A curvilinear relationship between testosterone and spatial cognition in humans: possible influence of hand preference.

The nature of the relationship, if any, between performance on visuo-spatial tests in humans and circulating testosterone (T) concentrations remains controversial. We investigated possible relationships between salivary T and cortisol (C) concentrations and performance on visuo-spatial and verbal cognitive tests in a sample of healthy young adults. Among right-handers, salivary T was found to be negatively correlated with spatial performance in males, but was positively correlated with a measure of spatial visualization in females. This pattern was not evident in left-handers. Across the entire observed range of T, the relationship between spatial cognition and T was best described by an inverted quadratic function in right-handers, but not in left-handers. A significant difference in spatial accuracy was seen among right-handers tested in early vs. late morning testing sessions, in accordance with the expected diurnal change in circulating T. No significant relationships between salivary C and visuo-spatial performance were found. These results are consistent with prior literature suggesting a curvilinear relationship between spatial performance and circulating T concentrations, with intermediate levels of T being associated with better spatial functioning, but raise the possibility that hand preference may be one factor that moderates the observed relationship.