Scientists have found that in Down syndrome, the brain begins to develop with abnormalities while still in the womb. This discovery, made possible by the analysis of tens of thousands of cells, explains changes in its structure and cognitive functions.
Researchers from the University of California, Los Angeles, have made a breakthrough by creating one of the first detailed molecular maps of brain development in Down syndrome. Their work, published in the prestigious journal Science, provides insight into the process at the level of individual cells.
For this large-scale study, scientists meticulously analyzed over 100,000 cell nuclei. These samples were obtained from prenatal human neocortical tissue, representing the developing cortex of the fetal brain's cerebral hemispheres.
The material was collected from 26 donors at gestational ages ranging from 13 to 23 weeks, which is a critical period for the formation of all cortical neurons that will remain with a person for life.
Key Developmental Disruption
The main finding is that in Down syndrome, the sequence of brain development is severely disrupted. Precursor cells, which are the brain's stem cells, begin to differentiate into neurons much earlier than expected.
This leads to the depletion of their reserve, causing an imbalance between various types of neurons. For example, there is a noticeable increase in neurons of the upper layer of the intratelencephalic cortex and a decrease in neurons of the deep layer of the corticothalamocortical cortex.
New Understanding of Causes
Previously, it was believed that the smaller brain volume in individuals with Down syndrome was due to massive cell death. However, the new study convincingly disproves this hypothesis.
Now, the primary cause is considered to be the depletion of the precursor cell pool, which changes our understanding of the pathogenesis.
Broad Research Prospects
Furthermore, the scientists discovered a striking similarity in molecular disruptions in Down syndrome with genetic risk factors for other neuropsychiatric disorders. Among these are autism, epilepsy, and developmental delays.
This allows Down syndrome to be viewed as a valuable model for a deeper study of a wide range of similar conditions.
