The circalunar cycle of salivary testosterone and the visual-spatial performance

A circalunar cycle is thought to be female sex specific. Results of studies observing the relationship of testosterone and spatial abilities are controversial.

To describe the infradian variations of testosterone and the correlations between salivary testosterone levels and spatial abilities in young healthy volunteers of both sexes.

Testosterone levels in saliva were determined in 53 young adult male and female subjects (mean age--20.89 +/- 0.91 years). The samples of saliva were collected either once (22 subjects) or daily during a period of 30 days (31 subjects). Salivary testosterone was analyzed by RIA. Both groups of subjects were tested on their visual-spatial performance (mental rotation and spatial visualization). All important data about the menstrual cycle of female subjects were also collected. This data and the results of the visual-spatial tests as well as the circalunar cycle in their relationship to the testosterone levels were analyzed.

In this study a circalunar rhythm of testosterone related to the menstrual cycle with a maximum peak in the periovulatory phase was confirmed in women and an analogical circalunar cycle in men was described. A positive correlation of the salivary testosterone levels and the performance in visual-spatial tests in women and a negative dependence in men was found. The outcomes showed a significant statistical difference between the results of the test during the high-testosterone and the low-testosterone phase in both sexes.

The levels of testosterone between the high female and low male range seem to be associated with the best spatial ability performance in adults. A male circalunar rhythm similar to the female one is very likely. Recognizing of the infradian fluctuations in women as in men should have many various clinical implications. (Tab. 2, Fig. 7, Ref. 143.)