Brain Scans Show Ages Two To Four As "Critical Window" For Language Development

For many parents, the ages from two to four represent a challenge. This is the stage of budding independence, tantrums, and the ideal time to practice saying "no". Scientists suggest that the crucial window for language development also falls within this age group, which means that language delays should be addressed during this time. 

The brain's wiring develops to process new words before the age of four, new research published in the Journal of Neuroscience suggests. That means environmental factors have the biggest impact before a child reaches four, explains why young kids can easily become bilingual, and stresses the importance of seeking help if a child has language delays. 

What The Brain Scans Show

Researchers from King's College London and Brown University, Rhode Island, studied 108 children between the ages of one and six. All showed normal brain development. The team looked at myelin, the insulation that develops within the circuitry of the brain from the time a baby is born, and reached the conclusion that its distribution becomes fixed once a child reaches age four. 

Twelve-month old babies have tend to have a vocabulary of around 50 words. After that age, kids are constantly acquiring new words until they have a vocabulary of approximately 5,000 words at age six. 

The brain's "language-skills area" sits in the frontal areas of the left side, and the research team was expecting more myelin to accumulate there over time, as children's vocabulary increased. The fact that the brain scans these scientists carried out show that this didn't happen and that myelin actually stays the same after age four is a really important finding, then.

Dr Sean Deoni from Brown University, a co-researcher on the study explains why his team's work matters: "This work is important as it is the first to investigate the relationship between brain structure and language across early childhood and demonstrate how this relationship changes with age." He added:

The study's lead author, Dr Jonathan O'Muircheartaigh from King's College London, had more to say about how these findings can be used to help children in practice. He told the BBC: "Since our work seems to indicate that brain circuits associated with language are more flexible before the age of four, early intervention for children with delayed language attainment should be initiated before this critical age."

He pointed out that his team's research can be relevant to a large number of developmental disorders including autism. Delayed language is a common trait among children with these disorders, but there is no reason to believe the critical age window doesn't also apply to other cognitive skills. 

What does this mean for parents of young children? The research can clearly benefit kids with language delays, but it can also be applied to help neurotypical children get the most out of their early childhood.