We tend to think of brain ageing as a single, inevitable decline, like a battery slowly running down. Memory fades, processing slows, and eventually, everything becomes a bit harder. But new research reveals something far more interesting: your brain doesn't age uniformly. Different regions decline at different rates, in a specific order, and understanding that sequence matters.
The question isn't just "is my brain ageing?" It's "which parts are ageing first, and what can I do about it?"
The frontal lobe goes first
The prefrontal cortex (the brain region responsible for executive function, decision-making, planning, and impulse control) is one of the earliest and most vulnerable areas to show age-related decline.
This matters because the prefrontal cortex is what allows you to:
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Focus on complex tasks without getting distracted
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Switch between different activities efficiently
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Plan ahead and think through consequences
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Control emotional reactions and resist immediate temptations
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Hold multiple pieces of information in working memory
These are the skills that keep you sharp, capable, and adaptable. And they're also the first to show subtle decline, often starting in your late twenties or early thirties.
You might notice this as:
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Taking longer to learn new systems or processes
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Feeling more mentally fatigued after complex problem-solving
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Finding it harder to multitask effectively
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Struggling more with distractions or maintaining focus
Memory systems decline unevenly
Episodic memory (your ability to recall specific events, conversations, or experiences) tends to decline earlier and more noticeably than other types of memory. This is the kind of memory that makes you forget where you left your keys, what you ate for breakfast yesterday, or the name of someone you met last week.
Semantic memory (your general knowledge about the world, facts, concepts, and vocabulary) remains relatively stable much longer. This is why older adults often retain deep expertise in their fields and can recall historical events or cultural references with clarity, even when they struggle with recent personal details.
Procedural memory (the kind that governs skills like riding a bike, typing, or playing an instrument) is remarkably resistant to ageing. Once learned, these motor and cognitive routines remain encoded in brain regions that show slower decline.
The hippocampus, which is critical for forming new episodic memories, is particularly vulnerable. It shrinks with age, and its connectivity with other brain regions weakens. This is why "senior moments" often involve forgetting recent information rather than losing long-established knowledge.
Processing speed slows down
One of the most consistent findings in ageing research is that cognitive processing speed declines gradually but steadily from early adulthood onward.
This doesn't mean you become less intelligent or capable. It means the rate at which you process information, make decisions, and respond to stimuli slows down incrementally over decades.
Processing speed affects:
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Reaction time in situations requiring quick decisions
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How quickly you can learn and integrate new information
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Mental flexibility when adapting to unexpected changes
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The effort required to keep up with fast-paced conversations or environments
Interestingly, while raw processing speed declines, accumulated knowledge and experience can compensate. Older adults often make better decisions in complex, real-world situations because they draw on patterns and insights built over decades. Speed isn't everything.
Some regions stay remarkably stable
We’ve got some good news as well: some brain regions remain surprisingly stable well into late life.
The primary sensory and motor cortices, areas responsible for basic sensory processing and movement control, show relatively little age-related decline until very late in life. This is why coordination, balance, and sensory perception can remain sharp even when memory and executive function start to slip.
The emotional regulation systems, particularly areas involved in processing positive emotions and managing stress, often improve with age. Older adults tend to experience fewer negative emotions, better emotional control, and greater overall life satisfaction compared to younger adults. This isn't just wisdom, it's partly structural. Brain regions involved in emotional regulation become more efficient and better integrated over time.
Why does the brain age in layers?
The pattern of brain ageing isn't random. It reflects fundamental principles of neurobiology.
Brain regions that develop latest in childhood tend to decline earliest in ageing. The prefrontal cortex is one of the last areas to fully mature - it doesn't finish developing until the mid-twenties. This late maturation makes it more vulnerable to the cumulative effects of metabolic stress, oxidative damage, and cellular ageing.
Brain regions with high metabolic demands are also more vulnerable. The prefrontal cortex and hippocampus are metabolically expensive to maintain. They require constant energy, generate more oxidative stress, and accumulate cellular damage faster than less active regions.
Areas with rich connectivity, regions that communicate extensively with other parts of the brain, face greater risk. More connections mean more potential points of failure as synapses weaken and white matter degrades.
What can you do about it?
The good news is that the brain is remarkably plastic, even in older age. While you can't stop ageing entirely, you can influence how different regions hold up over time.
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Cognitive engagement: Activities that challenge executive function, like learning new skills, solving complex problems, engaging in strategic games, help maintain prefrontal cortex function.
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Physical exercise: Aerobic exercise increases blood flow to the brain, promotes neurogenesis in the hippocampus, and supports white matter integrity. It's one of the most effective interventions for slowing cognitive decline.
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Sleep quality: Deep sleep is when the brain clears metabolic waste, consolidates memories, and repairs cellular damage. Chronic sleep deprivation accelerates cognitive ageing, particularly in the prefrontal cortex.
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Stress management: Chronic stress damages the hippocampus and accelerates prefrontal decline. Practices that reduce stress, like meditation, time in nature, social connection, have measurable protective effects.
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Metabolic health: Inflammation control and cardiovascular health all directly impact brain ageing. What's good for your heart is good for your brain.
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Social engagement: Meaningful social interaction stimulates multiple brain systems simultaneously. Loneliness and social isolation accelerate cognitive decline, while strong relationships appear to buffer against it.
Ageless NMN
Cellular energy production is fundamental to brain function, and NAD+ is at the centre of that process. NAD+ is a coenzyme involved in energy metabolism, DNA repair, and cellular maintenance - all processes that decline with age and contribute to cognitive ageing.
Ageless NMN provides nicotinamide mononucleotide, a direct precursor to NAD+, supporting the cellular pathways that help maintain brain function over time. While it's not a magic solution, Ageless NMN is designed to work alongside the lifestyle factors that matter most: exercise, sleep, mental engagement, and metabolic health.
Brain ageing happens in layers. Supporting it requires the same approach - layered, consistent, and targeted at the systems that matter most.
