During normal aging the brain undergoes many changes resulting in a gradual but detectable cognitive decline that is associated with limited neuronal loss, glial proliferation in the cortex, and gross weight decrease of 2–3% per decade [1], [2]. On the molecular level, the mechanisms driving aging of the brain are not yet understood, but likely include mitochondrial DNA damage [3] and chronic oxidative stress [4]. This slow decline in cognitive ability does not interfere with normal function through at least 100 years of life. In contrast, Alzheimer's disease (AD) is a debilitating neurodegenerative disorder associated with a rapid cognitive decline with an average survival of 5–10 years after the diagnosis [5], [6], [7]. Age is the main AD risk factor with almost half of the population over age 85 affected. AD, however, clearly differs from the normal aging in that it causes dramatic loss of synapses, neurons and brain activity in specific anatomical regions, and results in massive atrophy and gliosis [1], [8].
