures derived from a global network.

Cognitive resource allocation determines the organization of personal networks

“…As such, these are predictions of the model that could be tested. One is that an individual’s cognitive capacity [the ability to manage many relationships, which is a function of an individual’s brain size ( 17 , 38 , 39 ) or intellectual ability ( 40 ) or the time costs of investment in ties ( 28 , 41 )] is limited or because the available population is small (for geographical or, as in the case our immigrant samples, social reasons). Network size might also vary with personality differences.…”

Moderating effect of cognitive reserve on the association between grey matter atrophy and memory varies with age in older adults

“…The data from the CRAS ( n = 42) and those from the KSHAP ( n = 68) were pooled and a total of 110 participants with a mean age of 72.91 years (SD = 6.38,) and mean education of 6.77 years (SD = 3.90, range = 0–20) were finalised as the dataset (Table ). More detailed study procedures are noted in the previous literature . The study was approved by the Institutional Review Board of Seoul National University and Yonsei University.…”

Bridging the divide between biomedical and psychosocial approaches in dementia research: the 2019 INTERDEM manifesto

“…Emerging epidemiological evidence suggests that higher levels of social participation reduce occurrence and progression of cognitive impairment and dementia (Fratiglioni et al, 2004;Kuiper et al, 2015;Salinas et al, 2017). Social health factors can influence brain structure (Kwak, Joo, Youm, & Chey, 2018) and may contribute to brain reserve and enhance the plasticity of the brain (Fratiglioni & Wang, 2007). The brain reserve hypothesis refers to the capacity of the brain to resist the impact of brain pathology through plasticity that uses pre-existing cognitive processes or by activating compensatory approaches (Fratiglioni & Wang, 2007;Qiu & Fratiglioni, 2018).…”