1) Ageing: It is due to natural changes and the result of disease. Also known as Primary ageing, it refers to the changes in human functional capacity due to changes in cells and tissues, causing deterioration of the biological system and its subsystems and susceptibility to disease and mortality. It is the preprogrammed coding that our bodies follow and the gradual and inevitable process of body deterioration that takes place throughout life.
2) Psychological Ageing: It refers to continuous growth and change in cognition and personality. This change in cognition affects person’s ability to process the information and their susceptibility to persuasion.
3) Social Ageing: It refers to changes in social relationships that define social status within a society, power relationships within social groups and various roles people are expected to play at various stages of life.
4) Secondary Ageing: It results from negative environmental influences, poor diet and disease, lack of physical activity, poor nutrition, environmental pollution, stress and unhealthy activities like smoking and drinking, and exposure to hazardous materials.