Early home environment, especially the level of cognitive stimulation such as the number of books and educational toys in the home, at age 4, predicted the efficiency of cognitive pruning in the lateral inferior temporal gyrus and another part of the cerebral cortex in the left temporal region at late adolescence (age 16-18). The lateral inferior temporal gyrus is involved in word recognition. A better pruned region will be thinner yet more efficient.
The level of cognitive stimulation at age 8 also had an effect at age 16-18, but less of one.
The mother’s level of intelligence and the degree and quality of her care had no effect on the development of these regions, so we can rule out selection bias and a genetic effect whereby smarter mothers provide a more stimulating environment for their children coincidentally hence a genetic effect masks as an environmental one.
Previous research showed that childhood abuse, neglect and poverty actually stunts the brain.
Early home environment in terms of a cognitively stimulating environment has positive effects on brain development all the way up to near adulthood.
Take that, HBD’ers!