Genetic markers associated with high versus low performance on episodic memory tasks.

Associations were studied between six serum protein polymorphisms (C3, BF, HP, ORM, TF, and GC) and high versus low scoring on episodic memory tasks in an attempt to identify QTL (quantitative trait loci) contributing to the heritability of this quantitative trait. Since a highly significant sex difference (p = .00002) was found with respect to the distribution of high and low scoring, with men showing a poorer performance, associations were studied separately for males and females. In females significant differences (p < .05) between the high and the low groups were found in four of six marker systems (C3, HP, TF, and CG), whereas in males a significant difference was found only in the HP system. Significant differences from population frequencies were also found more frequently in females than in males. The strongest marker associations were found with complement C3 and the acute-phase reactant HP, which suggests that immune response factors may be of importance in preserving episodic memory function. The overall results appear to indicate that episodic memory is a multifactorial and heritable quantitative trait where sex is an important determinant.