What actually changes in a brain over a lifetime, and which of it is written down in advance.
Why this topic Everyone now has a parent or grandparent whose memory is the family subject nobody raises.
Counted in Europe PMC, where the title or abstract names both this topic and that rsID. The number is papers, not evidence of a cause.
BDNF
Smoking behavior
45 papers →MTHFR
Folate metabolism (MTHFR C677T)
6 papers →APOE
Alzheimer's disease (late onset)
6 papers →HFE
Iron overload risk (hereditary hemochromatosis)
4 papers →HFE
Iron overload risk (HFE H63D)
3 papers →ALDH2
Alcohol flush reaction
3 papers →FTO
Obesity
2 papers →FTO
Obesity
2 papers →GIPR
Obesity
2 papers →MTHFR
Folate metabolism (MTHFR A1298C)
2 papers →ZNF259
Triglyceride levels
2 papers →ADH1B
Alcohol metabolism speed
1 paper →MAPT
Atrial fibrillation
1 paper →APOE
LDL cholesterol
1 paper →APOA5
Triglyceride levels
1 paper →CYP1A2
Caffeine metabolism
1 paper →LGR5
Type 2 diabetes
1 paper →JAZF1
Type 2 diabetes
1 paper →Europe PMC, title and abstract only, searched for “cognitive decline”, “neurodegeneration”, “brain volume”, “white matter” alongside each published rsID. Full text was not counted: it returns every paper with an rsID buried in a supplementary table. Recounted monthly.