APP and Alzheimer disease: The 6–7-mo and 9–10-mo APP/PS1 mice showed a gradual accumulation of Aβ depositions within the OB and an aggravated AD pathology, and these effects were accompanied by gradual decrease in the synaptic protein levels and dendritic spine density of GCs, which suggested a decreased number of inhibitory synapses and a weaker inhibitory effect of GCs on MCs in the presence of excessive Aβ depositions.