Childhood, adolescence, adulthood, and old age: these are the “milestones” of life’s evolution on which crucial stages of brain growth and decline would depend. This is what a recent study in Nature Communications defines.
A “Chameleon” Structure
The brain is made of highly malleable tissue, capable of adapting and changing its behaviors in terms of learning and information gathering, preserving the information it collects, sustaining cognitive and functional abilities, and also losing mental capacities as people move through different ages.
More precisely, with a progressive growth of faculties from 0 to 9 years, reaching full maturity around 30, the stabilization and maintenance of all acquired skills up to roughly 66, and a progressively more pronounced decline with a plateau near 80, edging toward old age. This trajectory unfolds under natural conditions of health and wellness, not influenced by diseases that could alter brain mechanisms and functioning.
This trajectory was defined by a large study evaluating more than 4,000 healthy individuals aged 0 to 90 years. The analyses showed that the structural topology, i.e., the anatomy of brain topography that maps the spatial relationships among body regions, develops in a non-linear fashion across the lifespan and is strongly linked to cognitive trajectories. The researchers’ images, drawn from this substantial data set, referencing 12 specific graph-theoretical metrics, documented the distinctive ways the brain changes over time.
Mapping these data into spaces of varieties, using a uniform-manifold approximation, revealed four major topological turning points in purely brain-based development, aligned with the biological eras already noted, which in turn identify five historic stages of topological development, each marked by distinct topological changes that correspond to age.
These “metamorphoses” concern chiefly the organizing properties that guide the age-topology relationship. The analyses appear to attest to the complex, non-linear nature of human development, with unique phases of topological maturation that can be explained only through a multivariate perspective spanning the entire life and at the population level.
The Changes in Brain Evolution
These topological shifts would correspond to four stages of human biology across the lifespan:
- Infancy: from birth to about 9 years old; during this decade the brain is highly plastic and highly active: neural connections strengthen, and there is a notable increase in both gray matter and white matter, with the acquisition of new skills in language and movement. In this phase the foundations are laid because information will later be processed by specific brain regions that are not yet fully developed or structured at this early life stage. Also in this period the brain forms a large number of synaptic connections, pruning away those that are unnecessary or redundant. There is even speculation that by the end of this phase the brain may begin to show a decline in efficiency after this intensive learning phase. In short, infancy features meaningful correlations in the clustering across 55 of the 90 regions examined.
- Adolescence: around age 9 marks a radical turning point, where the brain begins to reprogram itself to become more efficient. The adolescence phase, according to the researchers’ analysis, lasts more than two decades, averaging until about 30, during which developmental and structural stability would be reached. Yet this period also proves to be the most vulnerable to the emergence of potential mental health issues; alongside this topological and neurobiological shift, there is a advancement in cognitive abilities and changes in socio-emotional and behavioral development. Therefore, the nine-year turning point represents not only a clear change in topological development but also aligns with major cognitive, behavioral, and mental-health milestones.
- Adulthood: spans a long stretch, roughly from 32 to 66 years. The brain in this phase continues to evolve, to change, to adapt, but without radical, substantive turning points, instead showing a steady reorganization. In support of this, the study found 10 topological measures that significantly correlate with age, characterized by a decrease in integration, overall increases in segregation, and modest changes in centrality, where the transition into adulthood is shaped by cultural, historical, and social factors, making it more context-dependent than solely a biological shift. The evidence suggests that during different life stages the white matter integrity and volume rise rapidly, while the macroscopic topological structure becomes more efficient and less segregated. Overall, the results imply that meaningful changes in white matter integrity and topological development occur around the start of the fourth decade of life.
- Old age: can be divided into two phases: an initial period of substantial decline starting around 66, laying the groundwork for age-related diseases such as dementia and hypertension. This vulnerability adds to the natural cognitive decline, including memory loss. Yet the authors emphasize that aging is not solely negative: experience and the wisdom accumulated over years can confer greater emotional regulation and resilience. In the second phase of old age, termed “late aging,” typically around age 80, there would be a rising centrality in which certain brain regions assume greater importance than others. However, while connectivity may diminish, the overall change follows some natural patterns and aligns with expected aging trajectories.
In conclusion, the study reinforces the need for multivariate approaches at the population level and across the lifespan to deepen our understanding of complex topological development, thereby informing prevention strategies and targeted treatments.
Source
Mousley A, Bethlehem RAI, Yeh FG et al. Topological turning points across the human lifespan. Nature Communications, 2025, 16, Article number: 10055. Doi: https://doi.org/10.1038/s41467-025-65974-8
Abbonati a Karla Miller
