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Theories of ageing - Coggle Diagram

- - - - An internal biological clock regulates development, growth, maturity and ageing by sequentially switching genes on and off
        
        E.g. Hayflick limit: Fibroblasts grown in culture stop dividing after about 50 cell divisions and undergo replicative senescence (normal somatic cells reach an irreversible stage of cell cycle arrest following multiple rounds of replication). Fibroblasts from older individuals stop dividing after fewer divisions than those from younger – the lifespan of a species correlated with the replication limit.
    - - “Wear and tear” – accumulation of damage/strain throughout life --> damaged molecules and less functional cells and organs (critique: overlooks ability to repair damage)
      - The rate of living theory - energy expenditure is inversely proportional to lifespan. The faster the metabolism, the shorter the lifespan.
      - Free radical-theory – reactive oxygen species occur as a by-product of normal metabolism and from external sources --> damage to lipids, DNA, proteins and tissue.
    - - Mutation accumulation: Ageing occurs as a result of accumulation of somatic cellular damage. Genes causing disease early in life will be eliminated thanks to selection, as the individual does not live long enough to reproduce. Genes causing late-life disease will ‘survive’.
      - Trade off: some genes have more than one effect. Some effects might benefit early survival but cause harm in later life.
      - Disposable soma theory: organisms balance the need for repair and maintenance of somatic cells with the resources needed for reproduction. Organisms must preferably direct resources to support early survival and reproduction at the expense of repairing somatic cells.
  - - - Stage theories – human development and learning are lifelong processes:
        Erik Erikson’s 8 stages. Stage 8 addresses post-retirement age ‘seek to balance life successes and disappointments and to reach a compassionate, philosophical comprehension of the whole’.
      - Age and cognition:
        Older people perform more poorly in tasks requiring fluid intelligence (to reason abstractly, to solve problems in new situations)
        Older people perform equally well or better in tasks requiring crystallized intelligence (acquired knowledge and skills eg vocabulary, social judgment)
      - The positivity effect:
        A tendency to prefer positive over negative information with regard to attention and memory processes
        Note: Sadness, depression, frustration are not normal signs of ageing
      - Emotional self-regulation -
        Socioemotional selectivity theory:
        The reduced network size and rate of social interaction observed among older adults are a part of a life-long process intending to maximise the social and affective goods achieved from social interaction, and to reduce any socially or emotionally based risks.
        Older adults are making an active selection about who they want to interact with socially, and are not only forced to exclude certain of their relations due to e.g. own ill health or closeness to death
      - Behavioural regulation (the model of selective optimisation with compensation):
        Selection: focus on the choice and prioritisation of important goals to pursue, either based on personal preferences or due to resource losses
        Optimisation: individuals invest additional resources to achieve their goals.
        Compensation: replacing means that do not contribute to goal attainment with more effective means.