In this Chapter...

• Aging in different ways

• What we know and don’t know about aging

Aging in Different Ways

• Severe declines in memory, intelligence, verbal fluency, etc. are not a part of normal aging

• Effects of age on brain function are very subtle and selective

  • Once most people reach their 70s, they may find themselves forgetting names, phone numbers, etc.

  • The response to conflicting information slows down as well

• Dementia: a progressive and severe impairment in mental function that interferes with activities of daily living

  • Types of dementia:

    • Alzheimer’s disease- the most common

    • Cerebrovascular disease

    • Pick’s disease

    • Lewy body disease

What we know and don’t know about aging

• The brain reaches its maximum weight near the age of 20

• Subtle changes in the chemistry and structure of the brain begin in midlife for most people

• The brain is at risk of losing some neurons but not widespread neuron loss

  • This distinguishes normal aging from neurodegenerative disease

• After the damage or loss of neurons, the remaining healthy ones are able to expand dendrites and fine-tune connections with other neurons

  • If the cell body is intact, the damaged neuron can induce changes in its axon and dendrites to regrow them

• The brain cannot generate new neurons

  • Not many stem cells exist in the brain

  • The stem cell number in the brain actually decreases as a person ages

Changes in Intellectual Capacity

• As people age, the speed of carrying out tasks is slower but their vocabulary improves

  • There is an increase in the type of intelligence relying on learned or stored information but a decrease in the type that depends on the ability to deal with new information

• The brain is only as resilient as its circuitry

  • When the circuitry breaks down, neurons adapt by expanding their roles

    • Larger portions of the brain are “recruited” so older people can reach performance levels similar to younger adults

• Motor learning generates new synapses

  • This is how aerobic exercise improves cognitive performance

• Many theories for normal brain aging:

  • Specific “aging genes” turned on

  • Accumulation of mutations/other types of DNA damage

  • Hormonal influences

  • The immune system has gone awry

  • Accumulation of oxidative damage caused by free radicals

    • Free radicals: cell byproducts that destroy fats and proteins vital to cellular functions

• Physical and mental exercise are both effective means of slowing the effects of brain aging