It wasn’t possible to quantify the pruning delay or the difference in tissue density in this study, nor is it known whether those who had a greater density of tissue in the prefrontal cortex at this stage catch up with the rest of the population, at least to some extent, later, says Sahakian. “As you’re learning and your brain is getting more efficient, you get rid of the extra synapses you don’t want,” says Sahakian.
It is thought to happen because synapses – connections between brain cells – that aren’t used very much are lost. They are information messengers, using electrical impulses and chemical signals to transmit information between different regions of the brain and between the brain and the rest of the nervous system. Pruning is a mysterious process that starts in young childhood, although increases dramatically in adolescence. Neurons (or nerve cells) are the basic working units of the brain and nervous system. This, say the researchers, indicates a lack of, or delay in, pruning in their brains. People who had the highest scores for these conditions, indicating stronger symptoms, were more likely to have greater density of tissue in the prefrontal cortex, an outer region of the brain at the front of the head.
Brain scanning studies are usually too small to find reliable results
