Adolescence does not stop at age 18: a study published in the scientific journal Nature Communications now offers a new life picture of the human brain. According to the researchers, the human brain goes through five different “ages”, which last from childhood to late old age. The findings, gathered from an analysis of approximately 3,800 MRI scans of babies up to ninety years old, indicate deep structural trends in neural networks, and reveal precise turning points during life.
According to the findings, the first era of the brain’s life stages lasts from birth to age 9. During these years, an accelerated growth of gray and white matter occurs, while the neural pathways are reorganized. This is a period when the brain is forming at a rapid pace, acquiring basic abilities and reformulating the way information is processed.
The second age, between the ages of 9 and 32, is the longest and most surprising. The researchers found that it is the only time when brain networks continue to become more efficient, with fast and wide communication between distant regions. This is a period that is also considered to be significantly sensitive in terms of mental health. Most psychiatric disorders appear in it, and the researchers wonder if there is something in the redesign of the networks that increases the brain’s vulnerability to depression, anxiety and other disorders.
The third age, from age 32 to 66, is characterized by relative stability. The brain still undergoes changes, but they are slower and more moderate. This is a time when people are generally seen as having reached a balance in terms of intelligence, emotional control and personality traits.
From the age of 66 to 83, a new process begins. The brain has become “modular”, meaning it is built more of independent sub-networks and less of a central connection than one. Communication between distant areas weakens, and the brain makes use of short, local paths. At age 83, according to the study, another turning point comes, when brain connectivity continues to decline significantly.
The research was based on a technology called diffusion MRI, which monitors the movement of water molecules in the brain and thus allows to map nerve pathways wrapped in a layer called “myelin”. The researchers used nine different scan databases that were combined into one broad model, creating the largest cluster of its kind. The goal was to identify how brain networks strengthen, weaken or change over time.
“The concept that the brain goes through five stages throughout life emphasizes how dynamic and flexible it is,” explains Dr. Lior Unger, deputy director of the neurosurgery department at the Sheba Medical Center, “it is possible that in the future we will be able to use this division to identify medical conditions earlier and direct treatments more precisely. We are just beginning to understand the rhythm of life of the human brain, and this research sets a significant milestone on this path.”