Genes related to general cognition exert no influence on age-related cognitive decline

Common genetic variants associated with general cognition contribute to better verbal memory and semantic fluency in adults, according to a study. However, they appear to have a null effect on age-related cognitive decline.

Researchers evaluated the rate of change in cognition during a 10-year follow-up period in relation to polygenic predisposition to general cognition. They used data from the English Longitudinal Study of Ageing and looked at a population representative sample of 5,088 adults aged ≥50 years (average age 61.7 years, 44.2 percent men).

In the population, 1,260 participants (24.8 percent) were APOE-ɛ4 carriers. The mean baseline memory score was 11.1, while the mean executive function score was 21.5. During follow-up, the participants exhibited a significant decline in verbal memory (β, −0.13, 95 percent confidence interval [CI], −0.15 to −0.12; p<0.001) and semantic fluency (β, −0.31, 95 percent CI, −0.36 to −0.25; p<0.001). The decline in these cognitive domains was similar in men and women and was pronounced among those aged ≥66 years.

Each one-standard deviation increase in polygenic scores for general cognition (GC-PGS) was associated with an increase of 0.27 points in verbal memory (p<0.001) and of 0.45 points in semantic fluency score (p<0.001). These associations were significant for women and men, as well as in all age groups.

On the other hand, GC-PGS showed no correlation with decreases in verbal memory nor semantic fluency during follow-up.

The findings provide support to previous reports suggesting that the rate of cognitive decline in the general population may be primarily driven by environmental factors.