Scientists have potentially confirmed a theory about the origins of autism by creating miniature, 3D replicas of human brains. These tiny brains, derived from the stem cells of toddlers, were grown to simulate the development of these children’s brains in the womb. The new study, published on May 25th in the journal ‘Nature,’ involved drawing stem cells from the blood of 10 toddlers diagnosed with autism and six toddlers without the disorder. These toddlers were between 1 and 2 years old at the time of the study. Utilizing growth-inducing chemicals, the researchers cultivated “brain organoids” from these stem cells in the laboratory. As these organoids grew, they accurately replicated key aspects of human brain development and function during pregnancy. Since each organoid was derived from a toddler’s own tissue, it could be considered a mini version of that child’s brain during pregnancy, as if the scientists had reversed the developmental clock.
The researchers diligently tracked changes in the size and growth of these organoids during the early stages of embryonic development. They also assessed the severity of each toddler’s current autism symptoms, including their ability to focus attention, communicate with others, their language skills, and their IQ. Additionally, the team conducted scans of the toddlers’ actual brains to analyze the activity of different cells, particularly those in brain regions linked to social skills and language.
The team observed a significant finding: the brain organoids of toddlers with autism grew nearly three times faster than those of toddlers without autism. These organoids became significantly enlarged by around 40% between the first and second month of pregnancy, compared to the control group. This trend was consistent: the larger the brain organoid, the more severe the social symptoms of autism were in the corresponding toddler.
Previous studies, conducted by the same research team, had connected increased brain size in the early years of life to the severity of social symptoms in individuals with autism. However, this latest research provides a direct link between symptom severity and brain size in individual toddlers, rather than highlighting trends within a group.
Dr. [Name], a professor of child and adolescent psychiatry at the University of Manchester in the U.K., who was not involved in the study, commented, “These new findings add interestingly to their [the study authors’] previous work.” The new research suggests a “quantitative association” between the degree of brain overgrowth observed in the womb and the degree of later autism symptoms, Green explained in an email to Live Science. The results could “potentially add to our knowledge about neural aspects of autism.” He added, “It will be very interesting to see if these findings can be replicated by others.”
In a separate experiment conducted as part of the same study, the researchers discovered that a higher growth rate and larger size of the brain organoids in toddlers with autism were correlated with increased activity in a gene called Ndel1. This gene codes for a protein that assists in [function of the protein], leading the scientists to conclude that dysfunction in Ndel1 likely contributes to the excessive brain growth observed in autism. “Determining that NDEL1 was not functioning properly was a key discovery,” said [Name], co-senior study author and a professor of pediatrics at the University of California, San Diego, in a statement.
Although the study included only 16 toddlers, making it relatively small, this type of research is “incredibly laborious and expensive.” Therefore, this dataset is considered “pretty impressive” according to [Name], a reader in developmental neuroscience at King’s College London, who was not involved in the research.
It’s important to note that social symptoms are not the only component of autism. Many individuals with the condition may experience other challenges such as repetitive behaviors, delayed movement skills, and anxiety, which were not assessed in this new study. This limitation may affect how well the findings generalize to a broader population.
Looking forward, the research team aims to identify additional genes that could be driving excessive brain growth in autism. They aspire to use this knowledge to develop new therapies for the disorder in the future.
