CONCISE THEORIES OF AGING

Theories of Aging

 1.  Programmed Theory of Aging

 2.  Running out of Program Theory

3.  Mutation Theory of Aging

 4.  Autoimmune Theory of Aging

5.  Cross-linking Theory

 6.  Free-Radical Theory

 7.  Cycling/Non-Cycling Cell Theory

 8.  Error Catastrophe Theory

9.  DNA Repair Mechanisms

 10.  Other Theories

1.   Programmed Theory & Running Out of Program Theory

 Programmed Theory: In this theory, there is a genetic sequence activated at a particular time that regulates death.   

2. Running Out Program: All events are specifically programmed into genome and are sequentially activated.  After maturation genes have been activated there are no more programs to be played and as cells age there may be chance of inactivation of genes that cannot be turned on

3.  Mutation Theory: Random mutation hits genes and changes in proteins occur (viruses may be involved)

4.  Autoimmune Theory: As one gets older there is a greater incidence of autoimmune disease.  Regulation of self-recognition is breaking down

5.  Cross-Linking Theory: In DNA and proteins, cross linking prevents the molecules from functioning properly

6.  Free-Radical Theory: Free radicals are  highly reactive molecules that are formed during most chemical reactions.  Cells can normally get rid of these but as a cell ages its ability to get rid of FR decreases (oxidative stress)  

7. Cycling/Non-Cycling Theory: Applies to tissues able to proliferate.  Relates to whether a growing cell is blocked at a certain stage of proliferation and cannot continue to grow (i.e..., bone marrow cells)

8. Error Catastrophe: Postulates that nothing is perfect.  There is a chance for a mistake to occur.  The more occurrences that happen, the greater is the chance that a mistake will happen.  i.e..., live long enough, enough mistakes happen, death occurs

9. DNA Repair Mechanisms:  DNA constantly needs repairs (mutations, radiation, chemicals, polymerase, etc...).  Repair mechanisms decrease with age