Scientists have spent many years trying to understand brain disorders such as autism, schizophrenia, and Alzheimer’s disease.
These conditions affect millions of people around the world and can change how a person thinks, learns, communicates, and behaves.
Although researchers have identified many genes and brain changes linked to these disorders, there is still much to learn about how the brain develops and functions.
One area that has attracted growing interest is a protein called IDO2. Until now, scientists knew very little about what this protein does in the brain.
A new study led by Associate Professor Yasuko Yamamoto in Japan has now suggested that IDO2 may play an important role in healthy brain development and social behaviour. The findings were published in a scientific journal and provide a new direction for future autism research.
IDO2 is involved in breaking down tryptophan, an amino acid found in foods such as meat, eggs, milk, cheese, and other dairy products.
When the body processes tryptophan, it creates several natural chemicals through a series of reactions known as the tryptophan-kynurenine pathway. Earlier research suggested that some of these chemicals may influence mental health, but the exact role of IDO2 remained unclear.
To investigate further, the researchers created specially bred mice that did not have the IDO2 gene. These animals, known as knock-out mice, allowed the scientists to observe what happened when the protein was missing. They then compared these mice with healthy mice that had normal levels of IDO2.
The differences were striking. Mice without IDO2 found it difficult to adapt to new situations and repeatedly groomed themselves for long periods.
They also showed little interest in exploring their surroundings and had trouble learning by watching other mice. These behaviours resemble some features commonly seen in autism, although animal studies cannot fully represent the condition in people.
When the team examined the animals’ brains, they found important chemical changes. Without IDO2, the normal processing of tryptophan was disrupted, leading to abnormal dopamine levels in parts of the brain such as the striatum and amygdala.
Dopamine is a chemical messenger that helps control movement, motivation, learning, and emotions, so changes in its levels could explain many of the behavioural differences.
The researchers also discovered lower levels of brain-derived neurotrophic factor, or BDNF. This important molecule helps brain cells grow, survive, and build strong connections with one another. In the mice lacking IDO2, brain cells formed fewer mature connections and more immature ones, suggesting that brain development had been affected.
Another finding involved microglia, the brain’s immune cells. These cells normally protect the brain by removing damaged cells and helping maintain healthy tissue. In the IDO2-deficient mice, however, the microglia became much more active than usual. The researchers believe this increased activity may have contributed to the changes seen in brain function and behaviour.
Perhaps the most encouraging result came when the scientists restored the missing IDO2 gene in the mice. After the gene was returned, many of the animals’ unusual behaviours became less severe, showing that IDO2 itself plays an important role.
The team also examined brain samples from more than 300 people with autism and found one teenage girl carrying a mutation in the IDO2 gene. While this does not prove that IDO2 causes autism, it strengthens the idea that the protein deserves much more study.
Much more research will be needed before these findings can lead to new treatments for people. However, the study offers an exciting new clue about how brain chemistry may influence learning, emotions, and social behaviour.
By understanding proteins such as IDO2, scientists hope to develop better ways to diagnose, prevent, and treat autism and other brain disorders in the future.
If you care about autism, please read studies about a new cause of autism, and cats may help decrease anxiety for kids with autism.
For more information about health, please see recent studies about vitamin D that may hold the clue to more autism, and results showing strange eating habits may signal autism.
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