Exercise & the Brain: The Complete Evidence Review

Few health claims are repeated as confidently as the idea that exercise prevents dementia. The evidence behind it is real, but more complicated, and more interesting, than the headline suggests. This series works through that evidence in the order it arrived, from the early observational studies through the brain-imaging era, the replication decade, the strength-training trials, and the large prevention studies, keeping the enthusiasm and the corrections in sequence. The honest conclusion is narrower than the promise, and more trustworthy for it. Read it in order, or jump to the question you came for.

The ordered list of all ten parts:

Part 1: Does physical activity lower dementia risk?
Where the belief came from, and the one thing the early studies could never prove.

Part 2: Can exercise studies prove cause?
How researchers tried to design around the biggest weakness in the early evidence.

Part 3: Does exercise grow the hippocampus?
The famous 2011 brain-scan result, and the caution that arrived with it.

Part 4: Did the findings replicate?
What a decade of larger, longer trials actually found when they tried to repeat it.

Part 5: Is strength training good for the brain?
The strongest single signal in the literature, and exactly where it stops.

Part 6: Is the link reverse causation?
The two study designs built to tell cause from coincidence, and the verdict they returned.

Part 7: Does exercise alone prevent decline?
What the randomized trials found, and the one result that worried the field.

Part 8: Do lifestyle programs prevent dementia?
FINGER, POINTER, and what happened when researchers scanned people's brains.

Part 9: How much exercise, and how hard?
What the dose evidence supports, where it plateaus, and where it runs out.

Part 10: So what should you actually do?
The honest summary of what survives the evidence, and what it means for how you live.

This is the first of the five evidence pillars behind Cognitive Resilience. Reviews of sleep, cardiometabolic health, nutrition, and cognitive engagement follow.