What actually happens to the brain as we grow older?
Short answer
The ageing brain is changing, not simply declining.
The Main Findings:
- Not everything declines with age. Some abilities become slower or more vulnerable, while others remain relatively strong.
- Different parts of the brain age differently. There is no single pattern of decline happening everywhere at once.
- People age differently too. Two people of the same age can have very different cognitive abilities and patterns of brain ageing.
- Slower doesn’t mean incapable. Learning may take more time or repetition, but the ability to learn remains.
- The brain keeps responding to experience. Even later in life, it can continue to learn, adapt and change.
What the Research Shows
The ageing brain can be getting slower and still be capable of learning something entirely new.
Some areas gradually shrink, communication can become less efficient, and processing speed, working memory and some forms of memory may become slower.
But these changes vary across the brain and from person to person. Some abilities remain relatively strong, and the brain can still learn, adapt and find new ways to get things done.
1. The brain gradually changes in structure
MRI research gives us a fascinating look at how the brain changes as we grow older.
Anna Hedman and colleagues reviewed 56 long-term MRI studies involving more than 2,200 people. They found that brain volume gradually decreases through adulthood, with the rate of change tending to increase later in life.
But the whole brain doesn’t change in the same way. Some areas are more affected than others.
That’s an important part of understanding brain ageing:
Different parts of the brain change in different ways and at different rates.
2. The connections between brain regions change too
A review of 36 studies involving more than 19,000 people found that changes in the brain’s white matter were linked with a higher risk of cognitive decline and dementia.
A more recent analysis found something similar: changes in the brain’s small blood vessels were associated with small declines in memory, attention and thinking skills.
Why does this matter?
Different parts of the brain need to communicate with each other. Much of that communication travels through white matter, the nerve fibres that connect different brain regions.
As we get older, these connections can become more vulnerable, partly because of changes in the small blood vessels that supply the brain.
This doesn’t tell us what will happen to any one person. But it does reinforce an important connection: Looking after our vascular health is also part of looking after our brain health.
3. Processing speed often becomes slower
Psychologist Timothy Salthouse’s research found that processing speed often slows with age, and this may affect other areas of thinking. When it takes a little longer to process information, complex tasks can become harder, especially when we need to think quickly, remember several things at once or move from one step to the next.
But slower doesn’t mean less capable. Taking longer to process something doesn’t mean losing the ability to think, learn or make good decisions. You may need more time to learn new technology at 75 than you did at 35. But you can still learn it.
4. Some forms of memory become more vulnerable
Research shows that memory doesn’t change in one simple way as we get older.
Remembering particular events and experiences can become harder. So can working memory, holding information in mind while we use it.
That may be why a familiar name sometimes takes longer to arrive, or why keeping several pieces of new information in mind feels more difficult. But this doesn’t mean our memory is simply disappearing. Some forms of memory remain relatively strong, and everyone ages differently.
Some things may take longer to remember, but the capacity to remember and learn remains.
5. The ageing brain may change how it gets things done
Brain scans show that older and younger adults sometimes use their brains differently to do the same task.
Older adults may bring additional brain regions into play. Researchers call one explanation for this the Scaffolding Theory of Aging and Cognition: as some parts of the brain become less efficient, others may help support the task.
But more brain activity doesn’t always mean the brain is compensating successfully. Sometimes it may simply be working harder. Researchers are still trying to understand when this happens and why. But the larger idea is intriguing: the ageing brain may sometimes find different ways to get things done.
6. The brain can still change
A review of 20 cognitive-training studies found that older adults could still improve the abilities they practised. Some studies also found changes in brain structure, although the effects didn’t always extend to other abilities.
Research from the Synapse Project and ACTIVE trial tells a similar story: older adults can still learn and improve with practice.
That doesn’t mean the ageing brain is untouched by time—or that we can completely “rewire” it at any age.
The evidence tells a more balanced story:
The brain changes as we grow older, but it doesn’t stop learning and adapting.
7. Brain ageing varies enormously between people
Long-term studies show that two people of the same age can have very different ageing brains.
Some people experience more changes in memory, thinking or brain structure than others. Genetics, health, education, life experiences, physical activity and social connection can all play a part.
So age only tells us part of the story.
Knowing someone is 70 doesn’t tell us how well their brain is functioning, or what it may still be capable of. There is no single way a 70-year-old brain is supposed to be.
What the research suggests
Decades of research tell us that the brain changes as we get older, but it doesn’t simply decline.
Some areas shrink, connections can become less efficient, and we may take longer to process information or remember certain things. But these changes vary enormously from person to person.
You might take longer to remember a name or learn new technology, while your knowledge, vocabulary and experience remain strong.
And importantly, the brain can still change. Older adults can continue to learn and improve with practice, sometimes with measurable changes in how the brain works.
The improvements are usually strongest in what we actually practise. Learning one skill doesn’t suddenly improve everything or completely “rewire” the brain.
The picture is much more interesting than simple decline:
Some abilities become more vulnerable. Others remain strong. And the brain keeps learning and adapting.
What the research cannot tell us
Research can show us what commonly happens as the brain ages, but it can’t tell us exactly what will happen to you. Forgetting a name or taking longer to learn something new can be part of getting older. But we shouldn’t assume every change is “just age.”
Normal ageing and dementia aren’t the same thing. Some slowing and memory changes can happen with age. Dementia involves more significant changes that begin to affect everyday life.
Brain scans only tell part of the story too. Two people can show similar changes in the brain and function very differently in daily life.
So research gives us patterns, not predictions. A changing brain doesn’t automatically mean a less capable brain.
Evidence confidence: High
The evidence is strong that our brains change as we age while retaining the ability to learn and adapt.
What research can’t tell us is exactly how any one person’s brain will age—or that any particular activity can prevent or reverse brain ageing. We can influence some of the conditions around brain ageing, but we can’t completely control it.
What this means for everyday life
Our brains change throughout life. So rather than trying to stop that, a more useful question might be: How can I work with the brain I have now?
Maybe you need more time, more repetition, better sleep, fewer distractions or a different way of learning.
The point isn’t to pretend ageing changes nothing. It’s to notice what has changed without deciding that change means you’re no longer capable.
Longevity Reimagined reflection
There’s an important difference between: “My brain is changing.” and: “My brain can no longer change.”
Research shows that neuroplasticity continues into older age. Older adults can still learn new skills, improve specific abilities through practice and show measurable changes in how the brain works.
Learning may take more time or repetition, but the brain hasn’t lost its ability to adapt.
So when something feels harder, instead of thinking I’m too old for this, we might ask: Do I need more time, more practice or a different way of learning?
Ageing changes the brain. But it doesn’t stop the brain from changing.
Core research references
Taken together, these studies support a careful but encouraging conclusion: ageing brings measurable changes in brain structure, white matter, processing speed and some cognitive abilities. Those changes are real, but they are highly variable and do not amount to a simple, uniform decline. At the same time, the older brain retains a meaningful capacity for learning and neuroplasticity. (PubMed)
- Hedman, A. M., van Haren, N. E. M., Schnack, H. G., Kahn, R. S., & Hulshoff Pol, H. E. (2012). Human brain changes across the life span: A review of 56 longitudinal magnetic resonance imaging studies. Human Brain Mapping, 33(8), 1987–2002. DOI: 10.1002/hbm.21334.
This is an excellent foundation for the section on structural brain ageing. It brought together 56 longitudinal MRI studies involving 2,211 people aged 4–88 at their first scan and found continuing changes in whole-brain volume across the lifespan, with volume loss generally accelerating in later adulthood. (PubMed)
View the study on PubMed - Oschwald, J., Guye, S., Liem, F., Rast, P., Willis, S., Röcke, C., Jäncke, L., Martin, M., & Mérillat, S. (2020). Brain structure and cognitive ability in healthy aging: A review on longitudinal correlated change. Reviews in the Neurosciences, 31(1), 1–57. DOI: 10.1515/revneuro-2018-0096.
Particularly useful for explaining that changes seen in the brain do not map neatly onto changes in thinking ability. The review examined 31 longitudinal studies and highlights how complex and variable the relationship between structural and cognitive ageing is. (PubMed)
View the study on PubMed - Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103(3), 403–428. DOI: 10.1037/0033-295X.103.3.403.
A classic paper behind your section on processing speed. Salthouse proposed that slower processing can affect more complex cognition because there may be less time to complete mental operations and earlier information may become less available while later processing occurs. (PubMed)
View the study on PubMed - Park, D. C., & Reuter-Lorenz, P. (2009). The adaptive brain: Aging and neurocognitive scaffolding. Annual Review of Psychology, 60, 173–196. DOI: 10.1146/annurev.psych.59.103006.093656.
Important for the idea that the ageing brain may change how it gets things done. Their Scaffolding Theory of Aging and Cognition proposed that additional neural systems may sometimes be recruited in response to age-related changes. It also reviews evidence for changes in processing speed, working memory, long-term memory, brain structure and white matter. (Annual Reviews)
Read the Annual Review article - Hu et al. (2021). Systematic review and meta-analysis of 36 prospective studies involving 19,040 participants examining white-matter hyperintensities and subsequent cognitive impairment/dementia.
This supports your discussion of white matter, vascular health and cognitive ageing. The important wording for the Research Library is associated with increased risk, rather than treating white-matter changes as a prediction of what will happen to an individual. - Sporadic cerebral small vessel disease and cognitive decline in healthy older adults: A systematic review and meta-analysis (2024).
This analysis included 23 prospective studies and 11,486 participants. Small-vessel disease was associated with small declines in global cognition, executive function, memory and attention. White-matter hyperintensities were associated with decline across all four domains examined. (PubMed Central (PMC))
View the study on PubMed - Nguyen, L., Murphy, K., & Andrews, G. (2019). Cognitive and neural plasticity in old age: A systematic review of evidence from executive functions cognitive training. Ageing Research Reviews, 53, 100912. DOI: 10.1016/j.arr.2019.100912.
One of the strongest references for your statement that the ageing brain remains plastic. Across 20 studies, cognitive training reliably improved trained abilities. Transfer to untrained abilities was more mixed, and evidence for functional brain changes was less consistent. (PubMed)
View the study on PubMed - Nguyen, L., Murphy, K., & Andrews, G. (2019). Immediate and long-term efficacy of executive functions cognitive training in older adults: A systematic review and meta-analysis. Psychological Bulletin, 145(7), 698–733. DOI: 10.1037/bul0000196.
Useful companion evidence when discussing how much cognitive training actually helps and why improvements should not automatically be interpreted as broad improvements in everyday cognition. (PubMed)
View the meta-analysis on PubMed - Park, D. C., Lodi-Smith, J., Drew, L., Haber, S., Hebrank, A., Bischof, G. N., & Aamodt, W. (2014). The impact of sustained engagement on cognitive function in older adults: The Synapse Project. Psychological Science, 25(1), 103–112. DOI: 10.1177/0956797613499592.
Older adults spent about three months learning demanding skills such as digital photography and quilting. The high-challenge conditions produced improvements particularly in episodic memory, supporting the idea that sustained, demanding new learning can still influence cognition in later life. (PubMed Central (PMC))
Read the full Synapse Project paper - Rebok, G. W., Ball, K., Guey, L. T., et al. (2014). Ten-year effects of the Advanced Cognitive Training for Independent and Vital Elderly cognitive training trial on cognition and everyday functioning in older adults. Journal of the American Geriatrics Society, 62(1), 16–24. DOI: 10.1111/jgs.12607.
The ACTIVE trial involved 2,832 adults aged 65+ and provides unusually long follow-up evidence. Training produced domain-specific improvements, with reasoning and processing-speed effects still detectable ten years later. It is particularly valuable because it shows both the possibilities and limits of cognitive training. (PubMed Central (PMC))
Read the ACTIVE 10-year follow-up - Boyke, J., Driemeyer, J., Gaser, C., Büchel, C., & May, A. (2008). Training-induced brain structure changes in the elderly. Journal of Neuroscience, 28(28), 7031–7035. DOI: 10.1523/JNEUROSCI.0742-08.2008.
Older adults learned to juggle and showed transient grey-matter changes in regions associated with the new skill. This is useful supporting evidence that structural plasticity remains possible in older adulthood, while also showing that learning was less proficient than in younger adults. (PubMed) View the study on PubMed
