Autism is the Trojan Horse of the gift of speech, according to Yale neurobiologist Nenad Sestan, “The same evolutionary mechanisms that may have gifted our species with amazing cognitive abilities have also made us more susceptible to psychiatric disorders such as autism.”
In a recently published paper in the journal Cell, Sestan and his team traced the evolutionary changes that occurred in activation of the NOS1 gene that takes charge of developing the parts of kid’s brains that form the adult centers for speech, language and decision-making. This sequence is activated by the FMRP protein. But if an X chromosome goes bad, no protein is produced. Without the protein, no gene activation. This is known in the trade as the Fragile X syndrome. Fragile X Syndrome is the number one single-gene cause of autism and mental retardation.
The loss of NOS1 activity may contribute to many of the cognitive deficits suffered by those with Fragile X syndrome, such as lower IQ, attention deficits, and speech and language delays, the authors say,” according to Science Daily.
This NOS1 activation pattern does not occur in mice, despite all their yodeling, so the researchers think that the adaptation occurred more recently in mammalian history, possibly when natural selection was rewiring human brain circuits for high-powered cognitive abilities like speech. The research has also lead to further insights into how genetic problems affect early brain development that lead to autism and similar disorders that appear shortly after birth.
“This is an example of where the function of genetic changes that likely drove aspects of human brain evolution was disrupted in disease, possibly reverting some of our newly acquired cognitive abilities and thus contributing to a psychiatric outcome,” said Kenneth Kwan, one of the researchers.
“Most boys with Fragile X have some problems with speech and language. They may have trouble speaking clearly, or may stutter, or leave out parts of their words. They may also have problems understanding “clues” when talking to other people, such as understanding the speaker’s tone of voice or that person’s body language. Girls usually do not have severe problems with speech or language,” but many people with Fragile X have intellectual disabilities, difficulties socializing and problems with certain sensations such as bright lights and sadly, human touch.
Unfortunately, there is still no cure for this genetic condition, although recent clinical trials have been encouraging. So far the best treatment remains lots of attention and understanding.