Week 2

Theories of Ageing

• Non-stochastic (Programmed) factors indicate that ageing follows a biological timetable regulated by genetics.
• Stochastic (Damage-related) factors suggest that ageing results from accumulated cellular damage due to metabolic by-products.
• Metabolic theories propose that a faster metabolism correlates with a shorter lifespan, influenced by energy limits and hormonal adaptations.
• Cellular theories include concepts such as the Hayflick limit, where cells can only divide a finite number of times; telomeres shorten with each division leading to instability in chromosomes.
• Genetic programming theories suggest that ageing processes are coded into our genetics, resulting in pre-programmed cell death through apoptosis.

Genetics and Ageing

• Genetic mutations can significantly impact longevity; a single mutation in worms can nearly double lifespan.
• Heritability of longevity is notable, especially in offspring of long-lived individuals who tend to be less prone to age-related diseases.
• Certain rare genetic disorders (e.g., Werner’s syndrome, Cockayne syndrome) can cause accelerated ageing, functioning at eight times the normal rate.

Definitions of Ageing

• Ageing involves an exponential increase in mortality, physiological functional decline, and heightened vulnerability to diseases.
• Life expectancy refers to average lifespan expectancy, while longevity represents life duration under ideal conditions. Lifespan denotes the typical duration for life events.

Physical Changes with Age

• Appearance changes include alterations in skin, hair, voice, body build, and overall mobility.
• Sensory system changes affect vision, hearing, balance, taste, and smell, impacting daily activities and quality of life.

Vital Systems

• Ageing influences vital functions across various systems:
  • Cardiovascular health declines.
  • Respiratory diseases become more prevalent.
  • The reproductive system undergoes notable changes.
  • The autonomic nervous system is affected by age-related alterations.

Brain Changes with Age

• Neuronal decline occurs, including reduced number and size of dendrites, formation of tangles in axon fibers, and increased protein deposits.
• White matter hyperintensities (WMH) are lesions that increase with age, linked to dementia and strokes.
• Neurotransmitter levels decrease, particularly dopamine, serotonin, and acetylcholine, leading to cognitive and emotional changes.
• Brain structure shrinks notably in regions such as the prefrontal cortex and hippocampus, impacting memory and executive function.

Impacts of Brain Changes

• Ageing impairs executive functioning and memory due to structural brain changes.
• Emotional processing improves with age, leading to better emotional regulation.
• The Parieto-Frontal Integration Theory (P-FIT) posits that intelligence arises from an interconnected network in the brain's parietal and frontal areas.

Theories Explaining Age-related Brain Changes

• CRUNCH (compensation-related utilization of neural circuits hypothesis) suggests older adults use additional brain networks to maintain cognitive functions.
• STAC-r (scaffolding theory of cognitive age revised) proposes that older adults develop strategies to compensate for cognitive decline through enhanced neural flexibility.

Summary of Learning Outcomes

• Three theories of ageing encompass programmed, stochastic, and metabolic perspectives.
• Key aspects of primary ageing include changes in appearance, sensory systems, and vital functions.
• Psychological implications of ageing offer insights into cognition, emotion, and social interactions.
• Primary ageing of the brain involves understanding neuronal changes, neurotransmitter decline, and structural impacts on cognitive abilities.

Explore the key theories of ageing as discussed in Week 2 of the 3012PS course. This quiz covers the primary ageing factors impacting both the body and brain, including appearance, mobility, sensory changes, and vital systems. Engage in the psychological implications of these ageing processes.