DLG4 and Cognitive impairment: For example, in the 5XFAD mouse, increases in intraneuronal Aβ and Aβ plaques occur at 1.5-2 months of age, whereas the loss of the post-synaptic marker, PSD95, is not evident until animals are 9 months old, and is preceded by the cognitive deficits that occur in 4-5 month old animals [36].