Socioeconomic status affects children’s brains
Socioeconomic status (SES) appears to influence brain morphology in children, particularly regarding global cortical and subcortical volumes and surface area, according to a new study.
“Our findings inform ongoing efforts to clarify the spatiotemporal patterning of SES-related neuroanatomical variation and its relation to cognitive outcomes such as IQ,” said researchers, emphasizing the role of SES as a complex construct that affects the psychosocial developmental environment of a child.
In the present study, the investigators assessed a longitudinal sample of 1,243 structural magnetic resonance imaging brain scans from 623 healthy children and adolescents (mean age at first scan 12.0±4.0 years; 324 males). The mean cohort IQ at baseline was 114±12.4, while the mean Hollingshead SES index score was 41.2±18.3. [J Neurosci 2018;doi:10.1523/JNEUROSCI.1808-18.2018]
A strong, positive and significant correlation was observed between SES and total brain volume (p<0.001), white (p<0.001) and gray (p<0.001) matter volume, and volume of the cortical sheet (p<0.001). The same was true for total cortical surface area (p<0.001) and mean thickness (p=0.01).
A similar trend was observed between SES and all subcortical volumes–hippocampus (p=0.001), amygdala (p=0.018), thalamus (p<0.001) and striatum (p=0.042)–except for the pallidum (p=0.21).
Vertex-level analyses further showed that the relationship between SES and cortical surface area could be localized to a set of bilateral cortical areas including the superior parietal lobule, lateral temporal, anterior cingulate and lateral prefrontal regions. The correlation between SES and cortical thickness was much less distributed and was localized singly in the right supramarginal gyrus.
“We extend analyses of SES associations with subcortical anatomy to provide the first evidence that greater childhood SES is associated with larger bilateral volumes of the thalamus and striatum. The thalamic finding is especially notable given reported associations between thalamic volume and cognitive performance,” said researchers. [Cogn Brain Res 2001;11:377-385]
“Definition of these neuroanatomical associations may ultimately provide candidate biological substrates against which to test potential mechanistic pathways between SES and cognitive and health outcomes,” they added.
Moreover, researchers pointed out that with the exception of hippocampal volume, the interaction between SES and brain morphology remains stable between the ages of 5 and 25 years. This suggests that this interaction may change over time, with a dynamic relationship taking place in early life followed by a period of stabilization.
In a subsequent structure-function analysis, the effects of SES on brain morphology were generally concentrated on regions associated with emotional processing, memory, language and sensorimotor functions.
However, it is important to note that “the results presented here do not establish a direct causal pathway between SES and brain development, nor do they indicate that childhood SES exerts a deterministic effect on development,” said researchers.
“Rather, by resolving neuroanatomical substrates that vary closely with SES, we contribute new biological information to a growing field of multidisciplinary research that ultimately aims to reduce SES variation in health and achievement,” they added.