Shrinkage, Neuron and Synapse Loss: Aging Takes its Toll on the Brain

Rhonda Witte, BSc

The process of aging is familiar to every individual. Yet, despite this familiarity, it remains one of the greatest biological mysteries. We embark on the aging journey from the very moment we are born and proceed passively until our deaths. It is a concept that some find difficult to comprehend, perhaps because it is seemingly inevitable--beyond one's control.

A multitude of theories has been proposed regarding the aging process. The question "Why do we age?" has sparked interest in many research disciplines. Of particular interest are the neurological aspects of aging. Numerous examinations of the aging brain have been performed, particularly those concerning the neurodegenerative diseases of the elderly. Interestingly, studies using animal models have suggested that estrogen replacement therapy may have a role in both the treatment and prevention of dementia by assisting the regeneration and preservation of neuronal structures.1 Close attention has also been given to the "normal" aging brain and the events that occur over a lifetime.

Along with the heart and striated muscle, the brain is the oldest part of the mammalian body. The neurons of the brain are postmitotic once differentiated and are unable to renew themselves. Thus, the brain is highly susceptible to any cellular damage that may occur with age.