A groundbreaking systematic review conducted by researchers from Monash University in Australia has shed light on the fascinating changes that occur in the human brain as we age. The study, published in the journal Psychophysiology, analysed 144 studies and tens of thousands of brain scans to uncover the intricate process of brain rewiring that takes place during our lifetime.

Traditionally, the brain has been viewed as a complex network consisting of interconnected regions and neurones. However, this study reveals that as we enter our fifth decade of life, the brain undergoes a radical transformation, resulting in a rewiring of its networks. These networks become more integrated and connected, leading to significant effects on cognition.

During our teenage and young adult years, the brain exhibits numerous partitioned networks with high levels of inner connectivity. This reflects the brain’s ability to engage in specialised processing, allowing us to learn new skills and develop talents. However, around the age of 40, a shift occurs. The brain begins to exhibit less connectivity within these separate networks and instead becomes more globally connected across networks. By the time we reach our 80s, the brain tends to be less regionally specialised and more broadly connected and integrated.

This rewiring process has tangible effects on cognition. Older adults often exhibit less flexible thinking, reduced response inhibition, and lower verbal and numeric reasoning abilities. These changes in executive function typically emerge in individuals during their fifth decade of life, aligning with the findings of this systematic review, which indicates that functional network connectivity changes reach their inflection point in the fourth and fifth decade.

However, it’s not all bad news for the aging brain. Tasks that rely on automatic or well-practiced processes, such as vocabulary and general knowledge, are less impacted by age and may even improve slightly across the lifespan.

But why does this rewiring of the brain occur in the first place? The researchers offer some intriguing speculation. The brain is a highly resource-intensive organ, requiring a significant amount of glucose to function optimally. In fact, despite accounting for only 2% of total body weight, the brain consumes around 20% of the body’s glucose supply. As we age, our bodies naturally slow down, and the brain becomes less efficient in utilising glucose. This decline in glucose availability and efficiency likely triggers the brain to reorganize itself, optimising its function with limited resources and aging “hardware.”

Fortunately, there are steps we can take to support our brain health and delay these networking changes. A proper diet, regular exercise, and a healthy lifestyle can help keep the mind in good working order and potentially slow down the rewiring process, allowing us to maintain cognitive function well into old age.

The inner workings of the brain remain a mystery, but this comprehensive systematic review, encompassing hundreds of studies and tens of thousands of brain scans, provides us with a glimpse into the changes that occur across our lifetimes. The researchers conclude that during the early years of life, there is a rapid organisation of functional brain networks, followed by further refinement until the third and fourth decade of life. As we age, a complex interplay of potentially harmful and compensatory changes takes place.

This groundbreaking research not only deepens our understanding of the brain’s remarkable adaptability but also highlights the importance of maintaining a healthy lifestyle to support optimal brain function as we age. By embracing healthy habits, we can potentially delay the rewiring process and enjoy a sharper mind for longer.