Testosterone replacement therapy ameliorates spatial cognitive function in age-related hypogonadism (LOH) patients: analysis with a virtual three-dimensional maze

When comparing the behavioral levels of men and women using a maze navigation game created on a PC to investigate spatial cognitive function, many reports indicated that men are significantly faster than women at finding the exit of the maze. Analysis with functional MRI neuroimaging indicates that neural activation at multiple sites were observed during a maze navigation task. Significantly different regions were identified in men and women, with men showing significantly increased activity in the hippocampus. In contrast, women showed increased activity in the Brodmann area of the prefrontal cortex. When differences in the activated regions were taken between men and women, the hippocampal activity showed the largest difference. Since the hippocampal CA1 regions are known to be essentially responsible to spatial navigation ability, the reported difference in spatial ability between men and women could be due to higher testosterone (T) levels in mem than in women, because the application of T can increase hippocampal CA1 neural synapses as observed in rats, for example. In the present study, we developed the original 3D maze navigation test on a PC to accurately analyze spatial cognitive function, and this maze was used to analyze differences in spatial cognitive function between young male and female volunteers. The results showed that males took a distinctly shorter time and path length to escape the maze than females. We applied this maze test to analyze the possible improvement effects of spatial cognitive function by T-replacement therapy (TRT) on male patients with late onset hypogonadism (LOH). LOH patients have significantly low levels of T as well as high Aging males symptoms scale (AMS) scores when compared with healthy men. Upon TRT for 6 weeks, we revealed that the spatial cognitive ability of LOH patients was significantly improved along the increase of T levels and improvement of AMS scores. The observed improvement of spatial cognitive ability of LOH patients could be interpreted as effects of elevation of T levels in the hippocampal CA1 region where androgen receptor (AR) is localized.