What changes in cognitive functioning and the brain are normal?
A decline in cognitive abilities will be experienced by most people as part of the normal ageing process. Typically these changes include memory difficulties and slowed information processing. Some of these changes begin in ones thirties and accelerate after the age fifty.
The cognitive changes result from a number of physical changes in the brain. There is cell loss and shrinkage of cell volume, particulalry in the frontal lobe and hippocampus. Neurotransmitter production (the brain's messengers) may decline due to the loss of cells and receptor cells. There may also be an accumulation of Beta-amyloids, specific proteins, which can interfere with the brain's functioning.
There are normal changes to the brain's blood supply - cerebro-vascular changes - as we age. Vascular change is associated with normal aging, beginning at age 30 years, as the elastin in artery walls is replaced by collagen, a less efficient material.
Structurally the brain undergoes changes which are also age related. Atrophy occurs as the brain shrinks, and the white matter decreases in density. Neurofibrillary tangles are present as part of normal aging, and they are present in the majority of 26 to 32 year old brains.