Female dominance of both spatial cognitive dysfunction and neuropsychiatric symptoms in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a prevalent neurological disorder affecting memory function in elderly persons. Indeed, AD exhibits abnormality in cognitive behaviors and higher susceptibility to neuropsychiatric symptoms (NPS). Various factors including aging, sex difference and NPS severity, are implicated during in development of AD. In this study, we evaluated behavioral abnormalities of AD model, PDAPP transgenic mice at young age using the Morris Water Maze test, which was established to assess hippocampal-dependent learning and memory. We found that female AD model mice exhibited spatial learning dysfunction and highly susceptible to NPS such as anxiety and depression, whereas spatial reference memory function was comparable in female PDAPP Tg mice to female wild type (WT) mice. Spatial learning function was comparable in male AD model mice to male WT mice. Multiple regression analysis showed that spatial learning dysfunction was associated with NPS severity such as anxiety and depression. Furthermore, the analysis showed that spatial reference memory function was associated with status of depression, but not anxiety. Thus, these results suggest female dominance of spatial learning dysfunction in the AD model mice accompanying increased NPS severity. The understandings of AD model may be useful for the development of therapeutic agents and methods in human AD.