Anti aging guide

The Aging Brain



How changes of the aging brain could be affecting in human being?

As our years increase, the size of our brain decreases: unpalatable, but true. By the age of 80, the human brain weights about 100 grams (7-8 per cent) less than it did in our 20s. Brain cells, or neurons, are not replaced when they die, and throughout the lifespan we are estimated to lose 50 000 of them a day. That may sound pretty serious, but we do start with some ten billion of them so that a lifetime’s loss is only about 3 per cent of the original total. In any case, the, rate of loss varies between different areas of the cerebral cortex (grey matter), being greatest in the upper part of the temporal lobe and the hindmost part of the frontal lobe. This `neuronal fallout’ is paralleled by a depletion in parts of the cortex of some of the chemical messengers (neurotransmitters) which carry the impulse from one nerve cell to another across the tiny clefts (synapses) which separate them. It has been suggested that it is the number of interconnections between the cells, rather than the number of cells, which is important. It has also been claimed that the number of these connections can be increased in rats by training them in a maze, with the result that the weight of the fore brain and the length and width of the cortex become greater. This appears to be true of rats reared in an intellectually deprived environment, whose brains start off greatly disadvantaged by comparison with those of their siblings which have been intellectually stimulated from birth, and whose brains show no such response to training.

Little granules of a yellowish-brown pigment called lipofuscin accumulate in neuronal cell bodies and this material is thought to represent a waste product. Similarly, starting at around age 60, microscopical examination of the brain will reveal so-called ‘senile plaques’ of degenerated cells and other waste matter scattered throughout the cortex.

These changes to the structure of the brain that accompany the passage of the years are reflected in various physiological measurements, such as the tendency for the frequency of the normal alpha waves of the electroencephalogram (EEG) to become significantly lower. Another example is the flow of blood through the brain which is widely accepted as showing a reduction of about 20 to 25 per cent between ages 30 and 70. However, a cautionary note must be sounded here. The studies on which this information is based are cross-sectional, i.e. they comprise groups of people of different ages all assessed at the same time, and may include numbers of unhealthy individuals who may distort their results. Indeed, it is very difficult to see how a longitudinal study (testing and retesting the same individuals over a long period of time) of the structure of the brain could ever be conducted in human beings.

Posted by Carol Hudgens - April 29, 2012 at 8:21 am