Socio-economic status, executive functions, and theory of mind ability in adolescents: Relationships with language ability and cortisol.

Socio-economic status (SES) is linked to the development of cognitive abilities, particularly language and executive processes. It is unclear whether these represent a single or independent correlates. We studied 110 Ecuadorian youths aged 12-17 with measures of SES, language, executive function, and theory of mind (ToM), a.k.a. mentalizing. A subsample gave hair samples to estimate recent cortisol levels. Restricting analyses to reliable measures, SES was highly associated with language skill, and to a lesser extent with executive function and ToM performance. However, those latter associations were attenuated and non-significant when language ability was controlled for statistically. Systemic cortisol levels were not associated with SES, but were significantly and negatively correlated with ToM, independent of variation in language skills. We conclude that language development underlies most of the impact of SES on executive function and ToM ability of adolescents, but that stress-related cortisol may have an independent, direct effect on mentalizing.

Socioeconomic deprivation and the development of neuropsychological functions: A study with "street children" in Ecuador.

Socioeconomic status (SES) is known to have a considerable influence on the development of neuropsychological functions. In particular there is strong evidence for less efficient development of prefrontal-cortex-related functions in children raised in low-SES households. "Street children" are a common feature of low SES in many low- and middle-income countries, and some researchers have suggested that the unique life experiences of street children may drive their neurocognitive development. This study compares a group of 36 former street children in Quito, Ecuador with a control group of 26 never street-connected schoolchildren. All children were assessed with a range of neuropsychological tests. Although the street children group performed significantly below the level of the control group on all measures, they did not demonstrate a generalized lower ability. By controlling the effects of fluid intelligence it was found that there are relatively independent effects on visuospatial ability and executive planning ability. Furthermore, the executive function test scores in general are significantly less affected than the other cognitive functions and may be temporary effects caused by recent substance abuse within the street child sample. The findings generally support results from other countries suggesting that low SES is associated with negative effects on neuropsychological development. However, they also suggest that the local social and economic context, such as in the case of street children, might mitigate the harmful effects of low SES on the development of some executive functions.