Olfactory functioning and cognitive abilities: a twin study.

A Swedish version of the National Geographic Smell Survey (Wysocki and Gilbert 1989) was completed by 227 twin pairs from the Swedish Adoption/Twin Study of Aging. Twins ranged in age from 45 to 89 years. Quantitative genetic analysis of four measures of olfactory functioning indicated moderate heritability for odor identification and perceived intensity and nonsignificant heritability for odor detection and perceived pleasantness. Bivariate analyses revealed that the relationship between odor identification and measures of verbal ability was primarily genetically mediated. The results provided further support for the hypothesis that odor identification and verbal ability in general tap the same cognitive domain (Larsson 1997).