How the brain’s clock speeds up around middle age can determine future health and dementia

Our brains change more rapidly at various times of our lives, as though life’s clock was ticking faster than usual. Childhood, adolescence and very old age are good examples of this. Yet for much of adulthood, the same clock seems to tick fairly regularly. One lap around the Sun; one year older.

However, there may be a stage of life when the brain’s clock starts speeding up. The brain starts changing without you necessarily noticing it. It may even be caused (partly) by what’s in your blood. This stage of brain ageing during your 40s to 50s, or “middle-ageing”, may predict your future health.

Psychologists studying how our mental faculties change with age find that they decline gradually, starting in our 20s and 30s. However, when assessing people’s memory of everyday events, the change over time appears to be especially rapid and unstable during middle age. That is, even among healthy people, some experience rapidly deteriorating memory, while for others, it may even improve.

This suggests that the brain may be going through accelerating, as opposed to gradual, change during this period. Several structures of the brain have been found to change in midlife. The hippocampus, an area critical for forming new memories, is one of them.

It shrinks throughout much of adulthood, and this...

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