APP and Alzheimer disease: Interestingly, synaptosomal levels of truncated, but not full-length calpain-1 were increased in APP/PS1 mice of 10 months of age (Fig. 4C), an age when behavioral and pathological symptoms of AD are evident indicating that as the disease progresses there is hyperactivation of both calpain-1 and calpain-2 in the synaptosomes.