Ageing
Figure 5: Process of glycation
It seems, then, that ageing is determined by more than one type of factor. The programmed theory results from primary ageing, which is the degeneration of organs as a result of their uses over time; this is likely to be coded by our genes. And all the theories suggest environmental factors result from secondary ageing. Secondary ageing refers to the changes in the organisms that are a result of a disease process, as well as damages due to life events, such as the experience of head trauma. For example, a neurotransmitter associated with memory, acetylcholine, becomes less abundant with age, and brain receptors of acetylcholine also decline in sensitivity. This proved that the decline in memory is programmed in our life, which could lead to the development of dementia or Alzheimer's disease. This is the primary ageing aspect in the degeneration of memory. However, there are also many other factors which increase the risk of dementia; only about 70 per cent of the risk of Alzheimer's disease is believed to be genetic. Life events such as head injury, smoking, inactivity and obesity which are secondary ageing aspects, may increase the risk of dementia as well. 17
17 Anstey, K, . et al. (1993) ‘ Primary aging, secondary aging, and intelligence ’, Psychol Aging . 8.:562-570. doi:10.1037/0882- 7974.8.4.562; see also Chen, Z. et al. (2022) ‘Role of Cholinergic Signaling in Alzheimer’s Disease.’ Molecules 27.6)1816. doi:10.3390/molecules27061816.
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