The human brain is a marvel of complexity and capability, orchestrating everything from our physical movements to our innermost thoughts and emotions. As we age, this extraordinary organ undergoes a series of changes, some subtle and others more pronounced. While this may feel like a bad thing, it’s actually not. Our brain is designed to change across our lives and has the incredible capacity to do so. While of course the biggest changes happen in the first years of our life, the good news is that neuroplasticity continues well into late adulthood. While it’s impossible to identify the exact ages associated with brain development and changes, let’s explore the brain across the lifetime.
The infant brain
In infancy, the brain is incredibly dynamic. The cerebral cortex, responsible for perception and language, reaches its peak thickness at around age two. During these early years, the brain forms an immense number of synapses, making it highly receptive to learning from the environment. This rapid synaptic formation explains why infants can learn any language they are exposed to and why they soak up so much simply through observing the world around them. Iron deficiency can have significant consequences to the brain at this time, primarily due to its role in delivering oxygen to brain cells.
The childhood brain
From around ages two to ten, the brain undergoes significant changes. Synaptic pruning, where the brain eliminates excess connections, helps to streamline neural pathways, making them more efficient. This period also sees an increase in myelination, the process of insulating nerve fibres to speed up signal transmission. A range of nutrients and cholesterol are essential to myelination – myelin cannot actually be synthesised without cholesterol. Interactions with caregivers and the surrounding environment are crucial during this time, while distress or neglect can have a lasting impact on mental and emotional resilience. This is not to say that childhood needs to be idyllic, with zero complications or challenges – we cannot control everything that happens to us or our children during these formative years. Yet, providing a supportive and nurturing environment can make a profound difference. Without sounding like a broken record, iron deficiency is again the most common nutritional deficiency at this age and stage of brain development, which can lead to concerning consequences. A decreased attention span and learning problems are common symptoms, in part due to the brain not getting what it needs.
The adolescent brain
The teenage years, from about 10 to 19, are marked by dynamic changes in brain networks involved in emotion and motivation. Adolescents experience another wave of synaptic pruning and myelination, particularly in regions related to emotion and reward processing. This is a time when teens are more inclined to seek new experiences and test boundaries. Sex hormones also come online across this time which foster additional changes. Ovulation, for example, drives progesterone production, which has a calming effect on the nervous system. When menstruation first begins, ovulation is not common though – it takes a while for this to start occurring cyclically (you can have a period without ovulation at any age) so calm might not be on offer for a time after menarche. In boys, when testosterone increases, brain changes can lead to more risk-taking behaviour under the guise that they’ll be fine in any instance. Zinc is a key nutrient for girls and boys at this time for good brain health.
The young adult brain
The mid-to-late 20s are often thought of as a peak period for brain development. White matter volume, indicative of the brain’s processing speed, reaches a high level during these years. While quick, sharp processing may eventually decline, rest assured neuronal networks continue to refine, particularly those involved in rational thought, strategic thinking and future planning.
The midlife brain
In midlife, the years around 40-65, the brain’s plasticity continues to evolve. New research has shown that “silent synapses,” previously thought to be limited to early development, are also present in adult brains. These synapses can be recruited to help form new memories, indicating that the brain retains significant capacity for change. Experiences such as social engagement, lifestyle choices, and exposure to stress or toxins can greatly influence brain health. A socially active, physically fit 54-year-old may have a more youthful brain compared to a sedentary, isolated counterpart.
The later adulthood brain
In the later years, the brain does tend to shrink and some degeneration occurs. However, older adults also possess the potential for greater wisdom, derived from a lifetime of experiences. Emotional processing and moral decision-making capabilities may enhance, contributing to what we often refer to as wisdom. Engaging in memory training, puzzles, and enriching, meaningful activities can help maintain cognitive functions. Two useful questions to ponder that can support brain health at all ages and stages are “what I am learning?” and “what am I creating?” A curiosity for learning has been shown to continuously promote neuroplasticity and life satisfaction. Creating anything from a new dinner meal to a painting, activates a different neural circuit which includes the neural plexus around the heart. Is it possible that contributes to why we can feel a deep sense of satisfaction or even life purpose when we create?
What makes the brain age prematurely?
While ageing is a natural process, certain factors can accelerate the ageing of the brain, leading to cognitive decline earlier than expected. Chronic stress, a lack of nutrients or a diet predominantly comprised of ultra processed foods/high in refined sugars, sedentary lifestyle, sleep deprivation, substance abuse, social isolation, smoking and chronic diseases all contribute to premature ageing throughout the body – including the brain.
This blog was inspired by these two pieces of work:
Brain charts for the human lifespan: https://www.nature.com/articles/s41586-022-04554-y and How does the brain age across the lifespan? New studies offer clues: https://www.washingtonpost.com/wellness/2023/02/28/brain-aging-childhood-teens-adults/
