Some people have a gene variant that affects how their brain's wiring develops over time — those with the common version (C) show normal brain changes as they age, while those with two copies of the less common version (T) don't show as much change.

What we've found so far is that the evidence leans toward the idea that the FADS rs174583 gene has less influence on brain white matter in adults over 60. Our analysis of the available research shows this pattern across two separate lines of evidence. We looked at 122 total supporting assertions and found no studies that refute this idea. The first line of evidence suggests that people with the common C version of the FADS rs174583 gene show typical age-related changes in brain white matter, while those with two copies of the less common T version show less change over time [1]. This implies that the gene plays a role in how brain wiring evolves with age, but the effect appears to be more pronounced in earlier life. The second line of evidence supports the idea that genetic influences on brain structure may weaken with age [2]. Specifically, the impact of this gene on white matter seems to diminish after age 60. In other words, while genes like FADS rs174583 might shape brain development earlier in life, their role becomes less noticeable in older adults. Our current analysis shows that both lines of evidence point in the same direction — the gene’s effect on white matter appears to fade later in life. However, we base this on the data we’ve reviewed so far, and future evidence could refine or change this understanding. Practical takeaway: Genes may guide brain changes when we’re younger, but after 60, other factors might matter more for brain health than this particular gene.