Adulthood brings predictable physical changes alongside large individual differences. Understanding typical patterns—especially in movement, sensation, and reproduction—helps psychologists distinguish normal ageing from illness and evaluate how lifestyle and context shape outcomes.

Core pattern: gradual physical change across adulthood

Adult physical development is usually slow and cumulative, not abrupt. Change reflects both normal biological ageing and differences in health, environment, and behaviour.

Primary vs secondary ageing

Primary ageing describes normative, species-typical biological change; secondary ageing reflects disease, injury, and lifestyle effects that are more preventable.

A key implication is that some decline is typical, but the rate and impact of change vary widely due to secondary ageing factors (e.g., smoking, inactivity, chronic stress).

Mobility and physical performance

Across adulthood, many people experience reduced mobility and slower physical performance, often due to changes in muscle, joints, and balance.

Strength, flexibility, and balance

Common trends include:

• Reduced muscle mass and strength (especially without resistance activity)

• Stiffer joints and decreased flexibility

• Slower reaction time and reduced rapid coordination

• Balance challenges, increasing fall risk, especially in later adulthood

Why mobility often declines

Contributors frequently include:

• Sarcopenia (age-related muscle loss)

• Degenerative joint changes (e.g., osteoarthritis)

• Lower cardiovascular capacity with inactivity

• Medication side effects and comorbid conditions that compound weakness or dizziness

Mobility changes matter psychologically because they can alter independence, access to rewarding activities, and perceived control, even when cognitive ability is unchanged.

This flow diagram summarizes sarcopenia as a self-reinforcing process: biological and lifestyle factors reduce muscle mass/strength, which lowers mobility and activity, further accelerating decline. It supports the psychological point that reduced mobility can constrain independence and daily functioning through cascading effects. Source

Sensory abilities

The syllabus emphasises gradual declines in sensory abilities. These changes typically accumulate over decades and can affect safety, communication, and quality of life.

Vision changes

Typical age-related patterns:

• Presbyopia: reduced near focusing ability, often noticeable in midlife

• Greater need for brighter light and slower adaptation to darkness

• Increased sensitivity to glare and reduced contrast sensitivity

This diagram illustrates ocular accommodation: the ciliary muscle changes tension on the lens to alter its curvature for near versus distant focus. Presbyopia is largely explained by reduced ability of the lens/ciliary system to produce the near-focus shape, making close objects harder to see clearly. Source

Visual decline can indirectly affect social functioning (e.g., reduced driving confidence, fewer evening activities) and may be misinterpreted as disinterest rather than a sensory limitation.

Hearing changes

Hearing commonly shows:

• Presbycusis: gradual loss, often first for high-frequency sounds

• Greater difficulty understanding speech in noisy environments

• Increased listening effort, which can lead to fatigue during conversations

These sensory changes can influence social connection when people withdraw from challenging environments, even when motivation for relationships remains strong.

Reproductive function and menopause

Reproductive ageing is a major physical change in adulthood, most clearly marked by menopause in females, with a more gradual decline in male reproductive functioning.

Female reproductive ageing and menopause

Menopause involves the end of ovulation and menstruation and reduced ovarian hormone production.

This figure plots typical estrogen patterns across adulthood, highlighting the steep decline associated with the menopause transition. It helps connect hormonal change to downstream effects discussed in the notes (e.g., fertility changes and symptom variability). Source

Common associated changes (varying widely by individual) include:

• Hot flashes and night sweats

• Sleep disruption and vaginal dryness

• Changes in body composition and bone density risk over time (partly hormone-related)

Psychological outcomes are shaped by context: symptom severity, cultural expectations, health access, and stress levels can all influence how menopause is experienced.

Male reproductive ageing

Male fertility and sexual functioning often show gradual rather than stage-like change:

• Slower testosterone decline on average (with high individual variability)

• Increased time to achieve erection and longer refractory periods

• Greater impact of cardiovascular health and medication effects on sexual functioning

Individual differences and modifiers

Although declines are common, they are not uniform. Important modifiers include:

• Physical activity (a major protective factor for strength, balance, and functional ability)

• Chronic disease burden (e.g., diabetes, cardiovascular conditions)

• Nutrition, sleep quality, and substance use

• Access to preventive healthcare and safe environments for movement