Physical Development in Early Adulthood

Age Range

• Early adulthood: 18-40 years old
• Emerging adulthood: 18-29
• Established adulthood: 30-45ish

Biological Aging

• Multidimensional and multidirectional
• Varies depending on genetics, lifestyle, environment, historical period
• Average life expectancy increased by 25-30 years during the 20th century

Aging at DNA and Body Cells Level

• Programmed effects of specific genes
  • "Biological clock"
  • Aging genes affecting cell repair, immune system, hormone production
  • Telomere shortening
• Cumulative effects of random events
  • "Wear and tear" from spontaneous mutations and cancer
  • Genetic disposition to longevity is indirect
  • Inherits risk and protective factors

Telomeres

• DNA at chromosome ends; safeguard cell stability
• Shorten with each cell duplication; critical length leads to senescence
• Shortening hastened by chronic illness, stress, unhealthy behaviors
• Telomerase
  • Prevents/reverses shortening
  • Positive lifestyle changes enhance telomerase

Aging at Tissues and Organs Level

• Cross-Linkage Theory
  • Protein fibers' cross-links reduce tissue elasticity
  • Declines in organ function, skin, and bodily resilience
• Endocrine System Failure
  • Decrease in growth hormone affects muscle, bone mass, and body fat

Motor Performance

• Peaks in early 20s for speed and strength tasks
• Peaks in late 20s/early 30s for endurance and fine motor tasks
• Sustained training slows decline

Reproductive Capacity

• Ideal in twenties; declines with age
• Women's fertility risks: Sharply increase from 35-44 (fewer/poorer ova)
• Men's fertility risks: Gradual from age 35 (lower sperm volume/motility)

Variations in Health

• US higher death rates in early adulthood compared to other nations
• Health disparities linked to SES
  • Income, education, occupational status
  • Health-related habits and childhood SES

Substance Use and Mental Illness

• Substance use peaks in 19-25-year-olds
• Common substances: tobacco, marijuana, alcohol
• Issues: binge drinking, DUI, prescription/party drugs
• Substance Use Disorder (SUD)
  • 15.4% of adults have SUD
  • High comorbidity with mental illness
• College Drinking
  • Higher binge drinking rates
  • Defined as 4+ drinks for women, 5+ for men in ~2 hours

Tobacco and Marijuana Use

• Cigarette smoking declining; treatments often ineffective
• Prevention and education should target youth

Cognitive Development

• Synapse pruning, neural growth/myelination
• Prefrontal cognitive control network improvement

Cognitive Changes

• Neo-Piagetians: Postformal thought (greater complexity)
• William Perry's Epistemic Cognition
  • Dualistic to relativistic to commitment within relativistic thinking
• Pragmatic Thought (Gisela Labouvie-Vief)
  • Shift from hypothetical to pragmatic thinking
  • Balance of interests, stability, and adaptability

Mature Thinkers

• Integrate logic with emotional awareness
• Make nuanced, balanced decisions
• Recognize and manage conflicting thoughts/emotions