Neuroscientists from the University of Cambridge analyzed nearly four thousand images of the brains of people aged from birth to 90 years to determine five fundamental developmental stages of the nervous system. Each of them is accompanied by an important turning point. And the first significant change in the brain occurs already at the age of nine.
According to the study, it takes almost three decades for the brain to reach its adult form. However, the first big turning point comes around the age of 9, when the brain enters the period known as adolescence. Until then, rapid consolidation of neural networks takes place: excess synapses disappear, only the most active ones survive. At the same time, the volume of gray and white matter, which ensures communication between areas of the brain, increases. Adolescence lasts approximately until the age of 32. During it, the biggest reorganization of the brain takes place.
“Efficiency in the brain is similar to how you would think about an efficient route between two places—it’s about getting the shortest, most direct path possible,” explains Dr. Alexa Mousley. It is this increasing efficiency that also leads to improved cognitive performance. At the same time, however, this is a period with a higher incidence of mental problems. “Many neurodevelopmental and neurological conditions are related to how the brain is wired,” says Professor Duncan Astle.
Between 32 and 66 years comes the longest and most stable stage – adulthood. The structure of the brain stabilizes and both personality and intelligence reach their long-term plateau. Around the age of 66, early aging begins. Brain connectivity gradually decreases and white matter begins to degrade. “At this age, the risk of health problems such as high blood pressure increases,” points out Dr. Mousley.
The last stage begins after the 83rd year of life. The brain loses more connections and becomes more dependent on certain areas. “Imagine that you normally take one bus to work. When this line is canceled, you have to take two. Similarly, when some connections in the brain weaken, other areas become more important,” the authors add.
